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14900 lines
375 KiB
HTML
<HTML><HEAD>
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<TITLE>BASH(1) Manual Page</TITLE>
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</HEAD>
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<BODY><TABLE WIDTH=100%>
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<TR>
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<TH ALIGN=LEFT width=33%>BASH(1)<TH ALIGN=CENTER width=33%>2022 September 19<TH ALIGN=RIGHT width=33%>BASH(1)
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</TR>
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</TABLE>
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<BR><A HREF="#index">Index</A>
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<HR>
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<A NAME="lbAB"> </A>
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<H3>NAME</H3>
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bash - GNU Bourne-Again SHell
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<A NAME="lbAC"> </A>
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<H3>SYNOPSIS</H3>
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<B>bash</B>
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[options]
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[command_string | file]
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<A NAME="lbAD"> </A>
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<H3>COPYRIGHT</H3>
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Bash is Copyright © 1989-2022 by the Free Software Foundation, Inc.
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<A NAME="lbAE"> </A>
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<H3>DESCRIPTION</H3>
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<B>Bash</B>
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is an <B>sh</B>-compatible command language interpreter that
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executes commands read from the standard input or from a file.
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<B>Bash</B>
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also incorporates useful features from the <I>Korn</I> and <I>C</I>
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shells (<B>ksh</B> and <B>csh</B>).
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<P>
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<B>Bash</B>
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is intended to be a conformant implementation of the
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Shell and Utilities portion of the IEEE POSIX specification
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(IEEE Standard 1003.1).
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<B>Bash</B>
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can be configured to be POSIX-conformant by default.
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<A NAME="lbAF"> </A>
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<H3>OPTIONS</H3>
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All of the single-character shell options documented in the
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description of the <B>set</B> builtin command, including <B>-o</B>,
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can be used as options when the shell is invoked.
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In addition, <B>bash</B>
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interprets the following options when it is invoked:
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<P>
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<DL COMPACT>
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<DT><B>-c</B>
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<DD>
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If the
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<B>-c</B>
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option is present, then commands are read from the first non-option argument
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<I>command_string</I>.
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If there are arguments after the
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<I>command_string</I>,
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the first argument is assigned to
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<B>$0</B>
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and any remaining arguments are assigned to the positional parameters.
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The assignment to
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<B>$0</B>
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sets the name of the shell, which is used in warning and error messages.
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<DT><B>-i</B>
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<DD>
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If the
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<B>-i</B>
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option is present, the shell is
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<I>interactive</I>.
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<DT><B>-l</B>
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<DD>
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Make
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<B>bash</B>
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act as if it had been invoked as a login shell (see
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<FONT SIZE=-1><B>INVOCATION</B>
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</FONT>
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below).
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<DT><B>-r</B>
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<DD>
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If the
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<B>-r</B>
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option is present, the shell becomes
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<I>restricted</I>
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(see
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<FONT SIZE=-1><B>RESTRICTED SHELL</B>
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</FONT>
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below).
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<DT><B>-s</B>
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<DD>
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If the
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<B>-s</B>
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option is present, or if no arguments remain after option
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processing, then commands are read from the standard input.
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This option allows the positional parameters to be set
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when invoking an interactive shell or when reading input
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through a pipe.
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<DT><B>-D</B>
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<DD>
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A list of all double-quoted strings preceded by <B>$</B>
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is printed on the standard output.
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These are the strings that
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are subject to language translation when the current locale
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is not <B>C</B> or <B>POSIX</B>.
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This implies the <B>-n</B> option; no commands will be executed.
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<DT><B>[-+]O [</B><I>shopt_option</I>]
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<DD>
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<I>shopt_option</I> is one of the shell options accepted by the
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<B>shopt</B> builtin (see
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<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
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</FONT>
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below).
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If <I>shopt_option</I> is present, <B>-O</B> sets the value of that option;
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<B>+O</B> unsets it.
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If <I>shopt_option</I> is not supplied, the names and values of the shell
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options accepted by <B>shopt</B> are printed on the standard output.
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If the invocation option is <B>+O</B>, the output is displayed in a format
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that may be reused as input.
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<DT><B>--</B>
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<DD>
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A
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<B>--</B>
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signals the end of options and disables further option processing.
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Any arguments after the
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<B>--</B>
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are treated as filenames and arguments. An argument of
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<B>-</B>
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is equivalent to <B>--</B>.
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</DL>
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<P>
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<B>Bash</B>
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also interprets a number of multi-character options.
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These options must appear on the command line before the
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single-character options to be recognized.
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<P>
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<DL COMPACT>
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<DT><B>--debugger</B>
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<DD>
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Arrange for the debugger profile to be executed before the shell
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starts.
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Turns on extended debugging mode (see the description of the
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<B>extdebug</B>
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option to the
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<B>shopt</B>
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builtin below).
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<DT><B>--dump-po-strings</B>
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<DD>
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Equivalent to <B>-D</B>, but the output is in the GNU <I>gettext</I>
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<B>po</B> (portable object) file format.
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<DT><B>--dump-strings</B>
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<DD>
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Equivalent to <B>-D</B>.
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<DT><B>--help</B>
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<DD>
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Display a usage message on standard output and exit successfully.
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<DT><B>--init-file</B> <I>file</I><DD>
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<DT><B>--rcfile</B> <I>file</I><DD>
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Execute commands from
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<I>file</I>
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instead of the standard personal initialization file
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<A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>
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if the shell is interactive (see
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<FONT SIZE=-1><B>INVOCATION</B>
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</FONT>
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below).
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<DT><B>--login</B>
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<DD>
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Equivalent to <B>-l</B>.
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<DT><B>--noediting</B>
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<DD>
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Do not use the GNU
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<B>readline</B>
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library to read command lines when the shell is interactive.
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<DT><B>--noprofile</B>
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<DD>
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Do not read either the system-wide startup file
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<A HREF="file:/etc/profile"><I>/etc/profile</I></A>
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or any of the personal initialization files
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<A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A>,
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<A HREF="file:~/.bash_login"><I>~/.bash_login</I></A>,
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or
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<A HREF="file:~/.profile"><I>~/.profile</I></A>.
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By default,
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<B>bash</B>
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reads these files when it is invoked as a login shell (see
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<FONT SIZE=-1><B>INVOCATION</B>
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</FONT>
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below).
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<DT><B>--norc</B>
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<DD>
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Do not read and execute the personal initialization file
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<A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>
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if the shell is interactive.
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This option is on by default if the shell is invoked as
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<B>sh</B>.
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<DT><B>--posix</B>
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<DD>
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Change the behavior of <B>bash</B> where the default operation differs
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from the POSIX standard to match the standard (<I>posix mode</I>).
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See
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<FONT SIZE=-1><B>SEE ALSO</B>
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</FONT>
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below for a reference to a document that details how posix mode affects
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bash's behavior.
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<DT><B>--restricted</B>
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<DD>
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The shell becomes restricted (see
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<FONT SIZE=-1><B>RESTRICTED SHELL</B>
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</FONT>
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below).
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<DT><B>--verbose</B>
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<DD>
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Equivalent to <B>-v</B>.
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<DT><B>--version</B>
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<DD>
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Show version information for this instance of
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<B>bash</B>
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on the standard output and exit successfully.
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</DL>
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<A NAME="lbAG"> </A>
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<H3>ARGUMENTS</H3>
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If arguments remain after option processing, and neither the
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<B>-c</B>
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nor the
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<B>-s</B>
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option has been supplied, the first argument is assumed to
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be the name of a file containing shell commands.
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If
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<B>bash</B>
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is invoked in this fashion,
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<B>$0</B>
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is set to the name of the file, and the positional parameters
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are set to the remaining arguments.
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<B>Bash</B>
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reads and executes commands from this file, then exits.
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<B>Bash</B>'s exit status is the exit status of the last command
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executed in the script.
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If no commands are executed, the exit status is 0.
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An attempt is first made to open the file in the current directory, and,
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if no file is found, then the shell searches the directories in
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<FONT SIZE=-1><B>PATH</B>
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</FONT>
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for the script.
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<A NAME="lbAH"> </A>
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<H3>INVOCATION</H3>
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A <I>login shell</I> is one whose first character of argument zero is a
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<B>-</B>,
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or one started with the
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<B>--login</B>
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option.
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<P>
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An <I>interactive</I> shell is one started without non-option arguments
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(unless <B>-s</B> is specified)
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and without the
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<B>-c</B>
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option,
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whose standard input and error are
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both connected to terminals (as determined by
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<I>isatty</I>(3)),
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or one started with the
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<B>-i</B>
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option.
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<FONT SIZE=-1><B>PS1</B>
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</FONT>
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is set and
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<B>$-</B>
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includes
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<B>i</B>
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if
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<B>bash</B>
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is interactive,
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allowing a shell script or a startup file to test this state.
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<P>
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The following paragraphs describe how
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<B>bash</B>
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executes its startup files.
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If any of the files exist but cannot be read,
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<B>bash</B>
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reports an error.
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Tildes are expanded in filenames as described below under
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<B>Tilde Expansion</B>
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in the
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<FONT SIZE=-1><B>EXPANSION</B>
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</FONT>
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section.
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<P>
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When
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<B>bash</B>
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is invoked as an interactive login shell, or as a non-interactive shell
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with the <B>--login</B> option, it first reads and
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executes commands from the file <A HREF="file:/etc/profile"><I>/etc/profile</I></A>, if that
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file exists.
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After reading that file, it looks for <A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A>,
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<A HREF="file:~/.bash_login"><I>~/.bash_login</I></A>, and <A HREF="file:~/.profile"><I>~/.profile</I></A>, in that order, and reads
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and executes commands from the first one that exists and is readable.
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The
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<B>--noprofile</B>
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option may be used when the shell is started to inhibit this behavior.
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<P>
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When an interactive login shell exits,
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or a non-interactive login shell executes the <B>exit</B> builtin command,
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<B>bash</B>
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reads and executes commands from the file <A HREF="file:~/.bash_logout"><I>~/.bash_logout</I></A>, if it
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exists.
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<P>
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When an interactive shell that is not a login shell is started,
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<B>bash</B>
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reads and executes commands from <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>, if that file exists.
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This may be inhibited by using the
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<B>--norc</B>
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option.
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The <B>--rcfile</B> <I>file</I> option will force
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<B>bash</B>
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to read and execute commands from <I>file</I> instead of <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>.
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<P>
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When
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<B>bash</B>
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is started non-interactively, to run a shell script, for example, it
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looks for the variable
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<FONT SIZE=-1><B>BASH_ENV</B>
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</FONT>
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in the environment, expands its value if it appears there, and uses the
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expanded value as the name of a file to read and execute.
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<B>Bash</B>
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behaves as if the following command were executed:
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<P>
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<DL COMPACT><DT><DD>
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<TT>if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi</TT>
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</DL>
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<P>
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but the value of the
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<FONT SIZE=-1><B>PATH</B>
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</FONT>
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variable is not used to search for the filename.
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<P>
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If
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<B>bash</B>
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is invoked with the name
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<B>sh</B>,
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it tries to mimic the startup behavior of historical versions of
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<B>sh</B>
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as closely as possible,
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while conforming to the POSIX standard as well.
|
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When invoked as an interactive login shell, or a non-interactive
|
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shell with the <B>--login</B> option, it first attempts to
|
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read and execute commands from
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<A HREF="file:/etc/profile"><I>/etc/profile</I></A>
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and
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<A HREF="file:~/.profile"><I>~/.profile</I></A>,
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in that order.
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The
|
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<B>--noprofile</B>
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option may be used to inhibit this behavior.
|
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When invoked as an interactive shell with the name
|
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<B>sh</B>,
|
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<B>bash</B>
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looks for the variable
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<FONT SIZE=-1><B>ENV</B>,
|
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</FONT>
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expands its value if it is defined, and uses the
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expanded value as the name of a file to read and execute.
|
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Since a shell invoked as
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<B>sh</B>
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does not attempt to read and execute commands from any other startup
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files, the
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<B>--rcfile</B>
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option has no effect.
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A non-interactive shell invoked with the name
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<B>sh</B>
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does not attempt to read any other startup files.
|
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When invoked as
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<B>sh</B>,
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<B>bash</B>
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enters
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<I>posix</I>
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mode after the startup files are read.
|
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<P>
|
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|
When
|
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<B>bash</B>
|
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is started in
|
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<I>posix</I>
|
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mode, as with the
|
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<B>--posix</B>
|
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|
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command line option, it follows the POSIX standard for startup files.
|
|
In this mode, interactive shells expand the
|
|
<FONT SIZE=-1><B>ENV</B>
|
|
|
|
</FONT>
|
|
variable and commands are read and executed from the file
|
|
whose name is the expanded value.
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No other startup files are read.
|
|
<P>
|
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|
|
<B>Bash</B>
|
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|
attempts to determine when it is being run with its standard input
|
|
connected to a network connection, as when executed by
|
|
the historical remote shell daemon, usually <I>rshd</I>,
|
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or the secure shell daemon <I>sshd</I>.
|
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If
|
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<B>bash</B>
|
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|
determines it is being run non-interactively in this fashion,
|
|
it reads and executes commands from <A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>,
|
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if that file exists and is readable.
|
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It will not do this if invoked as <B>sh</B>.
|
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The
|
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<B>--norc</B>
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option may be used to inhibit this behavior, and the
|
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<B>--rcfile</B>
|
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|
|
option may be used to force another file to be read, but neither
|
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<I>rshd</I> nor <I>sshd</I> generally invoke the shell with those options
|
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or allow them to be specified.
|
|
<P>
|
|
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If the shell is started with the effective user (group) id not equal to the
|
|
real user (group) id, and the <B>-p</B> option is not supplied, no startup
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files are read, shell functions are not inherited from the environment, the
|
|
<FONT SIZE=-1><B>SHELLOPTS</B>,
|
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|
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</FONT>
|
|
<FONT SIZE=-1><B>BASHOPTS</B>,
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|
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</FONT>
|
|
<FONT SIZE=-1><B>CDPATH</B>,
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
variables, if they appear in the environment, are ignored,
|
|
and the effective user id is set to the real user id.
|
|
If the <B>-p</B> option is supplied at invocation, the startup behavior is
|
|
the same, but the effective user id is not reset.
|
|
<A NAME="lbAI"> </A>
|
|
<H3>DEFINITIONS</H3>
|
|
|
|
The following definitions are used throughout the rest of this
|
|
document.
|
|
|
|
<DL COMPACT>
|
|
<DT><B>blank</B>
|
|
|
|
<DD>
|
|
A space or tab.
|
|
<DT><B>word</B>
|
|
|
|
<DD>
|
|
A sequence of characters considered as a single unit by the shell.
|
|
Also known as a
|
|
<B>token</B>.
|
|
|
|
<DT><B>name</B>
|
|
|
|
<DD>
|
|
A
|
|
<I>word</I>
|
|
|
|
consisting only of alphanumeric characters and underscores, and
|
|
beginning with an alphabetic character or an underscore. Also
|
|
referred to as an
|
|
<B>identifier</B>.
|
|
|
|
<DT><B>metacharacter</B>
|
|
|
|
<DD>
|
|
A character that, when unquoted, separates words. One of the following:
|
|
<BR>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>| & ; ( ) < > space tab newline</B>
|
|
|
|
</DL>
|
|
|
|
<DT><B>control operator</B>
|
|
|
|
<DD>
|
|
A <I>token</I> that performs a control function. It is one of the following
|
|
symbols:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>|| & && ; ;; ;& ;;& ( ) | |& <newline></B>
|
|
|
|
</DL>
|
|
|
|
|
|
</DL>
|
|
<A NAME="lbAJ"> </A>
|
|
<H3>RESERVED WORDS</H3>
|
|
|
|
<I>Reserved words</I> are words that have a special meaning to the shell.
|
|
The following words are recognized as reserved when unquoted and either
|
|
the first word of a command (see
|
|
<FONT SIZE=-1><B>SHELL GRAMMAR</B>
|
|
|
|
</FONT>
|
|
below), the third word of a
|
|
<B>case</B>
|
|
|
|
or
|
|
<B>select</B>
|
|
|
|
command
|
|
(only <B>in</B> is valid), or the third word of a
|
|
<B>for</B>
|
|
|
|
command (only <B>in</B> and <B>do</B> are valid):
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<P>
|
|
|
|
<B>
|
|
</B>
|
|
|
|
! case coproc do done elif else esac fi for function if in select then until while { } time [[ ]]
|
|
</DL>
|
|
|
|
|
|
<A NAME="lbAK"> </A>
|
|
<H3>SHELL GRAMMAR</H3>
|
|
|
|
This section describes the syntax of the various forms of shell commands.
|
|
<A NAME="lbAL"> </A>
|
|
<H4>Simple Commands</H4>
|
|
|
|
A <I>simple command</I> is a sequence of optional variable assignments
|
|
followed by <B>blank</B>-separated words and redirections, and
|
|
terminated by a <I>control operator</I>. The first word
|
|
specifies the command to be executed, and is passed as argument zero.
|
|
The remaining words are passed as arguments to the invoked command.
|
|
<P>
|
|
|
|
The return value of a <I>simple command</I> is its exit status, or
|
|
128+<I>n</I> if the command is terminated by signal
|
|
<I>n</I>.
|
|
|
|
<A NAME="lbAM"> </A>
|
|
<H4>Pipelines</H4>
|
|
|
|
A <I>pipeline</I> is a sequence of one or more commands separated by
|
|
one of the control operators
|
|
<B>|</B>
|
|
|
|
or <B>|&</B>.
|
|
The format for a pipeline is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<B>time</B> [<B>-p</B>]] [ ! ] <I>command1</I> [ [<B>|</B>|<B>|&</B>] <I>command2</I> ... ]
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
The standard output of
|
|
<I>command1</I>
|
|
|
|
is connected via a pipe to the standard input of
|
|
<I>command2</I>.
|
|
|
|
This connection is performed before any redirections specified by the
|
|
<I>command1</I>(see
|
|
|
|
<FONT SIZE=-1><B>REDIRECTION</B>
|
|
|
|
</FONT>
|
|
below).
|
|
If <B>|&</B> is used, <I>command1</I>'s standard error, in addition to its
|
|
standard output, is connected to
|
|
<I>command2</I>'s standard input through the pipe;
|
|
it is shorthand for <B>2>&1 |</B>.
|
|
This implicit redirection of the standard error to the standard output is
|
|
performed after any redirections specified by <I>command1</I>.
|
|
<P>
|
|
|
|
The return status of a pipeline is the exit status of the last
|
|
command, unless the <B>pipefail</B> option is enabled.
|
|
If <B>pipefail</B> is enabled, the pipeline's return status is the
|
|
value of the last (rightmost) command to exit with a non-zero status,
|
|
or zero if all commands exit successfully.
|
|
If the reserved word
|
|
<B>!</B>
|
|
|
|
precedes a pipeline, the exit status of that pipeline is the logical
|
|
negation of the exit status as described above.
|
|
The shell waits for all commands in the pipeline to
|
|
terminate before returning a value.
|
|
<P>
|
|
|
|
If the
|
|
<B>time</B>
|
|
|
|
reserved word precedes a pipeline, the elapsed as well as user and
|
|
system time consumed by its execution are reported when the pipeline
|
|
terminates.
|
|
The <B>-p</B> option changes the output format to that specified by POSIX.
|
|
When the shell is in <I>posix mode</I>, it does not recognize
|
|
<B>time</B> as a reserved word if the next token begins with a `-'.
|
|
The
|
|
<FONT SIZE=-1><B>TIMEFORMAT</B>
|
|
|
|
</FONT>
|
|
variable may be set to a format string that specifies how the timing
|
|
information should be displayed; see the description of
|
|
<FONT SIZE=-1><B>TIMEFORMAT</B>
|
|
|
|
</FONT>
|
|
under
|
|
<B>Shell Variables</B>
|
|
|
|
below.
|
|
<P>
|
|
|
|
When the shell is in <I>posix mode</I>, <B>time</B>
|
|
may be followed by a newline. In this case, the shell displays the
|
|
total user and system time consumed by the shell and its children.
|
|
The
|
|
<FONT SIZE=-1><B>TIMEFORMAT</B>
|
|
|
|
</FONT>
|
|
variable may be used to specify the format of
|
|
the time information.
|
|
<P>
|
|
|
|
Each command in a multi-command pipeline,
|
|
where pipes are created,
|
|
is executed in a <I>subshell</I>, which is a
|
|
separate process.
|
|
See
|
|
<FONT SIZE=-1><B>COMMAND EXECUTION ENVIRONMENT</B></FONT>
|
|
for a description of subshells and a subshell environment.
|
|
If the <B>lastpipe</B> option is enabled using the <B>shopt</B> builtin
|
|
(see the description of <B>shopt</B> below),
|
|
the last element of a pipeline may be run by the shell process
|
|
when job control is not active.
|
|
<A NAME="lbAN"> </A>
|
|
<H4>Lists</H4>
|
|
|
|
A <I>list</I> is a sequence of one or more pipelines separated by one
|
|
of the operators
|
|
<B>;</B>,
|
|
|
|
<B>&</B>,
|
|
|
|
<B>&&</B>,
|
|
|
|
or
|
|
<B>||</B>,
|
|
|
|
and optionally terminated by one of
|
|
<B>;</B>,
|
|
|
|
<B>&</B>,
|
|
|
|
or
|
|
<B><newline></B>.
|
|
|
|
<P>
|
|
|
|
Of these list operators,
|
|
<B>&&</B>
|
|
|
|
and
|
|
<B>||</B>
|
|
|
|
have equal precedence, followed by
|
|
<B>;</B>
|
|
|
|
and
|
|
<B>&</B>,
|
|
|
|
which have equal precedence.
|
|
<P>
|
|
|
|
A sequence of one or more newlines may appear in a <I>list</I> instead
|
|
of a semicolon to delimit commands.
|
|
<P>
|
|
|
|
If a command is terminated by the control operator
|
|
<B>&</B>,
|
|
|
|
the shell executes the command in the <I>background</I>
|
|
in a subshell.
|
|
The shell does not wait for the command to
|
|
finish, and the return status is 0.
|
|
These are referred to as <I>asynchronous</I> commands.
|
|
Commands separated by a
|
|
<B>;</B>
|
|
|
|
are executed sequentially; the shell waits for each
|
|
command to terminate in turn. The return status is the
|
|
exit status of the last command executed.
|
|
<P>
|
|
|
|
AND and OR lists are sequences of one or more pipelines separated by the
|
|
<B>&&</B> and <B>||</B> control operators, respectively.
|
|
AND and OR lists are executed with left associativity.
|
|
An AND list has the form
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<I>command1</I> <B>&&</B> <I>command2</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
<I>command2</I>
|
|
|
|
is executed if, and only if,
|
|
<I>command1</I>
|
|
|
|
returns an exit status of zero (success).
|
|
<P>
|
|
|
|
An OR list has the form
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<I>command1</I> <B>||</B> <I>command2</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
<I>command2</I>
|
|
|
|
is executed if, and only if,
|
|
<I>command1</I>
|
|
|
|
returns a non-zero exit status.
|
|
The return status of
|
|
AND and OR lists is the exit status of the last command
|
|
executed in the list.
|
|
<A NAME="lbAO"> </A>
|
|
<H4>Compound Commands</H4>
|
|
|
|
A <I>compound command</I> is one of the following.
|
|
In most cases a <I>list</I> in a command's description may be separated from
|
|
the rest of the command by one or more newlines, and may be followed by a
|
|
newline in place of a semicolon.
|
|
<DL COMPACT>
|
|
<DT>(<I>list</I>)<DD>
|
|
<I>list</I> is executed in a subshell (see
|
|
<FONT SIZE=-1><B>COMMAND EXECUTION ENVIRONMENT</B></FONT>
|
|
below for a description of a subshell environment).
|
|
Variable assignments and builtin
|
|
commands that affect the shell's environment do not remain in effect
|
|
after the command completes. The return status is the exit status of
|
|
<I>list</I>.
|
|
<DT>{ <I>list</I>; }<DD>
|
|
<I>list</I> is simply executed in the current shell environment.
|
|
<I>list</I> must be terminated with a newline or semicolon.
|
|
This is known as a <I>group command</I>.
|
|
The return status is the exit status of
|
|
<I>list</I>.
|
|
Note that unlike the metacharacters <B>(</B> and <B>)</B>, <B>{</B> and
|
|
<B>}</B> are <I>reserved words</I> and must occur where a reserved
|
|
word is permitted to be recognized. Since they do not cause a word
|
|
break, they must be separated from <I>list</I> by whitespace or another
|
|
shell metacharacter.
|
|
<DT>((<I>expression</I>))<DD>
|
|
The <I>expression</I> is evaluated according to the rules described
|
|
below under
|
|
<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>.
|
|
|
|
</FONT>
|
|
If the value of the expression is non-zero, the return status is 0;
|
|
otherwise the return status is 1.
|
|
The <I>expression</I>
|
|
undergoes the same expansions
|
|
as if it were within double quotes,
|
|
but double quote characters in <I>expression</I> are not treated specially
|
|
and are removed.
|
|
<DT><B>[[</B> <I>expression</I> <B>]]</B><DD>
|
|
Return a status of 0 or 1 depending on the evaluation of
|
|
the conditional expression <I>expression</I>.
|
|
Expressions are composed of the primaries described below under
|
|
<FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>.
|
|
|
|
</FONT>
|
|
The words between the <B>[[</B> and <B>]]</B> do not undergo word splitting
|
|
and pathname expansion.
|
|
The shell performs tilde expansion, parameter and
|
|
variable expansion, arithmetic expansion, command substitution, process
|
|
substitution, and quote removal on those words
|
|
(the expansions that would occur if the words were enclosed in double quotes).
|
|
Conditional operators such as <B>-f</B> must be unquoted to be recognized
|
|
as primaries.
|
|
<P>
|
|
|
|
|
|
When used with <B>[[</B>, the <B><</B> and <B>></B> operators sort
|
|
lexicographically using the current locale.
|
|
<P>
|
|
|
|
|
|
When the <B>==</B> and <B>!=</B> operators are used, the string to the
|
|
right of the operator is considered a pattern and matched according
|
|
to the rules described below under <B>Pattern Matching</B>,
|
|
as if the <B>extglob</B> shell option were enabled.
|
|
The <B>=</B> operator is equivalent to <B>==</B>.
|
|
If the
|
|
<B>nocasematch</B>
|
|
|
|
shell option is enabled, the match is performed without regard to the case
|
|
of alphabetic characters.
|
|
The return value is 0 if the string matches (<B>==</B>) or does not match
|
|
(<B>!=</B>) the pattern, and 1 otherwise.
|
|
Any part of the pattern may be quoted to force the quoted portion
|
|
to be matched as a string.
|
|
<P>
|
|
|
|
|
|
An additional binary operator, <B>=~</B>, is available, with the same
|
|
precedence as <B>==</B> and <B>!=</B>.
|
|
When it is used, the string to the right of the operator is considered
|
|
a POSIX extended regular expression and matched accordingly
|
|
(using the POSIX <I>regcomp</I> and <I>regexec</I> interfaces
|
|
usually described in <I>regex</I>(3)).
|
|
The return value is 0 if the string matches
|
|
the pattern, and 1 otherwise.
|
|
If the regular expression is syntactically incorrect, the conditional
|
|
expression's return value is 2.
|
|
If the
|
|
<B>nocasematch</B>
|
|
|
|
shell option is enabled, the match is performed without regard to the case
|
|
of alphabetic characters.
|
|
If any part of the pattern is quoted, the quoted portion is matched literally.
|
|
This means every character in the quoted portion matches itself,
|
|
instead of having any special pattern matching meaning.
|
|
If the pattern is stored in a shell variable, quoting the variable
|
|
expansion forces the entire pattern to be matched literally.
|
|
Treat bracket expressions in regular expressions carefully,
|
|
since normal quoting and pattern characters lose their meanings
|
|
between brackets.
|
|
<P>
|
|
|
|
|
|
The pattern will match if it matches any part of the string.
|
|
Anchor the pattern using the <B>^</B> and <B>$</B> regular expression
|
|
operators to force it to match the entire string.
|
|
The array variable
|
|
<FONT SIZE=-1><B>BASH_REMATCH</B>
|
|
|
|
</FONT>
|
|
records which parts of the string matched the pattern.
|
|
The element of
|
|
<FONT SIZE=-1><B>BASH_REMATCH</B>
|
|
|
|
</FONT>
|
|
with index 0 contains the portion of
|
|
the string matching the entire regular expression.
|
|
Substrings matched by parenthesized subexpressions within the regular
|
|
expression are saved in the remaining
|
|
<FONT SIZE=-1><B>BASH_REMATCH</B>
|
|
|
|
</FONT>
|
|
indices. The element of
|
|
<FONT SIZE=-1><B>BASH_REMATCH</B>
|
|
|
|
</FONT>
|
|
with index <I>n</I> is the portion of the
|
|
string matching the <I>n</I>th parenthesized subexpression.
|
|
Bash sets
|
|
<FONT SIZE=-1><B>BASH_REMATCH</B>
|
|
|
|
</FONT>
|
|
in the global scope; declaring it as a local variable will lead to
|
|
unexpected results.
|
|
<P>
|
|
|
|
|
|
Expressions may be combined using the following operators, listed
|
|
in decreasing order of precedence:
|
|
<P>
|
|
|
|
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>( </B><I>expression</I> )
|
|
|
|
<DD>
|
|
Returns the value of <I>expression</I>.
|
|
This may be used to override the normal precedence of operators.
|
|
<DT><B>! </B><I>expression</I>
|
|
|
|
<DD>
|
|
True if
|
|
<I>expression</I>
|
|
|
|
is false.
|
|
<DT><I>expression1</I> <B>&&</B> <I>expression2</I><DD>
|
|
True if both
|
|
<I>expression1</I>
|
|
|
|
and
|
|
<I>expression2</I>
|
|
|
|
are true.
|
|
<DT><I>expression1</I> <B>||</B> <I>expression2</I><DD>
|
|
True if either
|
|
<I>expression1</I>
|
|
|
|
or
|
|
<I>expression2</I>
|
|
|
|
is true.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The <B>&&</B> and <B>||</B>
|
|
operators do not evaluate <I>expression2</I> if the value of
|
|
<I>expression1</I> is sufficient to determine the return value of
|
|
the entire conditional expression.
|
|
</DL>
|
|
|
|
<DT><B>for</B> <I>name</I> [ [ <B>in</B> [ <I>word ...</I> ] ] ; ] <B>do</B> <I>list</I> ; <B>done</B><DD>
|
|
The list of words following <B>in</B> is expanded, generating a list
|
|
of items.
|
|
The variable <I>name</I> is set to each element of this list
|
|
in turn, and <I>list</I> is executed each time.
|
|
If the <B>in</B> <I>word</I> is omitted, the <B>for</B> command executes
|
|
<I>list</I> once for each positional parameter that is set (see
|
|
<FONT SIZE=-1><B>PARAMETERS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
The return status is the exit status of the last command that executes.
|
|
If the expansion of the items following <B>in</B> results in an empty
|
|
list, no commands are executed, and the return status is 0.
|
|
<DT><B>for</B> (( <I>expr1</I> ; <I>expr2</I> ; <I>expr3</I> )) ; <B>do</B> <I>list</I> ; <B>done</B><DD>
|
|
First, the arithmetic expression <I>expr1</I> is evaluated according
|
|
to the rules described below under
|
|
<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>.
|
|
|
|
</FONT>
|
|
The arithmetic expression <I>expr2</I> is then evaluated repeatedly
|
|
until it evaluates to zero.
|
|
Each time <I>expr2</I> evaluates to a non-zero value, <I>list</I> is
|
|
executed and the arithmetic expression <I>expr3</I> is evaluated.
|
|
If any expression is omitted, it behaves as if it evaluates to 1.
|
|
The return value is the exit status of the last command in <I>list</I>
|
|
that is executed, or false if any of the expressions is invalid.
|
|
<DT><B>select</B> <I>name</I> [ <B>in</B> <I>word</I> ] ; <B>do</B> <I>list</I> ; <B>done</B><DD>
|
|
The list of words following <B>in</B> is expanded, generating a list
|
|
of items, and the set of expanded words is printed on the standard
|
|
error, each preceded by a number. If the <B>in</B>
|
|
<I>word</I> is omitted, the positional parameters are printed (see
|
|
<FONT SIZE=-1><B>PARAMETERS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<B>select</B>
|
|
|
|
then displays the
|
|
<FONT SIZE=-1><B>PS3</B>
|
|
|
|
</FONT>
|
|
prompt and reads a line from the standard input.
|
|
If the line consists of a number corresponding to one of
|
|
the displayed words, then the value of
|
|
<I>name</I>
|
|
|
|
is set to that word.
|
|
If the line is empty, the words and prompt are displayed again.
|
|
If EOF is read, the <B>select</B> command completes and returns 1.
|
|
Any other value read causes
|
|
<I>name</I>
|
|
|
|
to be set to null. The line read is saved in the variable
|
|
<FONT SIZE=-1><B>REPLY</B>.
|
|
|
|
</FONT>
|
|
The
|
|
<I>list</I>
|
|
|
|
is executed after each selection until a
|
|
<B>break</B>
|
|
|
|
command is executed.
|
|
The exit status of
|
|
<B>select</B>
|
|
|
|
is the exit status of the last command executed in
|
|
<I>list</I>,
|
|
|
|
or zero if no commands were executed.
|
|
<DT><B>case</B> <I>word</I> <B>in</B> [ [(] <I>pattern</I> [ <B>|</B> <I>pattern</I> ]
|
|
<DD>
|
|
A <B>case</B> command first expands <I>word</I>, and tries to match
|
|
it against each <I>pattern</I> in turn, using the matching rules
|
|
described under
|
|
<B>Pattern Matching</B>
|
|
|
|
below.
|
|
The <I>word</I> is expanded using tilde
|
|
expansion, parameter and variable expansion, arithmetic expansion,
|
|
command substitution, process substitution and quote removal.
|
|
Each <I>pattern</I> examined is expanded using tilde
|
|
expansion, parameter and variable expansion, arithmetic expansion,
|
|
command substitution, process substitution, and quote removal.
|
|
If the
|
|
<B>nocasematch</B>
|
|
|
|
shell option is enabled, the match is performed without regard to the case
|
|
of alphabetic characters.
|
|
When a match is found, the corresponding <I>list</I> is executed.
|
|
If the <B>;;</B> operator is used, no subsequent matches are attempted after
|
|
the first pattern match.
|
|
Using <B>;&</B> in place of <B>;;</B> causes execution to continue with
|
|
the <I>list</I> associated with the next set of patterns.
|
|
Using <B>;;&</B> in place of <B>;;</B> causes the shell to test the next
|
|
pattern list in the statement, if any, and execute any associated <I>list</I>
|
|
on a successful match,
|
|
continuing the case statement execution as if the pattern list had not matched.
|
|
The exit status is zero if no
|
|
pattern matches. Otherwise, it is the exit status of the
|
|
last command executed in <I>list</I>.
|
|
<DT><B>if</B> <I>list</I>; <B>then</B> <I>list</I>; [ <B>elif</B> <I>list</I>; <B>then</B> <I>list</I>; ] ... [ <B>else</B> <I>list</I>; ] <B>fi</B><DD>
|
|
The
|
|
<B>if</B>
|
|
|
|
<I>list</I>
|
|
|
|
is executed. If its exit status is zero, the
|
|
<B>then</B> <I>list</I> is executed. Otherwise, each <B>elif</B>
|
|
<I>list</I> is executed in turn, and if its exit status is zero,
|
|
the corresponding <B>then</B> <I>list</I> is executed and the
|
|
command completes. Otherwise, the <B>else</B> <I>list</I> is
|
|
executed, if present. The exit status is the exit status of the
|
|
last command executed, or zero if no condition tested true.
|
|
<DT><B>while</B> <I>list-1</I>; <B>do</B> <I>list-2</I>; <B>done</B><DD>
|
|
|
|
<DT><B>until</B> <I>list-1</I>; <B>do</B> <I>list-2</I>; <B>done</B><DD>
|
|
|
|
The <B>while</B> command continuously executes the list
|
|
<I>list-2</I> as long as the last command in the list <I>list-1</I> returns
|
|
an exit status of zero. The <B>until</B> command is identical
|
|
to the <B>while</B> command, except that the test is negated:
|
|
<I>list-2</I>
|
|
|
|
is executed as long as the last command in
|
|
<I>list-1</I>
|
|
|
|
returns a non-zero exit status.
|
|
The exit status of the <B>while</B> and <B>until</B> commands
|
|
is the exit status
|
|
of the last command executed in <I>list-2</I>, or zero if
|
|
none was executed.
|
|
</DL>
|
|
<A NAME="lbAP"> </A>
|
|
<H4>Coprocesses</H4>
|
|
|
|
A <I>coprocess</I> is a shell command preceded by the <B>coproc</B> reserved
|
|
word.
|
|
A coprocess is executed asynchronously in a subshell, as if the command
|
|
had been terminated with the <B>&</B> control operator, with a two-way pipe
|
|
established between the executing shell and the coprocess.
|
|
<P>
|
|
|
|
The syntax for a coprocess is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>coproc</B> [<I>NAME</I>] <I>command</I> [<I>redirections</I>]
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
This creates a coprocess named <I>NAME</I>.
|
|
<I>command</I> may be either a simple command or a compound
|
|
command (see above).
|
|
<I>NAME</I> is a shell variable name.
|
|
If <I>NAME</I> is not supplied, the default name is <B>COPROC</B>.
|
|
<P>
|
|
|
|
The recommended form to use for a coprocess is
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>coproc</B> <I>NAME</I> { <I>command</I> [<I>redirections</I>]; }
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
This form is recommended because simple commands result in the coprocess
|
|
always being named <B>COPROC</B>, and it is simpler to use and more complete
|
|
than the other compound commands.
|
|
<P>
|
|
|
|
If <I>command</I> is a compound command, <I>NAME</I> is optional. The
|
|
word following <B>coproc</B> determines whether that word is interpreted
|
|
as a variable name: it is interpreted as <I>NAME</I> if it is not a
|
|
reserved word that introduces a compound command.
|
|
If <I>command</I> is a simple command, <I>NAME</I> is not allowed; this
|
|
is to avoid confusion between <I>NAME</I> and the first word of the simple
|
|
command.
|
|
<P>
|
|
|
|
When the coprocess is executed, the shell creates an array variable (see
|
|
<B>Arrays</B>
|
|
|
|
below) named <I>NAME</I> in the context of the executing shell.
|
|
The standard output of
|
|
<I>command</I>
|
|
|
|
is connected via a pipe to a file descriptor in the executing shell,
|
|
and that file descriptor is assigned to <I>NAME</I>[0].
|
|
The standard input of
|
|
<I>command</I>
|
|
|
|
is connected via a pipe to a file descriptor in the executing shell,
|
|
and that file descriptor is assigned to <I>NAME</I>[1].
|
|
This pipe is established before any redirections specified by the
|
|
command (see
|
|
<FONT SIZE=-1><B>REDIRECTION</B>
|
|
|
|
</FONT>
|
|
below).
|
|
The file descriptors can be utilized as arguments to shell commands
|
|
and redirections using standard word expansions.
|
|
Other than those created to execute command and process substitutions,
|
|
the file descriptors are not available in subshells.
|
|
<P>
|
|
|
|
The process ID of the shell spawned to execute the coprocess is
|
|
available as the value of the variable <I>NAME</I>_PID.
|
|
The <B>wait</B>
|
|
builtin command may be used to wait for the coprocess to terminate.
|
|
<P>
|
|
|
|
Since the coprocess is created as an asynchronous command,
|
|
the <B>coproc</B> command always returns success.
|
|
The return status of a coprocess is the exit status of <I>command</I>.
|
|
<A NAME="lbAQ"> </A>
|
|
<H4>Shell Function Definitions</H4>
|
|
|
|
A shell function is an object that is called like a simple command and
|
|
executes a compound command with a new set of positional parameters.
|
|
Shell functions are declared as follows:
|
|
<DL COMPACT>
|
|
<DT><I>fname</I> () <I>compound-command</I> [<I>redirection</I>]<DD>
|
|
|
|
<DT><B>function</B> <I>fname</I> [()] <I>compound-command</I> [<I>redirection</I>]<DD>
|
|
|
|
This defines a function named <I>fname</I>.
|
|
The reserved word <B>function</B> is optional.
|
|
If the <B>function</B> reserved word is supplied, the parentheses are optional.
|
|
The <I>body</I> of the function is the compound command
|
|
<I>compound-command</I>
|
|
|
|
(see <B>Compound Commands</B> above).
|
|
That command is usually a <I>list</I> of commands between { and }, but
|
|
may be any command listed under <B>Compound Commands</B> above.
|
|
If the <B>function</B> reserved word is used, but the
|
|
parentheses are not supplied, the braces are recommended.
|
|
<I>compound-command</I> is executed whenever <I>fname</I> is specified as the
|
|
name of a simple command.
|
|
When in <I>posix mode</I>, <I>fname</I> must be a valid shell <I>name</I>
|
|
and may not be the name of one of the
|
|
POSIX <I>special builtins</I>.
|
|
In default mode, a function name can be any unquoted shell word that does
|
|
not contain <B>$</B>.
|
|
Any redirections (see
|
|
<FONT SIZE=-1><B>REDIRECTION</B>
|
|
|
|
</FONT>
|
|
below) specified when a function is defined are performed
|
|
when the function is executed.
|
|
The exit status of a function definition is zero unless a syntax error
|
|
occurs or a readonly function with the same name already exists.
|
|
When executed, the exit status of a function is the exit status of the
|
|
last command executed in the body. (See
|
|
<FONT SIZE=-1><B>FUNCTIONS</B>
|
|
|
|
</FONT>
|
|
below.)
|
|
</DL>
|
|
<A NAME="lbAR"> </A>
|
|
<H3>COMMENTS</H3>
|
|
|
|
In a non-interactive shell, or an interactive shell in which the
|
|
<B>interactive_comments</B>
|
|
|
|
option to the
|
|
<B>shopt</B>
|
|
|
|
builtin is enabled (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below), a word beginning with
|
|
<B>#</B>
|
|
|
|
causes that word and all remaining characters on that line to
|
|
be ignored. An interactive shell without the
|
|
<B>interactive_comments</B>
|
|
|
|
option enabled does not allow comments. The
|
|
<B>interactive_comments</B>
|
|
|
|
option is on by default in interactive shells.
|
|
<A NAME="lbAS"> </A>
|
|
<H3>QUOTING</H3>
|
|
|
|
<I>Quoting</I> is used to remove the special meaning of certain
|
|
characters or words to the shell. Quoting can be used to
|
|
disable special treatment for special characters, to prevent
|
|
reserved words from being recognized as such, and to prevent
|
|
parameter expansion.
|
|
<P>
|
|
|
|
Each of the <I>metacharacters</I> listed above under
|
|
<FONT SIZE=-1><B>DEFINITIONS</B>
|
|
|
|
</FONT>
|
|
has special meaning to the shell and must be quoted if it is to
|
|
represent itself.
|
|
<P>
|
|
|
|
When the command history expansion facilities are being used
|
|
(see
|
|
<FONT SIZE=-1><B>HISTORY EXPANSION</B>
|
|
|
|
</FONT>
|
|
below), the
|
|
<I>history expansion</I> character, usually <B>!</B>, must be quoted
|
|
to prevent history expansion.
|
|
<P>
|
|
|
|
There are three quoting mechanisms: the
|
|
<I>escape character</I>,
|
|
|
|
single quotes, and double quotes.
|
|
<P>
|
|
|
|
A non-quoted backslash (<B>\</B>) is the
|
|
<I>escape character</I>.
|
|
|
|
It preserves the literal value of the next character that follows,
|
|
with the exception of <newline>. If a <B>\</B><newline> pair
|
|
appears, and the backslash is not itself quoted, the <B>\</B><newline>
|
|
is treated as a line continuation (that is, it is removed from the
|
|
input stream and effectively ignored).
|
|
<P>
|
|
|
|
Enclosing characters in single quotes preserves the literal value
|
|
of each character within the quotes. A single quote may not occur
|
|
between single quotes, even when preceded by a backslash.
|
|
<P>
|
|
|
|
Enclosing characters in double quotes preserves the literal value
|
|
of all characters within the quotes, with the exception of
|
|
<B>$</B>,
|
|
|
|
<B>`</B>,
|
|
|
|
<B>\</B>,
|
|
|
|
and, when history expansion is enabled,
|
|
<B>!</B>.
|
|
|
|
When the shell is in <I>posix mode</I>, the <B>!</B> has no special meaning
|
|
within double quotes, even when history expansion is enabled.
|
|
The characters
|
|
<B>$</B>
|
|
|
|
and
|
|
<B>`</B>
|
|
|
|
retain their special meaning within double quotes. The backslash
|
|
retains its special meaning only when followed by one of the following
|
|
characters:
|
|
<B>$</B>,
|
|
|
|
<B>`</B>,
|
|
|
|
<B>"</B>,
|
|
<B>\</B>,
|
|
|
|
or
|
|
<B><newline></B>.
|
|
|
|
A double quote may be quoted within double quotes by preceding it with
|
|
a backslash.
|
|
If enabled, history expansion will be performed unless an
|
|
<B>!</B>
|
|
|
|
appearing in double quotes is escaped using a backslash.
|
|
The backslash preceding the
|
|
<B>!</B>
|
|
|
|
is not removed.
|
|
<P>
|
|
|
|
The special parameters
|
|
<B>*</B>
|
|
|
|
and
|
|
<B>@</B>
|
|
|
|
have special meaning when in double
|
|
quotes (see
|
|
<FONT SIZE=-1><B>PARAMETERS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<P>
|
|
|
|
Character sequences of the form <B>$</B>aq<I>string</I>aq are treated
|
|
as a special variant of single quotes.
|
|
The sequence expands to <I>string</I>, with backslash-escaped characters
|
|
in <I>string</I> replaced as specified by the ANSI C standard.
|
|
Backslash escape sequences, if present, are decoded as follows:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>\a</B>
|
|
|
|
<DD>
|
|
alert (bell)
|
|
<DT><B>\b</B>
|
|
|
|
<DD>
|
|
backspace
|
|
<DT><B>\e</B>
|
|
|
|
<DD>
|
|
<DT><B>\E</B>
|
|
|
|
<DD>
|
|
an escape character
|
|
<DT><B>\f</B>
|
|
|
|
<DD>
|
|
form feed
|
|
<DT><B>\n</B>
|
|
|
|
<DD>
|
|
new line
|
|
<DT><B>\r</B>
|
|
|
|
<DD>
|
|
carriage return
|
|
<DT><B>\t</B>
|
|
|
|
<DD>
|
|
horizontal tab
|
|
<DT><B>\v</B>
|
|
|
|
<DD>
|
|
vertical tab
|
|
<DT><B>\\</B>
|
|
|
|
<DD>
|
|
backslash
|
|
<DT><B>\aq</B>
|
|
|
|
<DD>
|
|
single quote
|
|
<DT><B>\dq</B>
|
|
|
|
<DD>
|
|
double quote
|
|
<DT><B>\?</B>
|
|
|
|
<DD>
|
|
question mark
|
|
<DT><B>\</B><I>nnn</I>
|
|
|
|
<DD>
|
|
the eight-bit character whose value is the octal value <I>nnn</I>
|
|
(one to three octal digits)
|
|
<DT><B>\x</B><I>HH</I>
|
|
|
|
<DD>
|
|
the eight-bit character whose value is the hexadecimal value <I>HH</I>
|
|
(one or two hex digits)
|
|
<DT><B>\u</B><I>HHHH</I>
|
|
|
|
<DD>
|
|
the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
|
|
<I>HHHH</I> (one to four hex digits)
|
|
<DT><B>\U</B><I>HHHHHHHH</I>
|
|
|
|
<DD>
|
|
the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
|
|
<I>HHHHHHHH</I> (one to eight hex digits)
|
|
<DT><B>\c</B><I>x</I>
|
|
|
|
<DD>
|
|
a control-<I>x</I> character
|
|
|
|
</DL></DL>
|
|
|
|
<P>
|
|
|
|
The expanded result is single-quoted, as if the dollar sign had
|
|
not been present.
|
|
<P>
|
|
|
|
A double-quoted string preceded by a dollar sign (<B>$</B>dq<I>string</I>dq)
|
|
will cause the string to be translated according to the current locale.
|
|
The <I>gettext</I> infrastructure performs the lookup and
|
|
translation, using the <B>LC_MESSAGES</B>, <B>TEXTDOMAINDIR</B>,
|
|
and <B>TEXTDOMAIN</B> shell variables.
|
|
If the current locale is <B>C</B> or <B>POSIX</B>,
|
|
if there are no translations available,
|
|
or if the string is not translated,
|
|
the dollar sign is ignored.
|
|
This is a form of double quoting, so the string remains double-quoted
|
|
by default, whether or not it is translated and replaced.
|
|
If the <B>noexpand_translation</B> option is enabled
|
|
using the <B>shopt</B> builtin,
|
|
translated strings are single-quoted instead of double-quoted.
|
|
See the description of
|
|
<B>shopt</B>
|
|
|
|
below under
|
|
<FONT SIZE=-1><B>SHELL</B>BUILTIN<B>COMMANDS</B>.
|
|
|
|
</FONT>
|
|
<A NAME="lbAT"> </A>
|
|
<H3>PARAMETERS</H3>
|
|
|
|
A
|
|
<I>parameter</I>
|
|
|
|
is an entity that stores values.
|
|
It can be a
|
|
<I>name</I>,
|
|
|
|
a number, or one of the special characters listed below under
|
|
<B>Special Parameters</B>.
|
|
|
|
A
|
|
<I>variable</I>
|
|
|
|
is a parameter denoted by a
|
|
<I>name</I>.
|
|
|
|
A variable has a <I>value</I> and zero or more <I>attributes</I>.
|
|
Attributes are assigned using the
|
|
<B>declare</B>
|
|
|
|
builtin command (see
|
|
<B>declare</B>
|
|
|
|
below in
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>).
|
|
|
|
</FONT>
|
|
<P>
|
|
|
|
A parameter is set if it has been assigned a value. The null string is
|
|
a valid value. Once a variable is set, it may be unset only by using
|
|
the
|
|
<B>unset</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<P>
|
|
|
|
A
|
|
<I>variable</I>
|
|
|
|
may be assigned to by a statement of the form
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<I>name</I>=[<I>value</I>]
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
If
|
|
<I>value</I>
|
|
|
|
is not given, the variable is assigned the null string. All
|
|
<I>values</I>
|
|
|
|
undergo tilde expansion, parameter and variable expansion,
|
|
command substitution, arithmetic expansion, and quote
|
|
removal (see
|
|
<FONT SIZE=-1><B>EXPANSION</B>
|
|
|
|
</FONT>
|
|
below). If the variable has its
|
|
<B>integer</B>
|
|
|
|
attribute set, then
|
|
<I>value</I>
|
|
|
|
is evaluated as an arithmetic expression even if the $((...)) expansion is
|
|
not used (see
|
|
<B>Arithmetic Expansion</B>
|
|
|
|
below).
|
|
Word splitting and pathname expansion are not performed.
|
|
Assignment statements may also appear as arguments to the
|
|
<B>alias</B>,
|
|
|
|
<B>declare</B>,
|
|
|
|
<B>typeset</B>,
|
|
|
|
<B>export</B>,
|
|
|
|
<B>readonly</B>,
|
|
|
|
and
|
|
<B>local</B>
|
|
|
|
builtin commands (<I>declaration</I> commands).
|
|
When in <I>posix mode</I>, these builtins may appear in a command after
|
|
one or more instances of the <B>command</B> builtin and retain these
|
|
assignment statement properties.
|
|
<P>
|
|
|
|
In the context where an assignment statement is assigning a value
|
|
to a shell variable or array index, the += operator can be used to
|
|
append to or add to the variable's previous value.
|
|
This includes arguments to builtin commands such as <B>declare</B> that
|
|
accept assignment statements (<I>declaration</I> commands).
|
|
When += is applied to a variable for which the <B>integer</B> attribute has been
|
|
set, <I>value</I> is evaluated as an arithmetic expression and added to the
|
|
variable's current value, which is also evaluated.
|
|
When += is applied to an array variable using compound assignment (see
|
|
<B>Arrays</B>
|
|
|
|
below), the
|
|
variable's value is not unset (as it is when using =), and new values are
|
|
appended to the array beginning at one greater than the array's maximum index
|
|
(for indexed arrays) or added as additional key-value pairs in an
|
|
associative array.
|
|
When applied to a string-valued variable, <I>value</I> is expanded and
|
|
appended to the variable's value.
|
|
<P>
|
|
|
|
A variable can be assigned the <I>nameref</I> attribute using the
|
|
<B>-n</B> option to the <B>declare</B> or <B>local</B> builtin commands
|
|
(see the descriptions of <B>declare</B> and <B>local</B> below)
|
|
to create a <I>nameref</I>, or a reference to another variable.
|
|
This allows variables to be manipulated indirectly.
|
|
Whenever the nameref variable is referenced, assigned to, unset, or has
|
|
its attributes modified (other than using or changing the <I>nameref</I>
|
|
attribute itself), the
|
|
operation is actually performed on the variable specified by the nameref
|
|
variable's value.
|
|
A nameref is commonly used within shell functions to refer to a variable
|
|
whose name is passed as an argument to the function.
|
|
For instance, if a variable name is passed to a shell function as its first
|
|
argument, running
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
<TT>declare -n ref=$1</TT>
|
|
|
|
</DL>
|
|
|
|
<P>
|
|
inside the function creates a nameref variable <B>ref</B> whose value is
|
|
the variable name passed as the first argument.
|
|
References and assignments to <B>ref</B>, and changes to its attributes,
|
|
are treated as references, assignments, and attribute modifications
|
|
to the variable whose name was passed as <B>$1</B>.
|
|
If the control variable in a <B>for</B> loop has the nameref attribute,
|
|
the list of words can be a list of shell variables, and a name reference
|
|
will be established for each word in the list, in turn, when the loop is
|
|
executed.
|
|
Array variables cannot be given the <B>nameref</B> attribute.
|
|
However, nameref variables can reference array variables and subscripted
|
|
array variables.
|
|
Namerefs can be unset using the <B>-n</B> option to the <B>unset</B> builtin.
|
|
Otherwise, if <B>unset</B> is executed with the name of a nameref variable
|
|
as an argument, the variable referenced by the nameref variable will be unset.
|
|
<A NAME="lbAU"> </A>
|
|
<H4>Positional Parameters</H4>
|
|
|
|
A
|
|
<I>positional parameter</I>
|
|
|
|
is a parameter denoted by one or more
|
|
digits, other than the single digit 0. Positional parameters are
|
|
assigned from the shell's arguments when it is invoked,
|
|
and may be reassigned using the
|
|
<B>set</B>
|
|
|
|
builtin command. Positional parameters may not be assigned to
|
|
with assignment statements. The positional parameters are
|
|
temporarily replaced when a shell function is executed (see
|
|
<FONT SIZE=-1><B>FUNCTIONS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<P>
|
|
|
|
When a positional parameter consisting of more than a single
|
|
digit is expanded, it must be enclosed in braces (see
|
|
<FONT SIZE=-1><B>EXPANSION</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<A NAME="lbAV"> </A>
|
|
<H4>Special Parameters</H4>
|
|
|
|
The shell treats several parameters specially. These parameters may
|
|
only be referenced; assignment to them is not allowed.
|
|
|
|
<DL COMPACT>
|
|
<DT><B>*</B>
|
|
|
|
<DD>
|
|
Expands to the positional parameters, starting from one.
|
|
When the expansion is not within double quotes, each positional parameter
|
|
expands to a separate word.
|
|
In contexts where it is performed, those words
|
|
are subject to further word splitting and pathname expansion.
|
|
When the expansion occurs within double quotes, it expands to a single word
|
|
with the value of each parameter separated by the first character of the
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
special variable. That is, "<B>$*</B>" is equivalent
|
|
to "<B>$1</B><I>c</I><B>$2</B><I>c</I><B>...</B>", where
|
|
<I>c</I>
|
|
|
|
is the first character of the value of the
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
variable. If
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
is unset, the parameters are separated by spaces.
|
|
If
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
is null, the parameters are joined without intervening separators.
|
|
<DT><B>@</B>
|
|
|
|
<DD>
|
|
Expands to the positional parameters, starting from one.
|
|
In contexts where word splitting is performed, this expands each
|
|
positional parameter to a separate word; if not within double
|
|
quotes, these words are subject to word splitting.
|
|
In contexts where word splitting is not performed,
|
|
this expands to a single word
|
|
with each positional parameter separated by a space.
|
|
When the
|
|
expansion occurs within double quotes, each parameter expands to a
|
|
separate word. That is, "<B>$@</B>" is equivalent to
|
|
"<B>$1</B>" "<B>$2</B>" ...
|
|
If the double-quoted expansion occurs within a word, the expansion of
|
|
the first parameter is joined with the beginning part of the original
|
|
word, and the expansion of the last parameter is joined with the last
|
|
part of the original word.
|
|
When there are no positional parameters, "<B>$@</B>" and
|
|
<B>$@</B>
|
|
|
|
expand to nothing (i.e., they are removed).
|
|
<DT><B>#</B>
|
|
|
|
<DD>
|
|
Expands to the number of positional parameters in decimal.
|
|
<DT><B>?</B>
|
|
|
|
<DD>
|
|
Expands to the exit status of the most recently executed foreground
|
|
pipeline.
|
|
<DT><B>-</B>
|
|
|
|
<DD>
|
|
Expands to the current option flags as specified upon invocation,
|
|
by the
|
|
<B>set</B>
|
|
|
|
builtin command, or those set by the shell itself
|
|
(such as the
|
|
<B>-i</B>
|
|
|
|
option).
|
|
<DT><B>$</B>
|
|
|
|
<DD>
|
|
Expands to the process ID of the shell. In a subshell, it
|
|
expands to the process ID of the current shell, not the
|
|
subshell.
|
|
<DT><B>!</B>
|
|
|
|
<DD>
|
|
Expands to the process ID of the job most recently placed into the
|
|
background, whether executed as an asynchronous command or using
|
|
the <B>bg</B> builtin (see
|
|
<FONT SIZE=-1><B>JOB CONTROL</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<DT><B>0</B>
|
|
|
|
<DD>
|
|
Expands to the name of the shell or shell script. This is set at
|
|
shell initialization. If
|
|
<B>bash</B>
|
|
|
|
is invoked with a file of commands,
|
|
<B>$0</B>
|
|
|
|
is set to the name of that file. If
|
|
<B>bash</B>
|
|
|
|
is started with the
|
|
<B>-c</B>
|
|
|
|
option, then
|
|
<B>$0</B>
|
|
|
|
is set to the first argument after the string to be
|
|
executed, if one is present. Otherwise, it is set
|
|
to the filename used to invoke
|
|
<B>bash</B>,
|
|
|
|
as given by argument zero.
|
|
|
|
</DL>
|
|
<A NAME="lbAW"> </A>
|
|
<H4>Shell Variables</H4>
|
|
|
|
The following variables are set by the shell:
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>_</B>
|
|
|
|
<DD>
|
|
At shell startup, set to the pathname used to invoke the
|
|
shell or shell script being executed as passed in the environment
|
|
or argument list.
|
|
Subsequently, expands to the last argument to the previous simple
|
|
command executed in the foreground, after expansion.
|
|
Also set to the full pathname used to invoke each command executed
|
|
and placed in the environment exported to that command.
|
|
When checking mail, this parameter holds the name of the mail file
|
|
currently being checked.
|
|
<DT><B>BASH</B>
|
|
|
|
<DD>
|
|
Expands to the full filename used to invoke this instance of
|
|
<B>bash</B>.
|
|
|
|
<DT><B>BASHOPTS</B>
|
|
|
|
<DD>
|
|
A colon-separated list of enabled shell options. Each word in
|
|
the list is a valid argument for the
|
|
<B>-s</B>
|
|
|
|
option to the
|
|
<B>shopt</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below). The options appearing in
|
|
<FONT SIZE=-1><B>BASHOPTS</B>
|
|
|
|
</FONT>
|
|
are those reported as
|
|
<I>on</I>
|
|
|
|
by <B>shopt</B>.
|
|
If this variable is in the environment when
|
|
<B>bash</B>
|
|
|
|
starts up, each shell option in the list will be enabled before
|
|
reading any startup files.
|
|
This variable is read-only.
|
|
<DT><B>BASHPID</B>
|
|
|
|
<DD>
|
|
Expands to the process ID of the current <B>bash</B> process.
|
|
This differs from <B>$$</B> under certain circumstances, such as subshells
|
|
that do not require <B>bash</B> to be re-initialized.
|
|
Assignments to
|
|
<FONT SIZE=-1><B>BASHPID</B>
|
|
|
|
</FONT>
|
|
have no effect.
|
|
If
|
|
<B>BASHPID</B>
|
|
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>BASH_ALIASES</B>
|
|
|
|
<DD>
|
|
An associative array variable whose members correspond to the internal
|
|
list of aliases as maintained by the <B>alias</B> builtin.
|
|
Elements added to this array appear in the alias list; however,
|
|
unsetting array elements currently does not cause aliases to be removed
|
|
from the alias list.
|
|
If
|
|
<B>BASH_ALIASES</B>
|
|
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>BASH_ARGC</B>
|
|
|
|
<DD>
|
|
An array variable whose values are the number of parameters in each
|
|
frame of the current <B>bash</B> execution call stack.
|
|
The number of
|
|
parameters to the current subroutine (shell function or script executed
|
|
with <B>.</B> or <B>source</B>) is at the top of the stack.
|
|
When a subroutine is executed, the number of parameters passed is pushed onto
|
|
<FONT SIZE=-1><B>BASH_ARGC</B>.
|
|
|
|
</FONT>
|
|
The shell sets
|
|
<FONT SIZE=-1><B>BASH_ARGC</B>
|
|
|
|
</FONT>
|
|
only when in extended debugging mode (see the description of the
|
|
<B>extdebug</B>
|
|
|
|
option to the
|
|
<B>shopt</B>
|
|
|
|
builtin below).
|
|
Setting <B>extdebug</B> after the shell has started to execute a script,
|
|
or referencing this variable when <B>extdebug</B> is not set,
|
|
may result in inconsistent values.
|
|
<DT><B>BASH_ARGV</B>
|
|
|
|
<DD>
|
|
An array variable containing all of the parameters in the current <B>bash</B>
|
|
execution call stack. The final parameter of the last subroutine call
|
|
is at the top of the stack; the first parameter of the initial call is
|
|
at the bottom. When a subroutine is executed, the parameters supplied
|
|
are pushed onto
|
|
<FONT SIZE=-1><B>BASH_ARGV</B>.
|
|
|
|
</FONT>
|
|
The shell sets
|
|
<FONT SIZE=-1><B>BASH_ARGV</B>
|
|
|
|
</FONT>
|
|
only when in extended debugging mode
|
|
(see the description of the
|
|
<B>extdebug</B>
|
|
|
|
option to the
|
|
<B>shopt</B>
|
|
|
|
builtin below).
|
|
Setting <B>extdebug</B> after the shell has started to execute a script,
|
|
or referencing this variable when <B>extdebug</B> is not set,
|
|
may result in inconsistent values.
|
|
<DT><B>BASH_ARGV0</B>
|
|
|
|
<DD>
|
|
When referenced, this variable expands to the name of the shell or shell
|
|
script (identical to
|
|
<B>$0</B>;
|
|
|
|
see the description of special parameter 0 above).
|
|
Assignment to
|
|
<B>BASH_ARGV0</B>
|
|
|
|
causes the value assigned to also be assigned to <B>$0</B>.
|
|
If
|
|
<B>BASH_ARGV0</B>
|
|
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>BASH_CMDS</B>
|
|
|
|
<DD>
|
|
An associative array variable whose members correspond to the internal
|
|
hash table of commands as maintained by the <B>hash</B> builtin.
|
|
Elements added to this array appear in the hash table; however,
|
|
unsetting array elements currently does not cause command names to be removed
|
|
from the hash table.
|
|
If
|
|
<B>BASH_CMDS</B>
|
|
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>BASH_COMMAND</B>
|
|
|
|
<DD>
|
|
The command currently being executed or about to be executed, unless the
|
|
shell is executing a command as the result of a trap,
|
|
in which case it is the command executing at the time of the trap.
|
|
If
|
|
<B>BASH_COMMAND</B>
|
|
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>BASH_EXECUTION_STRING</B>
|
|
|
|
<DD>
|
|
The command argument to the <B>-c</B> invocation option.
|
|
<DT><B>BASH_LINENO</B>
|
|
|
|
<DD>
|
|
An array variable whose members are the line numbers in source files
|
|
where each corresponding member of
|
|
<FONT SIZE=-1><B>FUNCNAME</B>
|
|
|
|
</FONT>
|
|
was invoked.
|
|
<B>${BASH_LINENO[</B><I>$i</I><B>]}</B> is the line number in the source
|
|
file (<B>${BASH_SOURCE[</B><I>$i+1</I><B>]}</B>) where
|
|
<B>${FUNCNAME[</B><I>$i</I><B>]}</B> was called
|
|
(or <B>${BASH_LINENO[</B><I>$i-1</I><B>]}</B> if referenced within another
|
|
shell function).
|
|
Use
|
|
<FONT SIZE=-1><B>LINENO</B>
|
|
|
|
</FONT>
|
|
to obtain the current line number.
|
|
<DT><B>BASH_LOADABLES_PATH</B>
|
|
|
|
<DD>
|
|
A colon-separated list of directories in which the shell looks for
|
|
dynamically loadable builtins specified by the
|
|
<B>enable</B>
|
|
|
|
command.
|
|
<DT><B>BASH_REMATCH</B>
|
|
|
|
<DD>
|
|
An array variable whose members are assigned by the <B>=~</B> binary
|
|
operator to the <B>[[</B> conditional command.
|
|
The element with index 0 is the portion of the string
|
|
matching the entire regular expression.
|
|
The element with index <I>n</I> is the portion of the
|
|
string matching the <I>n</I>th parenthesized subexpression.
|
|
<DT><B>BASH_SOURCE</B>
|
|
|
|
<DD>
|
|
An array variable whose members are the source filenames
|
|
where the corresponding shell function names in the
|
|
<FONT SIZE=-1><B>FUNCNAME</B>
|
|
|
|
</FONT>
|
|
array variable are defined.
|
|
The shell function
|
|
<B>${FUNCNAME[</B><I>$i</I><B>]}</B> is defined in the file
|
|
<B>${BASH_SOURCE[</B><I>$i</I><B>]}</B> and called from
|
|
<B>${BASH_SOURCE[</B><I>$i+1</I><B>]}</B>.
|
|
<DT><B>BASH_SUBSHELL</B>
|
|
|
|
<DD>
|
|
Incremented by one within each subshell or subshell environment when
|
|
the shell begins executing in that environment.
|
|
The initial value is 0.
|
|
If
|
|
<B>BASH_SUBSHELL</B>
|
|
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>BASH_VERSINFO</B>
|
|
|
|
<DD>
|
|
A readonly array variable whose members hold version information for
|
|
this instance of
|
|
<B>bash</B>.
|
|
|
|
The values assigned to the array members are as follows:
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>BASH_VERSINFO[</B>0]
|
|
|
|
<DD>
|
|
The major version number (the <I>release</I>).
|
|
<DT><B>BASH_VERSINFO[</B>1]
|
|
|
|
<DD>
|
|
The minor version number (the <I>version</I>).
|
|
<DT><B>BASH_VERSINFO[</B>2]
|
|
|
|
<DD>
|
|
The patch level.
|
|
<DT><B>BASH_VERSINFO[</B>3]
|
|
|
|
<DD>
|
|
The build version.
|
|
<DT><B>BASH_VERSINFO[</B>4]
|
|
|
|
<DD>
|
|
The release status (e.g., <I>beta1</I>).
|
|
<DT><B>BASH_VERSINFO[</B>5]
|
|
|
|
<DD>
|
|
The value of
|
|
<FONT SIZE=-1><B>MACHTYPE</B>.
|
|
|
|
</FONT>
|
|
</DL></DL>
|
|
|
|
<DT><B>BASH_VERSION</B>
|
|
|
|
<DD>
|
|
Expands to a string describing the version of this instance of
|
|
<B>bash</B>.
|
|
|
|
<DT><B>COMP_CWORD</B>
|
|
|
|
<DD>
|
|
An index into <B>${COMP_WORDS}</B> of the word containing the current
|
|
cursor position.
|
|
This variable is available only in shell functions invoked by the
|
|
programmable completion facilities (see <B>Programmable Completion</B>
|
|
below).
|
|
<DT><B>COMP_KEY</B>
|
|
|
|
<DD>
|
|
The key (or final key of a key sequence) used to invoke the current
|
|
completion function.
|
|
<DT><B>COMP_LINE</B>
|
|
|
|
<DD>
|
|
The current command line.
|
|
This variable is available only in shell functions and external
|
|
commands invoked by the
|
|
programmable completion facilities (see <B>Programmable Completion</B>
|
|
below).
|
|
<DT><B>COMP_POINT</B>
|
|
|
|
<DD>
|
|
The index of the current cursor position relative to the beginning of
|
|
the current command.
|
|
If the current cursor position is at the end of the current command,
|
|
the value of this variable is equal to <B>${#COMP_LINE}</B>.
|
|
This variable is available only in shell functions and external
|
|
commands invoked by the
|
|
programmable completion facilities (see <B>Programmable Completion</B>
|
|
below).
|
|
<DT><B>COMP_TYPE</B>
|
|
|
|
<DD>
|
|
Set to an integer value corresponding to the type of completion attempted
|
|
that caused a completion function to be called:
|
|
<I>TAB</I>, for normal completion,
|
|
<I>?</I>, for listing completions after successive tabs,
|
|
<I>!</I>, for listing alternatives on partial word completion,
|
|
<I>@</I>, to list completions if the word is not unmodified,
|
|
or
|
|
<I>%</I>, for menu completion.
|
|
This variable is available only in shell functions and external
|
|
commands invoked by the
|
|
programmable completion facilities (see <B>Programmable Completion</B>
|
|
below).
|
|
<DT><B>COMP_WORDBREAKS</B>
|
|
|
|
<DD>
|
|
The set of characters that the <B>readline</B> library treats as word
|
|
separators when performing word completion.
|
|
If
|
|
<FONT SIZE=-1><B>COMP_WORDBREAKS</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>COMP_WORDS</B>
|
|
|
|
<DD>
|
|
An array variable (see <B>Arrays</B> below) consisting of the individual
|
|
words in the current command line.
|
|
The line is split into words as <B>readline</B> would split it, using
|
|
<FONT SIZE=-1><B>COMP_WORDBREAKS</B>
|
|
|
|
</FONT>
|
|
as described above.
|
|
This variable is available only in shell functions invoked by the
|
|
programmable completion facilities (see <B>Programmable Completion</B>
|
|
below).
|
|
<DT><B>COPROC</B>
|
|
|
|
<DD>
|
|
An array variable (see <B>Arrays</B> below) created to hold the file descriptors
|
|
for output from and input to an unnamed coprocess (see <B>Coprocesses</B>
|
|
above).
|
|
<DT><B>DIRSTACK</B>
|
|
|
|
<DD>
|
|
An array variable (see
|
|
<B>Arrays</B>
|
|
|
|
below) containing the current contents of the directory stack.
|
|
Directories appear in the stack in the order they are displayed by the
|
|
<B>dirs</B>
|
|
|
|
builtin.
|
|
Assigning to members of this array variable may be used to modify
|
|
directories already in the stack, but the
|
|
<B>pushd</B>
|
|
|
|
and
|
|
<B>popd</B>
|
|
|
|
builtins must be used to add and remove directories.
|
|
Assignment to this variable will not change the current directory.
|
|
If
|
|
<FONT SIZE=-1><B>DIRSTACK</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>EPOCHREALTIME</B>
|
|
|
|
<DD>
|
|
Each time this parameter is referenced, it expands to the number of seconds
|
|
since the Unix Epoch (see <I>time</I>(3)) as a floating point value
|
|
with micro-second granularity.
|
|
Assignments to
|
|
<FONT SIZE=-1><B>EPOCHREALTIME</B>
|
|
|
|
</FONT>
|
|
are ignored.
|
|
If
|
|
<FONT SIZE=-1><B>EPOCHREALTIME</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>EPOCHSECONDS</B>
|
|
|
|
<DD>
|
|
Each time this parameter is referenced, it expands to the number of seconds
|
|
since the Unix Epoch (see <I>time</I>(3)).
|
|
Assignments to
|
|
<FONT SIZE=-1><B>EPOCHSECONDS</B>
|
|
|
|
</FONT>
|
|
are ignored.
|
|
If
|
|
<FONT SIZE=-1><B>EPOCHSECONDS</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>EUID</B>
|
|
|
|
<DD>
|
|
Expands to the effective user ID of the current user, initialized at
|
|
shell startup. This variable is readonly.
|
|
<DT><B>FUNCNAME</B>
|
|
|
|
<DD>
|
|
An array variable containing the names of all shell functions
|
|
currently in the execution call stack.
|
|
The element with index 0 is the name of any currently-executing
|
|
shell function.
|
|
The bottom-most element (the one with the highest index) is
|
|
<TT>"main"</TT>.
|
|
|
|
This variable exists only when a shell function is executing.
|
|
Assignments to
|
|
<FONT SIZE=-1><B>FUNCNAME</B>
|
|
|
|
</FONT>
|
|
have no effect.
|
|
If
|
|
<FONT SIZE=-1><B>FUNCNAME</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<P>
|
|
|
|
|
|
This variable can be used with <B>BASH_LINENO</B> and <B>BASH_SOURCE</B>.
|
|
Each element of <B>FUNCNAME</B> has corresponding elements in
|
|
<B>BASH_LINENO</B> and <B>BASH_SOURCE</B> to describe the call stack.
|
|
For instance, <B>${FUNCNAME[</B><I>$i</I><B>]}</B> was called from the file
|
|
<B>${BASH_SOURCE[</B><I>$i+1</I><B>]}</B> at line number
|
|
<B>${BASH_LINENO[</B><I>$i</I><B>]}</B>.
|
|
The <B>caller</B> builtin displays the current call stack using this
|
|
information.
|
|
<DT><B>GROUPS</B>
|
|
|
|
<DD>
|
|
An array variable containing the list of groups of which the current
|
|
user is a member.
|
|
Assignments to
|
|
<FONT SIZE=-1><B>GROUPS</B>
|
|
|
|
</FONT>
|
|
have no effect.
|
|
If
|
|
<FONT SIZE=-1><B>GROUPS</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>HISTCMD</B>
|
|
|
|
<DD>
|
|
The history number, or index in the history list, of the current
|
|
command.
|
|
Assignments to
|
|
<FONT SIZE=-1><B>HISTCMD</B>
|
|
|
|
</FONT>
|
|
are ignored.
|
|
If
|
|
<FONT SIZE=-1><B>HISTCMD</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>HOSTNAME</B>
|
|
|
|
<DD>
|
|
Automatically set to the name of the current host.
|
|
<DT><B>HOSTTYPE</B>
|
|
|
|
<DD>
|
|
Automatically set to a string that uniquely
|
|
describes the type of machine on which
|
|
<B>bash</B>
|
|
|
|
is executing.
|
|
The default is system-dependent.
|
|
<DT><B>LINENO</B>
|
|
|
|
<DD>
|
|
Each time this parameter is referenced, the shell substitutes
|
|
a decimal number representing the current sequential line number
|
|
(starting with 1) within a script or function. When not in a
|
|
script or function, the value substituted is not guaranteed to
|
|
be meaningful.
|
|
If
|
|
<FONT SIZE=-1><B>LINENO</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>MACHTYPE</B>
|
|
|
|
<DD>
|
|
Automatically set to a string that fully describes the system
|
|
type on which
|
|
<B>bash</B>
|
|
|
|
is executing, in the standard GNU <I>cpu-company-system</I> format.
|
|
The default is system-dependent.
|
|
<DT><B>MAPFILE</B>
|
|
|
|
<DD>
|
|
An array variable (see <B>Arrays</B> below) created to hold the text
|
|
read by the <B>mapfile</B> builtin when no variable name is supplied.
|
|
<DT><B>OLDPWD</B>
|
|
|
|
<DD>
|
|
The previous working directory as set by the
|
|
<B>cd</B>
|
|
|
|
command.
|
|
<DT><B>OPTARG</B>
|
|
|
|
<DD>
|
|
The value of the last option argument processed by the
|
|
<B>getopts</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<DT><B>OPTIND</B>
|
|
|
|
<DD>
|
|
The index of the next argument to be processed by the
|
|
<B>getopts</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<DT><B>OSTYPE</B>
|
|
|
|
<DD>
|
|
Automatically set to a string that
|
|
describes the operating system on which
|
|
<B>bash</B>
|
|
|
|
is executing.
|
|
The default is system-dependent.
|
|
<DT><B>PIPESTATUS</B>
|
|
|
|
<DD>
|
|
An array variable (see
|
|
<B>Arrays</B>
|
|
|
|
below) containing a list of exit status values from the processes
|
|
in the most-recently-executed foreground pipeline (which may
|
|
contain only a single command).
|
|
<DT><B>PPID</B>
|
|
|
|
<DD>
|
|
The process ID of the shell's parent. This variable is readonly.
|
|
<DT><B>PWD</B>
|
|
|
|
<DD>
|
|
The current working directory as set by the
|
|
<B>cd</B>
|
|
|
|
command.
|
|
<DT><B>RANDOM</B>
|
|
|
|
<DD>
|
|
Each time this parameter is referenced, it expands to a random integer
|
|
between 0 and 32767.
|
|
Assigning
|
|
a value to
|
|
<FONT SIZE=-1><B>RANDOM</B>
|
|
|
|
</FONT>
|
|
initializes (seeds) the sequence of random numbers.
|
|
If
|
|
<FONT SIZE=-1><B>RANDOM</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>READLINE_ARGUMENT</B>
|
|
|
|
<DD>
|
|
Any numeric argument given to a readline command that was defined using
|
|
<TT>bind -x</TT>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below)
|
|
when it was invoked.
|
|
<DT><B>READLINE_LINE</B>
|
|
|
|
<DD>
|
|
The contents of the
|
|
<B>readline</B>
|
|
|
|
line buffer, for use with
|
|
<TT>bind -x</TT>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<DT><B>READLINE_MARK</B>
|
|
|
|
<DD>
|
|
The position of the mark (saved insertion point) in the
|
|
<B>readline</B>
|
|
|
|
line buffer, for use with
|
|
<TT>bind -x</TT>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
The characters between the insertion point and the mark are often
|
|
called the <I>region</I>.
|
|
<DT><B>READLINE_POINT</B>
|
|
|
|
<DD>
|
|
The position of the insertion point in the
|
|
<B>readline</B>
|
|
|
|
line buffer, for use with
|
|
<TT>bind -x</TT>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<DT><B>REPLY</B>
|
|
|
|
<DD>
|
|
Set to the line of input read by the
|
|
<B>read</B>
|
|
|
|
builtin command when no arguments are supplied.
|
|
<DT><B>SECONDS</B>
|
|
|
|
<DD>
|
|
Each time this parameter is
|
|
referenced, it expands to the number of seconds since shell invocation.
|
|
If a value is assigned to
|
|
<FONT SIZE=-1><B>SECONDS</B>,
|
|
|
|
</FONT>
|
|
the value returned upon subsequent
|
|
references is
|
|
the number of seconds since the assignment plus the value assigned.
|
|
The number of seconds at shell invocation and the current time are always
|
|
determined by querying the system clock.
|
|
If
|
|
<FONT SIZE=-1><B>SECONDS</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties, even if it is
|
|
subsequently reset.
|
|
<DT><B>SHELLOPTS</B>
|
|
|
|
<DD>
|
|
A colon-separated list of enabled shell options. Each word in
|
|
the list is a valid argument for the
|
|
<B>-o</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below). The options appearing in
|
|
<FONT SIZE=-1><B>SHELLOPTS</B>
|
|
|
|
</FONT>
|
|
are those reported as
|
|
<I>on</I>
|
|
|
|
by <B>set -o</B>.
|
|
If this variable is in the environment when
|
|
<B>bash</B>
|
|
|
|
starts up, each shell option in the list will be enabled before
|
|
reading any startup files.
|
|
This variable is read-only.
|
|
<DT><B>SHLVL</B>
|
|
|
|
<DD>
|
|
Incremented by one each time an instance of
|
|
<B>bash</B>
|
|
|
|
is started.
|
|
<DT><B>SRANDOM</B>
|
|
|
|
<DD>
|
|
This variable expands to a 32-bit pseudo-random number each time it is
|
|
referenced. The random number generator is not linear on systems that
|
|
support <TT>/dev/urandom</TT> or <I>arc4random</I>, so each returned number
|
|
has no relationship to the numbers preceding it.
|
|
The random number generator cannot be seeded, so assignments to this
|
|
variable have no effect.
|
|
If
|
|
<FONT SIZE=-1><B>SRANDOM</B>
|
|
|
|
</FONT>
|
|
is unset, it loses its special properties,
|
|
even if it is subsequently reset.
|
|
<DT><B>UID</B>
|
|
|
|
<DD>
|
|
Expands to the user ID of the current user, initialized at shell startup.
|
|
This variable is readonly.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The following variables are used by the shell. In some cases,
|
|
<B>bash</B>
|
|
|
|
assigns a default value to a variable; these cases are noted
|
|
below.
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>BASH_COMPAT</B>
|
|
|
|
<DD>
|
|
The value is used to set the shell's compatibility level.
|
|
See
|
|
<FONT SIZE=-1><B>SHELL COMPATIBILITY MODE</B>
|
|
|
|
</FONT>
|
|
below for a description of the various compatibility
|
|
levels and their effects.
|
|
The value may be a decimal number (e.g., 4.2) or an integer (e.g., 42)
|
|
corresponding to the desired compatibility level.
|
|
If <B>BASH_COMPAT</B> is unset or set to the empty string, the compatibility
|
|
level is set to the default for the current version.
|
|
If <B>BASH_COMPAT</B> is set to a value that is not one of the valid
|
|
compatibility levels, the shell prints an error message and sets the
|
|
compatibility level to the default for the current version.
|
|
The valid values correspond to the compatibility levels
|
|
described below under
|
|
<FONT SIZE=-1><B>SHELL COMPATIBILITY MODE</B>.
|
|
|
|
</FONT>
|
|
For example, 4.2 and 42 are valid values that correspond
|
|
to the <B>compat42</B> <B>shopt</B> option
|
|
and set the compatibility level to 42.
|
|
The current version is also a valid value.
|
|
<DT><B>BASH_ENV</B>
|
|
|
|
<DD>
|
|
If this parameter is set when <B>bash</B> is executing a shell script,
|
|
its value is interpreted as a filename containing commands to
|
|
initialize the shell, as in
|
|
<A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>.
|
|
|
|
The value of
|
|
<FONT SIZE=-1><B>BASH_ENV</B>
|
|
|
|
</FONT>
|
|
is subjected to parameter expansion, command substitution, and arithmetic
|
|
expansion before being interpreted as a filename.
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
is not used to search for the resultant filename.
|
|
<DT><B>BASH_XTRACEFD</B>
|
|
|
|
<DD>
|
|
If set to an integer corresponding to a valid file descriptor, <B>bash</B>
|
|
will write the trace output generated when
|
|
<TT>set -x</TT>
|
|
|
|
is enabled to that file descriptor.
|
|
The file descriptor is closed when
|
|
<FONT SIZE=-1><B>BASH_XTRACEFD</B>
|
|
|
|
</FONT>
|
|
is unset or assigned a new value.
|
|
Unsetting
|
|
<FONT SIZE=-1><B>BASH_XTRACEFD</B>
|
|
|
|
</FONT>
|
|
or assigning it the empty string causes the
|
|
trace output to be sent to the standard error.
|
|
Note that setting
|
|
<FONT SIZE=-1><B>BASH_XTRACEFD</B>
|
|
|
|
</FONT>
|
|
to 2 (the standard error file
|
|
descriptor) and then unsetting it will result in the standard error
|
|
being closed.
|
|
<DT><B>CDPATH</B>
|
|
|
|
<DD>
|
|
The search path for the
|
|
<B>cd</B>
|
|
|
|
command.
|
|
This is a colon-separated list of directories in which the shell looks
|
|
for destination directories specified by the
|
|
<B>cd</B>
|
|
|
|
command.
|
|
A sample value is
|
|
<TT>".:~:/usr"</TT>.
|
|
|
|
<DT><B>CHILD_MAX</B>
|
|
|
|
<DD>
|
|
Set the number of exited child status values for the shell to remember.
|
|
Bash will not allow this value to be decreased below a POSIX-mandated
|
|
minimum, and there is a maximum value (currently 8192) that this may
|
|
not exceed.
|
|
The minimum value is system-dependent.
|
|
<DT><B>COLUMNS</B>
|
|
|
|
<DD>
|
|
Used by the <B>select</B> compound command to determine the terminal width
|
|
when printing selection lists.
|
|
Automatically set if the
|
|
<B>checkwinsize</B>
|
|
|
|
option is enabled or in an interactive shell upon receipt of a
|
|
<FONT SIZE=-1><B>SIGWINCH</B>.
|
|
|
|
</FONT>
|
|
<DT><B>COMPREPLY</B>
|
|
|
|
<DD>
|
|
An array variable from which <B>bash</B> reads the possible completions
|
|
generated by a shell function invoked by the programmable completion
|
|
facility (see <B>Programmable Completion</B> below).
|
|
Each array element contains one possible completion.
|
|
<DT><B>EMACS</B>
|
|
|
|
<DD>
|
|
If <B>bash</B> finds this variable in the environment when the shell starts
|
|
with value
|
|
<TT>t</TT>,
|
|
|
|
it assumes that the shell is running in an Emacs shell buffer and disables
|
|
line editing.
|
|
<DT><B>ENV</B>
|
|
|
|
<DD>
|
|
Expanded and executed similarly to
|
|
<FONT SIZE=-1><B>BASH_ENV</B>
|
|
|
|
</FONT>
|
|
(see <B>INVOCATION</B> above)
|
|
when an interactive shell is invoked in <I>posix mode</I>.
|
|
<DT><B>EXECIGNORE</B>
|
|
|
|
<DD>
|
|
A colon-separated list of shell patterns (see <B>Pattern Matching</B>)
|
|
defining the list of filenames to be ignored by command search using
|
|
<B>PATH</B>.
|
|
Files whose full pathnames match one of these patterns are not considered
|
|
executable files for the purposes of completion and command execution
|
|
via <B>PATH</B> lookup.
|
|
This does not affect the behavior of the <B>[</B>, <B>test</B>, and <B>[[</B>
|
|
commands.
|
|
Full pathnames in the command hash table are not subject to <B>EXECIGNORE</B>.
|
|
Use this variable to ignore shared library files that have the executable
|
|
bit set, but are not executable files.
|
|
The pattern matching honors the setting of the <B>extglob</B> shell
|
|
option.
|
|
<DT><B>FCEDIT</B>
|
|
|
|
<DD>
|
|
The default editor for the
|
|
<B>fc</B>
|
|
|
|
builtin command.
|
|
<DT><B>FIGNORE</B>
|
|
|
|
<DD>
|
|
A colon-separated list of suffixes to ignore when performing
|
|
filename completion (see
|
|
<FONT SIZE=-1><B>READLINE</B>
|
|
|
|
</FONT>
|
|
below).
|
|
A filename whose suffix matches one of the entries in
|
|
<FONT SIZE=-1><B>FIGNORE</B>
|
|
|
|
</FONT>
|
|
is excluded from the list of matched filenames.
|
|
A sample value is
|
|
<TT>".o:~"</TT>.
|
|
|
|
<DT><B>FUNCNEST</B>
|
|
|
|
<DD>
|
|
If set to a numeric value greater than 0, defines a maximum function
|
|
nesting level. Function invocations that exceed this nesting level
|
|
will cause the current command to abort.
|
|
<DT><B>GLOBIGNORE</B>
|
|
|
|
<DD>
|
|
A colon-separated list of patterns defining the set of file names to
|
|
be ignored by pathname expansion.
|
|
If a file name matched by a pathname expansion pattern also matches one
|
|
of the patterns in
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>,
|
|
|
|
</FONT>
|
|
it is removed from the list of matches.
|
|
<DT><B>HISTCONTROL</B>
|
|
|
|
<DD>
|
|
A colon-separated list of values controlling how commands are saved on
|
|
the history list.
|
|
If the list of values includes
|
|
<I>ignorespace</I>,
|
|
|
|
lines which begin with a
|
|
<B>space</B>
|
|
|
|
character are not saved in the history list.
|
|
A value of
|
|
<I>ignoredups</I>
|
|
|
|
causes lines matching the previous history entry to not be saved.
|
|
A value of
|
|
<I>ignoreboth</I>
|
|
|
|
is shorthand for <I>ignorespace</I> and <I>ignoredups</I>.
|
|
A value of
|
|
<I>erasedups</I>
|
|
|
|
causes all previous lines matching the current line to be removed from
|
|
the history list before that line is saved.
|
|
Any value not in the above list is ignored.
|
|
If
|
|
<FONT SIZE=-1><B>HISTCONTROL</B>
|
|
|
|
</FONT>
|
|
is unset, or does not include a valid value,
|
|
all lines read by the shell parser are saved on the history list,
|
|
subject to the value of
|
|
<FONT SIZE=-1><B>HISTIGNORE</B>.
|
|
|
|
</FONT>
|
|
The second and subsequent lines of a multi-line compound command are
|
|
not tested, and are added to the history regardless of the value of
|
|
<FONT SIZE=-1><B>HISTCONTROL</B>.
|
|
|
|
</FONT>
|
|
<DT><B>HISTFILE</B>
|
|
|
|
<DD>
|
|
The name of the file in which command history is saved (see
|
|
<FONT SIZE=-1><B>HISTORY</B>
|
|
|
|
</FONT>
|
|
below). The default value is <A HREF="file:~/.bash_history"><I>~/.bash_history</I></A>. If unset, the
|
|
command history is not saved when a shell exits.
|
|
<DT><B>HISTFILESIZE</B>
|
|
|
|
<DD>
|
|
The maximum number of lines contained in the history file. When this
|
|
variable is assigned a value, the history file is truncated, if
|
|
necessary,
|
|
to contain no more than that number of lines by removing the oldest entries.
|
|
The history file is also truncated to this size after
|
|
writing it when a shell exits.
|
|
If the value is 0, the history file is truncated to zero size.
|
|
Non-numeric values and numeric values less than zero inhibit truncation.
|
|
The shell sets the default value to the value of <B>HISTSIZE</B>
|
|
after reading any startup files.
|
|
<DT><B>HISTIGNORE</B>
|
|
|
|
<DD>
|
|
A colon-separated list of patterns used to decide which command lines
|
|
should be saved on the history list. Each pattern is anchored at the
|
|
beginning of the line and must match the complete line (no implicit
|
|
`<B>*</B>' is appended). Each pattern is tested against the line
|
|
after the checks specified by
|
|
<FONT SIZE=-1><B>HISTCONTROL</B>
|
|
|
|
</FONT>
|
|
are applied.
|
|
In addition to the normal shell pattern matching characters, `<B>&</B>'
|
|
matches the previous history line. `<B>&</B>' may be escaped using a
|
|
backslash; the backslash is removed before attempting a match.
|
|
The second and subsequent lines of a multi-line compound command are
|
|
not tested, and are added to the history regardless of the value of
|
|
<FONT SIZE=-1><B>HISTIGNORE</B>.
|
|
|
|
</FONT>
|
|
The pattern matching honors the setting of the <B>extglob</B> shell
|
|
option.
|
|
<DT><B>HISTSIZE</B>
|
|
|
|
<DD>
|
|
The number of commands to remember in the command history (see
|
|
<FONT SIZE=-1><B>HISTORY</B>
|
|
|
|
</FONT>
|
|
below).
|
|
If the value is 0, commands are not saved in the history list.
|
|
Numeric values less than zero result in every command being saved
|
|
on the history list (there is no limit).
|
|
The shell sets the default value to 500 after reading any startup files.
|
|
<DT><B>HISTTIMEFORMAT</B>
|
|
|
|
<DD>
|
|
If this variable is set and not null, its value is used as a format string
|
|
for <I>strftime</I>(3) to print the time stamp associated with each history
|
|
entry displayed by the <B>history</B> builtin.
|
|
If this variable is set, time stamps are written to the history file so
|
|
they may be preserved across shell sessions.
|
|
This uses the history comment character to distinguish timestamps from
|
|
other history lines.
|
|
<DT><B>HOME</B>
|
|
|
|
<DD>
|
|
The home directory of the current user; the default argument for the
|
|
<B>cd</B> builtin command.
|
|
The value of this variable is also used when performing tilde expansion.
|
|
<DT><B>HOSTFILE</B>
|
|
|
|
<DD>
|
|
Contains the name of a file in the same format as
|
|
|
|
<I>/etc/hosts</I>
|
|
|
|
that should be read when the shell needs to complete a
|
|
hostname.
|
|
The list of possible hostname completions may be changed while the
|
|
shell is running;
|
|
the next time hostname completion is attempted after the
|
|
value is changed,
|
|
<B>bash</B>
|
|
|
|
adds the contents of the new file to the existing list.
|
|
If
|
|
<FONT SIZE=-1><B>HOSTFILE</B>
|
|
|
|
</FONT>
|
|
is set, but has no value, or does not name a readable file,
|
|
<B>bash</B> attempts to read
|
|
|
|
<I>/etc/hosts</I>
|
|
|
|
to obtain the list of possible hostname completions.
|
|
When
|
|
<FONT SIZE=-1><B>HOSTFILE</B>
|
|
|
|
</FONT>
|
|
is unset, the hostname list is cleared.
|
|
<DT><B>IFS</B>
|
|
|
|
<DD>
|
|
The
|
|
<I>Internal Field Separator</I>
|
|
|
|
that is used
|
|
for word splitting after expansion and to
|
|
split lines into words with the
|
|
<B>read</B>
|
|
|
|
builtin command. The default value is
|
|
``<space><tab><newline>''.
|
|
<DT><B>IGNOREEOF</B>
|
|
|
|
<DD>
|
|
Controls the
|
|
action of an interactive shell on receipt of an
|
|
<FONT SIZE=-1><B>EOF</B>
|
|
|
|
</FONT>
|
|
character as the sole input. If set, the value is the number of
|
|
consecutive
|
|
<FONT SIZE=-1><B>EOF</B>
|
|
|
|
</FONT>
|
|
characters which must be
|
|
typed as the first characters on an input line before
|
|
<B>bash</B>
|
|
|
|
exits. If the variable exists but does not have a numeric value, or
|
|
has no value, the default value is 10. If it does not exist,
|
|
<FONT SIZE=-1><B>EOF</B>
|
|
|
|
</FONT>
|
|
signifies the end of input to the shell.
|
|
<DT><B>INPUTRC</B>
|
|
|
|
<DD>
|
|
The filename for the
|
|
<B>readline</B>
|
|
|
|
startup file, overriding the default of
|
|
|
|
<A HREF="file:~/.inputrc"><I>~/.inputrc</I></A>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>READLINE</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<DT><B>INSIDE_EMACS</B>
|
|
|
|
<DD>
|
|
If this variable appears in the environment when the shell starts,
|
|
<B>bash</B> assumes that it is running inside an Emacs shell buffer
|
|
and may disable line editing, depending on the value of <B>TERM</B>.
|
|
<DT><B>LANG</B>
|
|
|
|
<DD>
|
|
Used to determine the locale category for any category not specifically
|
|
selected with a variable starting with <B>LC_</B>.
|
|
<DT><B>LC_ALL</B>
|
|
|
|
<DD>
|
|
This variable overrides the value of
|
|
<FONT SIZE=-1><B>LANG</B>
|
|
|
|
</FONT>
|
|
and any other
|
|
<B>LC_</B> variable specifying a locale category.
|
|
<DT><B>LC_COLLATE</B>
|
|
|
|
<DD>
|
|
This variable determines the collation order used when sorting the
|
|
results of pathname expansion, and determines the behavior of range
|
|
expressions, equivalence classes, and collating sequences within
|
|
pathname expansion and pattern matching.
|
|
<DT><B>LC_CTYPE</B>
|
|
|
|
<DD>
|
|
This variable determines the interpretation of characters and the
|
|
behavior of character classes within pathname expansion and pattern
|
|
matching.
|
|
<DT><B>LC_MESSAGES</B>
|
|
|
|
<DD>
|
|
This variable determines the locale used to translate double-quoted
|
|
strings preceded by a <B>$</B>.
|
|
<DT><B>LC_NUMERIC</B>
|
|
|
|
<DD>
|
|
This variable determines the locale category used for number formatting.
|
|
<DT><B>LC_TIME</B>
|
|
|
|
<DD>
|
|
This variable determines the locale category used for data and time
|
|
formatting.
|
|
<DT><B>LINES</B>
|
|
|
|
<DD>
|
|
Used by the <B>select</B> compound command to determine the column length
|
|
for printing selection lists.
|
|
Automatically set if the
|
|
<B>checkwinsize</B>
|
|
|
|
option is enabled or in an interactive shell upon receipt of a
|
|
<FONT SIZE=-1><B>SIGWINCH</B>.
|
|
|
|
</FONT>
|
|
<DT><B>MAIL</B>
|
|
|
|
<DD>
|
|
If this parameter is set to a file or directory name and the
|
|
<FONT SIZE=-1><B>MAILPATH</B>
|
|
|
|
</FONT>
|
|
variable is not set,
|
|
<B>bash</B>
|
|
|
|
informs the user of the arrival of mail in the specified file or
|
|
Maildir-format directory.
|
|
<DT><B>MAILCHECK</B>
|
|
|
|
<DD>
|
|
Specifies how
|
|
often (in seconds)
|
|
<B>bash</B>
|
|
|
|
checks for mail. The default is 60 seconds. When it is time to check
|
|
for mail, the shell does so before displaying the primary prompt.
|
|
If this variable is unset, or set to a value that is not a number
|
|
greater than or equal to zero, the shell disables mail checking.
|
|
<DT><B>MAILPATH</B>
|
|
|
|
<DD>
|
|
A colon-separated list of filenames to be checked for mail.
|
|
The message to be printed when mail arrives in a particular file
|
|
may be specified by separating the filename from the message with a `?'.
|
|
When used in the text of the message, <B>$_</B> expands to the name of
|
|
the current mailfile.
|
|
Example:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>MAILPATH</B>=aq/var/mail/bfox?"You have mail":~/shell-mail?"$_ has mail!"aq
|
|
<P>
|
|
|
|
<B>Bash</B>
|
|
|
|
can be configured to supply
|
|
a default value for this variable (there is no value by default),
|
|
but the location of the user
|
|
mail files that it uses is system dependent (e.g., /var/mail/<B>$USER</B>).
|
|
</DL>
|
|
|
|
<DT><B>OPTERR</B>
|
|
|
|
<DD>
|
|
If set to the value 1,
|
|
<B>bash</B>
|
|
|
|
displays error messages generated by the
|
|
<B>getopts</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<FONT SIZE=-1><B>OPTERR</B>
|
|
|
|
</FONT>
|
|
is initialized to 1 each time the shell is invoked or a shell
|
|
script is executed.
|
|
<DT><B>PATH</B>
|
|
|
|
<DD>
|
|
The search path for commands. It
|
|
is a colon-separated list of directories in which
|
|
the shell looks for commands (see
|
|
<FONT SIZE=-1><B>COMMAND EXECUTION</B>
|
|
|
|
</FONT>
|
|
below).
|
|
A zero-length (null) directory name in the value of
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
indicates the current directory.
|
|
A null directory name may appear as two adjacent colons, or as an initial
|
|
or trailing colon.
|
|
The default path is system-dependent,
|
|
and is set by the administrator who installs
|
|
<B>bash</B>.
|
|
|
|
A common value is
|
|
|
|
<TT>/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin</TT>.
|
|
|
|
|
|
<DT><B>POSIXLY_CORRECT</B>
|
|
|
|
<DD>
|
|
If this variable is in the environment when <B>bash</B> starts, the shell
|
|
enters <I>posix mode</I> before reading the startup files, as if the
|
|
<B>--posix</B>
|
|
|
|
invocation option had been supplied. If it is set while the shell is
|
|
running, <B>bash</B> enables <I>posix mode</I>, as if the command
|
|
<TT>set -o posix</TT>
|
|
|
|
had been executed.
|
|
When the shell enters <I>posix mode</I>, it sets this variable if it was
|
|
not already set.
|
|
<DT><B>PROMPT_COMMAND</B>
|
|
|
|
<DD>
|
|
If this variable is set, and is an array,
|
|
the value of each set element is executed as a command
|
|
prior to issuing each primary prompt.
|
|
If this is set but not an array variable,
|
|
its value is used as a command to execute instead.
|
|
<DT><B>PROMPT_DIRTRIM</B>
|
|
|
|
<DD>
|
|
If set to a number greater than zero, the value is used as the number of
|
|
trailing directory components to retain when expanding the <B>\w</B> and
|
|
<B>\W</B> prompt string escapes (see
|
|
<FONT SIZE=-1><B>PROMPTING</B>
|
|
|
|
</FONT>
|
|
below). Characters removed are replaced with an ellipsis.
|
|
<DT><B>PS0</B>
|
|
|
|
<DD>
|
|
The value of this parameter is expanded (see
|
|
<FONT SIZE=-1><B>PROMPTING</B>
|
|
|
|
</FONT>
|
|
below) and displayed by interactive shells after reading a command
|
|
and before the command is executed.
|
|
<DT><B>PS1</B>
|
|
|
|
<DD>
|
|
The value of this parameter is expanded (see
|
|
<FONT SIZE=-1><B>PROMPTING</B>
|
|
|
|
</FONT>
|
|
below) and used as the primary prompt string. The default value is
|
|
``<B>\s-\v\$ </B>''.
|
|
<DT><B>PS2</B>
|
|
|
|
<DD>
|
|
The value of this parameter is expanded as with
|
|
<FONT SIZE=-1><B>PS1</B>
|
|
|
|
</FONT>
|
|
and used as the secondary prompt string. The default is
|
|
``<B>> </B>''.
|
|
<DT><B>PS3</B>
|
|
|
|
<DD>
|
|
The value of this parameter is used as the prompt for the
|
|
<B>select</B>
|
|
|
|
command (see
|
|
<FONT SIZE=-1><B>SHELL GRAMMAR</B>
|
|
|
|
</FONT>
|
|
above).
|
|
<DT><B>PS4</B>
|
|
|
|
<DD>
|
|
The value of this parameter is expanded as with
|
|
<FONT SIZE=-1><B>PS1</B>
|
|
|
|
</FONT>
|
|
and the value is printed before each command
|
|
<B>bash</B>
|
|
|
|
displays during an execution trace. The first character of
|
|
the expanded value of
|
|
<FONT SIZE=-1><B>PS4</B>
|
|
|
|
</FONT>
|
|
is replicated multiple times, as necessary, to indicate multiple
|
|
levels of indirection. The default is ``<B>+ </B>''.
|
|
<DT><B>SHELL</B>
|
|
|
|
<DD>
|
|
This variable expands to the full pathname to the shell.
|
|
If it is not set when the shell starts,
|
|
<B>bash</B>
|
|
|
|
assigns to it the full pathname of the current user's login shell.
|
|
<DT><B>TIMEFORMAT</B>
|
|
|
|
<DD>
|
|
The value of this parameter is used as a format string specifying
|
|
how the timing information for pipelines prefixed with the
|
|
<B>time</B>
|
|
|
|
reserved word should be displayed.
|
|
The <B>%</B> character introduces an escape sequence that is
|
|
expanded to a time value or other information.
|
|
The escape sequences and their meanings are as follows; the
|
|
braces denote optional portions.
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>%%</B>
|
|
|
|
<DD>
|
|
A literal <B>%</B>.
|
|
<DT><B>%[</B><I>p</I>][l]R
|
|
|
|
<DD>
|
|
The elapsed time in seconds.
|
|
<DT><B>%[</B><I>p</I>][l]U
|
|
|
|
<DD>
|
|
The number of CPU seconds spent in user mode.
|
|
<DT><B>%[</B><I>p</I>][l]S
|
|
|
|
<DD>
|
|
The number of CPU seconds spent in system mode.
|
|
<DT><B>%P</B>
|
|
|
|
<DD>
|
|
The CPU percentage, computed as (%U + %S) / %R.
|
|
|
|
</DL></DL>
|
|
|
|
<DT><DD>
|
|
The optional <I>p</I> is a digit specifying the <I>precision</I>,
|
|
the number of fractional digits after a decimal point.
|
|
A value of 0 causes no decimal point or fraction to be output.
|
|
At most three places after the decimal point may be specified;
|
|
values of <I>p</I> greater than 3 are changed to 3.
|
|
If <I>p</I> is not specified, the value 3 is used.
|
|
<DT><DD>
|
|
The optional <B>l</B> specifies a longer format, including
|
|
minutes, of the form <I>MM</I>m<I>SS</I>.<I>FF</I>s.
|
|
The value of <I>p</I> determines whether or not the fraction is
|
|
included.
|
|
<DT><DD>
|
|
If this variable is not set, <B>bash</B> acts as if it had the
|
|
value <B>$aq\nreal\t%3lR\nuser\t%3lU\nsys\t%3lSaq</B>.
|
|
If the value is null, no timing information is displayed.
|
|
A trailing newline is added when the format string is displayed.
|
|
|
|
<DT><B>TMOUT</B>
|
|
|
|
<DD>
|
|
If set to a value greater than zero,
|
|
<FONT SIZE=-1><B>TMOUT</B>
|
|
|
|
</FONT>
|
|
is treated as the
|
|
default timeout for the <B>read</B> builtin.
|
|
The <B>select</B> command terminates if input does not arrive
|
|
after
|
|
<FONT SIZE=-1><B>TMOUT</B>
|
|
|
|
</FONT>
|
|
seconds when input is coming from a terminal.
|
|
In an interactive shell, the value is interpreted as the
|
|
number of seconds to wait for a line of input after issuing the
|
|
primary prompt.
|
|
<B>Bash</B>
|
|
|
|
terminates after waiting for that number of seconds if a complete
|
|
line of input does not arrive.
|
|
<DT><B>TMPDIR</B>
|
|
|
|
<DD>
|
|
If set, <B>bash</B> uses its value as the name of a directory in which
|
|
<B>bash</B> creates temporary files for the shell's use.
|
|
<DT><B>auto_resume</B>
|
|
|
|
<DD>
|
|
This variable controls how the shell interacts with the user and
|
|
job control. If this variable is set, single word simple
|
|
commands without redirections are treated as candidates for resumption
|
|
of an existing stopped job. There is no ambiguity allowed; if there is
|
|
more than one job beginning with the string typed, the job most recently
|
|
accessed is selected. The
|
|
<I>name</I>
|
|
|
|
of a stopped job, in this context, is the command line used to
|
|
start it.
|
|
If set to the value
|
|
<I>exact</I>,
|
|
|
|
the string supplied must match the name of a stopped job exactly;
|
|
if set to
|
|
<I>substring</I>,
|
|
|
|
the string supplied needs to match a substring of the name of a
|
|
stopped job. The
|
|
<I>substring</I>
|
|
|
|
value provides functionality analogous to the
|
|
<B>%?</B>
|
|
|
|
job identifier (see
|
|
<FONT SIZE=-1><B>JOB CONTROL</B>
|
|
|
|
</FONT>
|
|
below). If set to any other value, the supplied string must
|
|
be a prefix of a stopped job's name; this provides functionality
|
|
analogous to the <B>%</B><I>string</I> job identifier.
|
|
<DT><B>histchars</B>
|
|
|
|
<DD>
|
|
The two or three characters which control history expansion
|
|
and tokenization (see
|
|
<FONT SIZE=-1><B>HISTORY EXPANSION</B>
|
|
|
|
</FONT>
|
|
below). The first character is the <I>history expansion</I> character,
|
|
the character which signals the start of a history
|
|
expansion, normally `<B>!</B>'.
|
|
The second character is the <I>quick substitution</I>
|
|
character, which is used as shorthand for re-running the previous
|
|
command entered, substituting one string for another in the command.
|
|
The default is `<B>^</B>'.
|
|
The optional third character is the character
|
|
which indicates that the remainder of the line is a comment when found
|
|
as the first character of a word, normally `<B>#</B>'. The history
|
|
comment character causes history substitution to be skipped for the
|
|
remaining words on the line. It does not necessarily cause the shell
|
|
parser to treat the rest of the line as a comment.
|
|
|
|
</DL>
|
|
<A NAME="lbAX"> </A>
|
|
<H4>Arrays</H4>
|
|
|
|
<B>Bash</B>
|
|
|
|
provides one-dimensional indexed and associative array variables.
|
|
Any variable may be used as an indexed array; the
|
|
<B>declare</B>
|
|
|
|
builtin will explicitly declare an array.
|
|
There is no maximum
|
|
limit on the size of an array, nor any requirement that members
|
|
be indexed or assigned contiguously.
|
|
Indexed arrays are referenced using integers (including arithmetic
|
|
expressions) and are zero-based; associative arrays are referenced
|
|
using arbitrary strings.
|
|
Unless otherwise noted, indexed array indices must be non-negative integers.
|
|
<P>
|
|
|
|
An indexed array is created automatically if any variable is assigned to
|
|
using the syntax <I>name</I>[<I>subscript</I>]=<I>value</I>. The
|
|
<I>subscript</I>
|
|
|
|
is treated as an arithmetic expression that must evaluate to a number.
|
|
To explicitly declare an indexed array, use
|
|
<B>declare -a </B><I>name</I>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<B>declare -a </B><I>name</I>[<I>subscript</I>]
|
|
|
|
is also accepted; the <I>subscript</I> is ignored.
|
|
<P>
|
|
|
|
Associative arrays are created using
|
|
<B>declare -A </B><I>name</I>.
|
|
|
|
<P>
|
|
|
|
Attributes may be
|
|
specified for an array variable using the
|
|
<B>declare</B>
|
|
|
|
and
|
|
<B>readonly</B>
|
|
|
|
builtins. Each attribute applies to all members of an array.
|
|
<P>
|
|
|
|
Arrays are assigned to using compound assignments of the form
|
|
<I>name</I>=<B>(</B>value<I>1</I> ... value<I>n</I><B>)</B>, where each
|
|
<I>value</I> may be of the form [<I>subscript</I>]=<I>string</I>.
|
|
Indexed array assignments do not require anything but <I>string</I>.
|
|
Each <I>value</I> in the list is expanded using all the shell expansions
|
|
described below under
|
|
<FONT SIZE=-1><B>EXPANSION</B>.
|
|
|
|
</FONT>
|
|
When assigning to indexed arrays, if the optional brackets and subscript
|
|
are supplied, that index is assigned to;
|
|
otherwise the index of the element assigned is the last index assigned
|
|
to by the statement plus one. Indexing starts at zero.
|
|
<P>
|
|
|
|
When assigning to an associative array, the words in a compound assignment
|
|
may be either assignment statements, for which the subscript is required,
|
|
or a list of words that is interpreted as a sequence of alternating keys
|
|
and values:
|
|
<I>name</I>=<B>( </B><I>key1 value1 key2 value2</I> ...<B>)</B>.
|
|
These are treated identically to
|
|
<I>name</I>=<B>(</B> [<I>key1</I>]=<I>value1</I> [<I>key2</I>]=<I>value2</I> ...<B>)</B>.
|
|
The first word in the list determines how the remaining words
|
|
are interpreted; all assignments in a list must be of the same type.
|
|
When using key/value pairs, the keys may not be missing or empty;
|
|
a final missing value is treated like the empty string.
|
|
<P>
|
|
|
|
This syntax is also accepted by the
|
|
<B>declare</B>
|
|
|
|
builtin. Individual array elements may be assigned to using the
|
|
<I>name</I>[<I>subscript</I>]=<I>value</I> syntax introduced above.
|
|
When assigning to an indexed array, if
|
|
<I>name</I>
|
|
|
|
is subscripted by a negative number, that number is
|
|
interpreted as relative to one greater than the maximum index of
|
|
<I>name</I>, so negative indices count back from the end of the
|
|
array, and an index of -1 references the last element.
|
|
<P>
|
|
|
|
The += operator will append to an array variable when assigning
|
|
using the compound assignment syntax; see
|
|
<FONT SIZE=-1><B>PARAMETERS</B>
|
|
|
|
</FONT>
|
|
above.
|
|
<P>
|
|
|
|
Any element of an array may be referenced using
|
|
${<I>name</I>[<I>subscript</I>]}. The braces are required to avoid
|
|
conflicts with pathname expansion. If
|
|
<I>subscript</I> is <B>@</B> or <B>*</B>, the word expands to
|
|
all members of <I>name</I>. These subscripts differ only when the
|
|
word appears within double quotes. If the word is double-quoted,
|
|
${<I>name</I>[*]} expands to a single
|
|
word with the value of each array member separated by the first
|
|
character of the
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
special variable, and ${<I>name</I>[@]} expands each element of
|
|
<I>name</I> to a separate word. When there are no array members,
|
|
${<I>name</I>[@]} expands to nothing.
|
|
If the double-quoted expansion occurs within a word, the expansion of
|
|
the first parameter is joined with the beginning part of the original
|
|
word, and the expansion of the last parameter is joined with the last
|
|
part of the original word.
|
|
This is analogous to the expansion
|
|
of the special parameters <B>*</B> and <B>@</B> (see
|
|
<B>Special Parameters</B>
|
|
|
|
above). ${#<I>name</I>[<I>subscript</I>]} expands to the length of
|
|
${<I>name</I>[<I>subscript</I>]}. If <I>subscript</I> is <B>*</B> or
|
|
<B>@</B>, the expansion is the number of elements in the array.
|
|
If the
|
|
<I>subscript</I>
|
|
|
|
used to reference an element of an indexed array
|
|
evaluates to a number less than zero, it is
|
|
interpreted as relative to one greater than the maximum index of the array,
|
|
so negative indices count back from the end of the
|
|
array, and an index of -1 references the last element.
|
|
<P>
|
|
|
|
Referencing an array variable without a subscript is equivalent to
|
|
referencing the array with a subscript of 0.
|
|
Any reference to a variable using a valid subscript is legal, and
|
|
<B>bash</B>
|
|
|
|
will create an array if necessary.
|
|
<P>
|
|
|
|
An array variable is considered set if a subscript has been assigned a
|
|
value. The null string is a valid value.
|
|
<P>
|
|
|
|
It is possible to obtain the keys (indices) of an array as well as the values.
|
|
${<B>!</B><I>name</I>[<I>@</I>]} and ${<B>!</B><I>name</I>[<I>*</I>]}
|
|
expand to the indices assigned in array variable <I>name</I>.
|
|
The treatment when in double quotes is similar to the expansion of the
|
|
special parameters <I>@</I> and <I>*</I> within double quotes.
|
|
<P>
|
|
|
|
The
|
|
<B>unset</B>
|
|
|
|
builtin is used to destroy arrays. <B>unset</B> <I>name</I>[<I>subscript</I>]
|
|
destroys the array element at index <I>subscript</I>,
|
|
for both indexed and associative arrays.
|
|
Negative subscripts to indexed arrays are interpreted as described above.
|
|
Unsetting the last element of an array variable does not unset the variable.
|
|
<B>unset</B> <I>name</I>, where <I>name</I> is an array,
|
|
removes the entire array.
|
|
<B>unset</B> <I>name</I>[<I>subscript</I>], where
|
|
<I>subscript</I> is <B>*</B> or <B>@</B>, behaves differently depending on
|
|
whether <I>name</I> is an indexed or associative array.
|
|
If <I>name</I> is an associative array, this unsets the element with
|
|
subscript <B>*</B> or <B>@</B>.
|
|
If <I>name</I> is an indexed array, unset removes all of the elements but
|
|
does not remove the array itself.
|
|
<P>
|
|
|
|
When using a variable name with a subscript as an argument to a command,
|
|
such as with <B>unset</B>, without using the word expansion syntax
|
|
described above, the argument is subject to pathname expansion.
|
|
If pathname expansion is not desired, the argument should be quoted.
|
|
<P>
|
|
|
|
The
|
|
<B>declare</B>,
|
|
|
|
<B>local</B>,
|
|
|
|
and
|
|
<B>readonly</B>
|
|
|
|
builtins each accept a
|
|
<B>-a</B>
|
|
|
|
option to specify an indexed array and a
|
|
<B>-A</B>
|
|
|
|
option to specify an associative array.
|
|
If both options are supplied,
|
|
<B>-A</B>
|
|
|
|
takes precedence.
|
|
The
|
|
<B>read</B>
|
|
|
|
builtin accepts a
|
|
<B>-a</B>
|
|
|
|
option to assign a list of words read from the standard input
|
|
to an array. The
|
|
<B>set</B>
|
|
|
|
and
|
|
<B>declare</B>
|
|
|
|
builtins display array values in a way that allows them to be
|
|
reused as assignments.
|
|
<A NAME="lbAY"> </A>
|
|
<H3>EXPANSION</H3>
|
|
|
|
Expansion is performed on the command line after it has been split into
|
|
words. There are seven kinds of expansion performed:
|
|
<I>brace expansion</I>,
|
|
|
|
<I>tilde expansion</I>,
|
|
|
|
<I>parameter and variable expansion</I>,
|
|
|
|
<I>command substitution</I>,
|
|
|
|
<I>arithmetic expansion</I>,
|
|
|
|
<I>word splitting</I>,
|
|
|
|
and
|
|
<I>pathname expansion</I>.
|
|
|
|
<P>
|
|
|
|
The order of expansions is:
|
|
brace expansion;
|
|
tilde expansion, parameter and variable expansion, arithmetic expansion,
|
|
and command substitution (done in a left-to-right fashion);
|
|
word splitting;
|
|
and pathname expansion.
|
|
<P>
|
|
|
|
On systems that can support it, there is an additional expansion
|
|
available: <I>process substitution</I>.
|
|
This is performed at the
|
|
same time as tilde, parameter, variable, and arithmetic expansion and
|
|
command substitution.
|
|
<P>
|
|
|
|
After these expansions are performed, quote characters present in the
|
|
original word are removed unless they have been quoted themselves
|
|
(<I>quote removal</I>).
|
|
<P>
|
|
|
|
Only brace expansion, word splitting, and pathname expansion
|
|
can increase the number of words of the expansion; other expansions
|
|
expand a single word to a single word.
|
|
The only exceptions to this are the expansions of
|
|
"<B>$@</B>" and "<B>${</B><I>name</I><B>[@]}</B>",
|
|
and, in most cases, <B>$*</B> and <B>${</B><I>name</I><B>[*]}</B>
|
|
as explained above (see
|
|
<FONT SIZE=-1><B>PARAMETERS</B>).
|
|
|
|
</FONT>
|
|
<A NAME="lbAZ"> </A>
|
|
<H4>Brace Expansion</H4>
|
|
|
|
<I>Brace expansion</I>
|
|
|
|
is a mechanism by which arbitrary strings
|
|
may be generated. This mechanism is similar to
|
|
<I>pathname expansion</I>, but the filenames generated
|
|
need not exist. Patterns to be brace expanded take
|
|
the form of an optional
|
|
<I>preamble</I>,
|
|
|
|
followed by either a series of comma-separated strings or
|
|
a sequence expression between a pair of braces, followed by
|
|
an optional
|
|
<I>postscript</I>.
|
|
|
|
The preamble is prefixed to each string contained
|
|
within the braces, and the postscript is then appended
|
|
to each resulting string, expanding left to right.
|
|
<P>
|
|
|
|
Brace expansions may be nested. The results of each expanded
|
|
string are not sorted; left to right order is preserved.
|
|
For example, a<B>{</B>d,c,b<B>}</B>e expands into `ade ace abe'.
|
|
<P>
|
|
|
|
A sequence expression takes the form
|
|
<B>{</B><I>x</I><B>..</B><I>y</I><B>[..</B><I>incr</I><B>]}</B>,
|
|
where <I>x</I> and <I>y</I> are either integers or single letters,
|
|
and <I>incr</I>, an optional increment, is an integer.
|
|
When integers are supplied, the expression expands to each number between
|
|
<I>x</I> and <I>y</I>, inclusive.
|
|
Supplied integers may be prefixed with <I>0</I> to force each term to have the
|
|
same width.
|
|
When either <I>x</I> or y begins with a zero, the shell
|
|
attempts to force all generated terms to contain the same number of digits,
|
|
zero-padding where necessary.
|
|
When letters are supplied, the expression expands to each character
|
|
lexicographically between <I>x</I> and <I>y</I>, inclusive,
|
|
using the default C locale.
|
|
Note that both <I>x</I> and <I>y</I> must be of the same type
|
|
(integer or letter).
|
|
When the increment is supplied, it is used as the difference between
|
|
each term. The default increment is 1 or -1 as appropriate.
|
|
<P>
|
|
|
|
Brace expansion is performed before any other expansions,
|
|
and any characters special to other expansions are preserved
|
|
in the result. It is strictly textual.
|
|
<B>Bash</B>
|
|
|
|
does not apply any syntactic interpretation to the context of the
|
|
expansion or the text between the braces.
|
|
<P>
|
|
|
|
A correctly-formed brace expansion must contain unquoted opening
|
|
and closing braces, and at least one unquoted comma or a valid
|
|
sequence expression.
|
|
Any incorrectly formed brace expansion is left unchanged.
|
|
A <B>{</B> or <B>,</B> may be quoted with a backslash to prevent its
|
|
being considered part of a brace expression.
|
|
To avoid conflicts with parameter expansion, the string <B>${</B>
|
|
is not considered eligible for brace expansion, and inhibits brace
|
|
expansion until the closing <B>}</B>.
|
|
<P>
|
|
|
|
This construct is typically used as shorthand when the common
|
|
prefix of the strings to be generated is longer than in the
|
|
above example:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
mkdir /usr/local/src/bash/{old,new,dist,bugs}
|
|
</DL>
|
|
|
|
or
|
|
<DL COMPACT><DT><DD>
|
|
chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
Brace expansion introduces a slight incompatibility with
|
|
historical versions of
|
|
<B>sh</B>.
|
|
|
|
<B>sh</B>
|
|
|
|
does not treat opening or closing braces specially when they
|
|
appear as part of a word, and preserves them in the output.
|
|
<B>Bash</B>
|
|
|
|
removes braces from words as a consequence of brace
|
|
expansion. For example, a word entered to
|
|
<B>sh</B>
|
|
|
|
as <I>file{1,2}</I>
|
|
appears identically in the output. The same word is
|
|
output as
|
|
<I>file1 file2</I>
|
|
|
|
after expansion by
|
|
<B>bash</B>.
|
|
|
|
If strict compatibility with
|
|
<B>sh</B>
|
|
|
|
is desired, start
|
|
<B>bash</B>
|
|
|
|
with the
|
|
<B>+B</B>
|
|
|
|
option or disable brace expansion with the
|
|
<B>+B</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<A NAME="lbBA"> </A>
|
|
<H4>Tilde Expansion</H4>
|
|
|
|
If a word begins with an unquoted tilde character (`<B>~</B>'), all of
|
|
the characters preceding the first unquoted slash (or all characters,
|
|
if there is no unquoted slash) are considered a <I>tilde-prefix</I>.
|
|
If none of the characters in the tilde-prefix are quoted, the
|
|
characters in the tilde-prefix following the tilde are treated as a
|
|
possible <I>login name</I>.
|
|
If this login name is the null string, the tilde is replaced with the
|
|
value of the shell parameter
|
|
<FONT SIZE=-1><B>HOME</B>.
|
|
|
|
</FONT>
|
|
If
|
|
<FONT SIZE=-1><B>HOME</B>
|
|
|
|
</FONT>
|
|
is unset, the home directory of the user executing the shell is
|
|
substituted instead.
|
|
Otherwise, the tilde-prefix is replaced with the home directory
|
|
associated with the specified login name.
|
|
<P>
|
|
|
|
If the tilde-prefix is a `~+', the value of the shell variable
|
|
<FONT SIZE=-1><B>PWD</B>
|
|
|
|
</FONT>
|
|
replaces the tilde-prefix.
|
|
If the tilde-prefix is a `~-', the value of the shell variable
|
|
<FONT SIZE=-1><B>OLDPWD</B>,
|
|
|
|
</FONT>
|
|
if it is set, is substituted.
|
|
If the characters following the tilde in the tilde-prefix consist
|
|
of a number <I>N</I>, optionally prefixed
|
|
by a `+' or a `-', the tilde-prefix is replaced with the corresponding
|
|
element from the directory stack, as it would be displayed by the
|
|
<B>dirs</B>
|
|
|
|
builtin invoked with the tilde-prefix as an argument.
|
|
If the characters following the tilde in the tilde-prefix consist of a
|
|
number without a leading `+' or `-', `+' is assumed.
|
|
<P>
|
|
|
|
If the login name is invalid, or the tilde expansion fails, the word
|
|
is unchanged.
|
|
<P>
|
|
|
|
Each variable assignment is checked for unquoted tilde-prefixes immediately
|
|
following a
|
|
<B>:</B>
|
|
|
|
or the first
|
|
<B>=</B>.
|
|
|
|
In these cases, tilde expansion is also performed.
|
|
Consequently, one may use filenames with tildes in assignments to
|
|
<FONT SIZE=-1><B>PATH</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>MAILPATH</B>,
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>CDPATH</B>,
|
|
|
|
</FONT>
|
|
and the shell assigns the expanded value.
|
|
<P>
|
|
|
|
Bash also performs tilde expansion on words satisfying the conditions of
|
|
variable assignments (as described above under
|
|
<FONT SIZE=-1><B>PARAMETERS</B>)
|
|
|
|
</FONT>
|
|
when they appear as arguments to simple commands.
|
|
Bash does not do this, except for the <I>declaration</I> commands listed
|
|
above, when in <I>posix mode</I>.
|
|
<A NAME="lbBB"> </A>
|
|
<H4>Parameter Expansion</H4>
|
|
|
|
The `<B>$</B>' character introduces parameter expansion,
|
|
command substitution, or arithmetic expansion. The parameter name
|
|
or symbol to be expanded may be enclosed in braces, which
|
|
are optional but serve to protect the variable to be expanded from
|
|
characters immediately following it which could be
|
|
interpreted as part of the name.
|
|
<P>
|
|
|
|
When braces are used, the matching ending brace is the first `<B>}</B>'
|
|
not escaped by a backslash or within a quoted string, and not within an
|
|
embedded arithmetic expansion, command substitution, or parameter
|
|
expansion.
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT>${<I>parameter</I>}<DD>
|
|
The value of <I>parameter</I> is substituted. The braces are required
|
|
when
|
|
<I>parameter</I>
|
|
|
|
is a positional parameter with more than one digit,
|
|
or when
|
|
<I>parameter</I>
|
|
|
|
is followed by a character which is not to be
|
|
interpreted as part of its name.
|
|
The <I>parameter</I> is a shell parameter as described above
|
|
<B>PARAMETERS</B>) or an array reference (<B>Arrays</B>).
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If the first character of <I>parameter</I> is an exclamation point (<B>!</B>),
|
|
and <I>parameter</I> is not a <I>nameref</I>,
|
|
it introduces a level of indirection.
|
|
<B>Bash</B> uses the value formed by expanding the rest of
|
|
<I>parameter</I> as the new <I>parameter</I>; this is then
|
|
expanded and that value is used in the rest of the expansion, rather
|
|
than the expansion of the original <I>parameter</I>.
|
|
This is known as <I>indirect expansion</I>.
|
|
The value is subject to tilde expansion,
|
|
parameter expansion, command substitution, and arithmetic expansion.
|
|
If <I>parameter</I> is a nameref, this expands to the name of the
|
|
parameter referenced by <I>parameter</I> instead of performing the
|
|
complete indirect expansion.
|
|
The exceptions to this are the expansions of ${<B>!</B><I>prefix</I><B>*</B>} and
|
|
${<B>!</B><I>name</I>[<I>@</I>]} described below.
|
|
The exclamation point must immediately follow the left brace in order to
|
|
introduce indirection.
|
|
<P>
|
|
|
|
In each of the cases below, <I>word</I> is subject to tilde expansion,
|
|
parameter expansion, command substitution, and arithmetic expansion.
|
|
<P>
|
|
|
|
When not performing substring expansion, using the forms documented below
|
|
(e.g., <B>:-</B>),
|
|
<B>bash</B> tests for a parameter that is unset or null. Omitting the colon
|
|
results in a test only for a parameter that is unset.
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT>${<I>parameter</I><B>:-</B><I>word</I>}<DD>
|
|
<B>Use Default Values</B>. If
|
|
<I>parameter</I>
|
|
|
|
is unset or null, the expansion of
|
|
<I>word</I>
|
|
|
|
is substituted. Otherwise, the value of
|
|
<I>parameter</I>
|
|
|
|
is substituted.
|
|
<DT>${<I>parameter</I><B>:=</B><I>word</I>}<DD>
|
|
<B>Assign Default Values</B>.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is unset or null, the expansion of
|
|
<I>word</I>
|
|
|
|
is assigned to
|
|
<I>parameter</I>.
|
|
|
|
The value of
|
|
<I>parameter</I>
|
|
|
|
is then substituted. Positional parameters and special parameters may
|
|
not be assigned to in this way.
|
|
<DT>${<I>parameter</I><B>:?</B><I>word</I>}<DD>
|
|
<B>Display Error if Null or Unset</B>.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is null or unset, the expansion of <I>word</I> (or a message to that effect
|
|
if
|
|
<I>word</I>
|
|
|
|
is not present) is written to the standard error and the shell, if it
|
|
is not interactive, exits. Otherwise, the value of <I>parameter</I> is
|
|
substituted.
|
|
<DT>${<I>parameter</I><B>:+</B><I>word</I>}<DD>
|
|
<B>Use Alternate Value</B>.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is null or unset, nothing is substituted, otherwise the expansion of
|
|
<I>word</I>
|
|
|
|
is substituted.
|
|
<DT>${<I>parameter</I><B>:</B><I>offset</I>}<DD>
|
|
|
|
<DT>${<I>parameter</I><B>:</B><I>offset</I><B>:</B><I>length</I>}<DD>
|
|
|
|
<B>Substring Expansion</B>.
|
|
Expands to up to <I>length</I> characters of the value of <I>parameter</I>
|
|
starting at the character specified by <I>offset</I>.
|
|
If <I>parameter</I> is <B>@</B> or <B>*</B>, an indexed array subscripted by
|
|
<B>@</B> or <B>*</B>, or an associative array name, the results differ as
|
|
described below.
|
|
If <I>length</I> is omitted, expands to the substring of the value of
|
|
<I>parameter</I> starting at the character specified by <I>offset</I>
|
|
and extending to the end of the value.
|
|
<I>length</I> and <I>offset</I> are arithmetic expressions (see
|
|
<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<P>
|
|
If <I>offset</I> evaluates to a number less than zero, the value
|
|
is used as an offset in characters
|
|
from the end of the value of <I>parameter</I>.
|
|
If <I>length</I> evaluates to a number less than zero,
|
|
it is interpreted as an offset in characters
|
|
from the end of the value of <I>parameter</I> rather than
|
|
a number of characters, and the expansion is the characters between
|
|
<I>offset</I> and that result.
|
|
Note that a negative offset must be separated from the colon by at least
|
|
one space to avoid being confused with the <B>:-</B> expansion.
|
|
<P>
|
|
If <I>parameter</I> is <B>@</B> or <B>*</B>, the result is <I>length</I>
|
|
positional parameters beginning at <I>offset</I>.
|
|
A negative <I>offset</I> is taken relative to one greater than the greatest
|
|
positional parameter, so an offset of -1 evaluates to the last positional
|
|
parameter.
|
|
It is an expansion error if <I>length</I> evaluates to a number less than
|
|
zero.
|
|
<P>
|
|
If <I>parameter</I> is an indexed array name subscripted by @ or *,
|
|
the result is the <I>length</I>
|
|
members of the array beginning with ${<I>parameter</I>[<I>offset</I>]}.
|
|
A negative <I>offset</I> is taken relative to one greater than the maximum
|
|
index of the specified array.
|
|
It is an expansion error if <I>length</I> evaluates to a number less than
|
|
zero.
|
|
<P>
|
|
Substring expansion applied to an associative array produces undefined
|
|
results.
|
|
<P>
|
|
Substring indexing is zero-based unless the positional parameters
|
|
are used, in which case the indexing starts at 1 by default.
|
|
If <I>offset</I> is 0, and the positional parameters are used, <B>$0</B> is
|
|
prefixed to the list.
|
|
<DT>${<B>!</B><I>prefix</I><B>*</B>}<DD>
|
|
|
|
<DT>${<B>!</B><I>prefix</I><B>@</B>}<DD>
|
|
|
|
<B>Names matching prefix</B>.
|
|
Expands to the names of variables whose names begin with <I>prefix</I>,
|
|
separated by the first character of the
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
special variable.
|
|
When <I>@</I> is used and the expansion appears within double quotes, each
|
|
variable name expands to a separate word.
|
|
<DT>${<B>!</B><I>name</I>[<I>@</I>]}<DD>
|
|
|
|
<DT>${<B>!</B><I>name</I>[<I>*</I>]}<DD>
|
|
|
|
<B>List of array keys</B>.
|
|
If <I>name</I> is an array variable, expands to the list of array indices
|
|
(keys) assigned in <I>name</I>.
|
|
If <I>name</I> is not an array, expands to 0 if <I>name</I> is set and null
|
|
otherwise.
|
|
When <I>@</I> is used and the expansion appears within double quotes, each
|
|
key expands to a separate word.
|
|
<DT>${<B>#</B><I>parameter</I>}<DD>
|
|
<B>Parameter length</B>.
|
|
The length in characters of the value of <I>parameter</I> is substituted.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is
|
|
<B>*</B>
|
|
|
|
or
|
|
<B>@</B>,
|
|
|
|
the value substituted is the number of positional parameters.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is an array name subscripted by
|
|
<B>*</B>
|
|
|
|
or
|
|
<B>@</B>,
|
|
|
|
the value substituted is the number of elements in the array.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is an indexed array name subscripted by a negative number, that number is
|
|
interpreted as relative to one greater than the maximum index of
|
|
<I>parameter</I>, so negative indices count back from the end of the
|
|
array, and an index of -1 references the last element.
|
|
<DT>${<I>parameter</I><B>#</B><I>word</I>}<DD>
|
|
|
|
<DT>${<I>parameter</I><B>##</B><I>word</I>}<DD>
|
|
|
|
<B>Remove matching prefix pattern</B>.
|
|
The
|
|
<I>word</I>
|
|
|
|
is expanded to produce a pattern just as in pathname
|
|
expansion, and matched against the expanded value of
|
|
<I>parameter</I>
|
|
|
|
using the rules described under
|
|
<B>Pattern Matching</B>
|
|
|
|
below.
|
|
If the pattern matches the beginning of
|
|
the value of
|
|
<I>parameter</I>,
|
|
|
|
then the result of the expansion is the expanded value of
|
|
<I>parameter</I>
|
|
|
|
with the shortest matching pattern (the ``<B>#</B>'' case) or the
|
|
longest matching pattern (the ``<B>##</B>'' case) deleted.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the pattern removal operation is applied to each positional
|
|
parameter in turn, and the expansion is the resultant list.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is an array variable subscripted with
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the pattern removal operation is applied to each member of the
|
|
array in turn, and the expansion is the resultant list.
|
|
<DT>${<I>parameter</I><B>%</B><I>word</I>}<DD>
|
|
|
|
<DT>${<I>parameter</I><B>%%</B><I>word</I>}<DD>
|
|
|
|
<B>Remove matching suffix pattern</B>.
|
|
The <I>word</I> is expanded to produce a pattern just as in
|
|
pathname expansion, and matched against the expanded value of
|
|
<I>parameter</I>
|
|
|
|
using the rules described under
|
|
<B>Pattern Matching</B>
|
|
|
|
below.
|
|
If the pattern matches a trailing portion of the expanded value of
|
|
<I>parameter</I>,
|
|
|
|
then the result of the expansion is the expanded value of
|
|
<I>parameter</I>
|
|
|
|
with the shortest matching pattern (the ``<B>%</B>'' case) or the
|
|
longest matching pattern (the ``<B>%%</B>'' case) deleted.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the pattern removal operation is applied to each positional
|
|
parameter in turn, and the expansion is the resultant list.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is an array variable subscripted with
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the pattern removal operation is applied to each member of the
|
|
array in turn, and the expansion is the resultant list.
|
|
<DT>${<I>parameter</I><B>/</B><I>pattern</I><B>/</B><I>string</I>}<DD>
|
|
|
|
<DT>${<I>parameter</I><B>//</B><I>pattern</I><B>/</B><I>string</I>}<DD>
|
|
<DT>${<I>parameter</I><B>/#</B><I>pattern</I><B>/</B><I>string</I>}<DD>
|
|
<DT>${<I>parameter</I><B>/%</B><I>pattern</I><B>/</B><I>string</I>}<DD>
|
|
|
|
<B>Pattern substitution</B>.
|
|
The <I>pattern</I> is expanded to produce a pattern just as in
|
|
pathname expansion.
|
|
<I>Parameter</I> is expanded and the longest match of <I>pattern</I>
|
|
against its value is replaced with <I>string</I>.
|
|
<I>string</I> undergoes tilde expansion, parameter and variable expansion,
|
|
arithmetic expansion, command and process substitution, and quote removal.
|
|
The match is performed using the rules described under
|
|
<B>Pattern Matching</B>
|
|
|
|
below.
|
|
In the first form above, only the first match is replaced.
|
|
If there are two slashes separating <I>parameter</I> and <I>pattern</I>
|
|
(the second form above), all matches of <I>pattern</I> are
|
|
replaced with <I>string</I>.
|
|
If <I>pattern</I> is preceded by <B>#</B> (the third form above),
|
|
it must match at the beginning of the expanded value of <I>parameter</I>.
|
|
If <I>pattern</I> is preceded by <B>%</B> (the fourth form above),
|
|
it must match at the end of the expanded value of <I>parameter</I>.
|
|
If the expansion of <I>string</I> is null,
|
|
matches of <I>pattern</I> are deleted.
|
|
If <I>string</I> is null,
|
|
matches of <I>pattern</I> are deleted
|
|
and the <B>/</B> following <I>pattern</I> may be omitted.
|
|
<P>
|
|
If the <B>patsub_replacement</B> shell option is enabled using <B>shopt</B>,
|
|
any unquoted instances of <B>&</B> in <I>string</I> are replaced with the
|
|
matching portion of <I>pattern</I>.
|
|
<P>
|
|
Quoting any part of <I>string</I> inhibits replacement in the
|
|
expansion of the quoted portion, including replacement strings stored
|
|
in shell variables.
|
|
Backslash will escape <B>&</B> in <I>string</I>; the backslash is removed
|
|
in order to permit a literal <B>&</B> in the replacement string.
|
|
Backslash can also be used to escape a backslash; <B>\\</B> results in
|
|
a literal backslash in the replacement.
|
|
Users should take care if <I>string</I> is double-quoted to avoid
|
|
unwanted interactions between the backslash and double-quoting, since
|
|
backslash has special meaning within double quotes.
|
|
Pattern substitution performs the check for unquoted <B>&</B> after
|
|
expanding <I>string</I>;
|
|
shell programmers should quote any occurrences of <B>&</B>
|
|
they want to be taken literally in the replacement
|
|
and ensure any instances of <B>&</B> they want to be replaced are unquoted.
|
|
<P>
|
|
If the
|
|
<B>nocasematch</B>
|
|
|
|
shell option is enabled, the match is performed without regard to the case
|
|
of alphabetic characters.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the substitution operation is applied to each positional
|
|
parameter in turn, and the expansion is the resultant list.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is an array variable subscripted with
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the substitution operation is applied to each member of the
|
|
array in turn, and the expansion is the resultant list.
|
|
<DT>${<I>parameter</I><B>^</B><I>pattern</I>}<DD>
|
|
|
|
<DT>${<I>parameter</I><B>^^</B><I>pattern</I>}<DD>
|
|
<DT>${<I>parameter</I><B>,</B><I>pattern</I>}<DD>
|
|
<DT>${<I>parameter</I><B>,,</B><I>pattern</I>}<DD>
|
|
|
|
<B>Case modification</B>.
|
|
This expansion modifies the case of alphabetic characters in <I>parameter</I>.
|
|
The <I>pattern</I> is expanded to produce a pattern just as in
|
|
pathname expansion.
|
|
Each character in the expanded value of <I>parameter</I> is tested against
|
|
<I>pattern</I>, and, if it matches the pattern, its case is converted.
|
|
The pattern should not attempt to match more than one character.
|
|
The <B>^</B> operator converts lowercase letters matching <I>pattern</I>
|
|
to uppercase; the <B>,</B> operator converts matching uppercase letters
|
|
to lowercase.
|
|
The <B>^^</B> and <B>,,</B> expansions convert each matched character in the
|
|
expanded value; the <B>^</B> and <B>,</B> expansions match and convert only
|
|
the first character in the expanded value.
|
|
If <I>pattern</I> is omitted, it is treated like a <B>?</B>, which matches
|
|
every character.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the case modification operation is applied to each positional
|
|
parameter in turn, and the expansion is the resultant list.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is an array variable subscripted with
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the case modification operation is applied to each member of the
|
|
array in turn, and the expansion is the resultant list.
|
|
<DT>${<I>parameter</I><B>@</B><I>operator</I>}<DD>
|
|
<B>Parameter transformation</B>.
|
|
The expansion is either a transformation of the value of <I>parameter</I>
|
|
or information about <I>parameter</I> itself, depending on the value of
|
|
<I>operator</I>. Each <I>operator</I> is a single letter:
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>U</B>
|
|
|
|
<DD>
|
|
The expansion is a string that is the value of <I>parameter</I> with lowercase
|
|
alphabetic characters converted to uppercase.
|
|
<DT><B>u</B>
|
|
|
|
<DD>
|
|
The expansion is a string that is the value of <I>parameter</I> with the first
|
|
character converted to uppercase, if it is alphabetic.
|
|
<DT><B>L</B>
|
|
|
|
<DD>
|
|
The expansion is a string that is the value of <I>parameter</I> with uppercase
|
|
alphabetic characters converted to lowercase.
|
|
<DT><B>Q</B>
|
|
|
|
<DD>
|
|
The expansion is a string that is the value of <I>parameter</I> quoted in a
|
|
format that can be reused as input.
|
|
<DT><B>E</B>
|
|
|
|
<DD>
|
|
The expansion is a string that is the value of <I>parameter</I> with backslash
|
|
escape sequences expanded as with the <B>$aq...aq</B> quoting mechanism.
|
|
<DT><B>P</B>
|
|
|
|
<DD>
|
|
The expansion is a string that is the result of expanding the value of
|
|
<I>parameter</I> as if it were a prompt string (see <B>PROMPTING</B> below).
|
|
<DT><B>A</B>
|
|
|
|
<DD>
|
|
The expansion is a string in the form of
|
|
an assignment statement or <B>declare</B> command that, if
|
|
evaluated, will recreate <I>parameter</I> with its attributes and value.
|
|
<DT><B>K</B>
|
|
|
|
<DD>
|
|
Produces a possibly-quoted version of the value of <I>parameter</I>,
|
|
except that it prints the values of
|
|
indexed and associative arrays as a sequence of quoted key-value pairs
|
|
(see <B>Arrays</B> above).
|
|
<DT><B>a</B>
|
|
|
|
<DD>
|
|
The expansion is a string consisting of flag values representing
|
|
<I>parameter</I>'s attributes.
|
|
<DT><B>k</B>
|
|
|
|
<DD>
|
|
Like the K transformation, but expands the keys and values of
|
|
indexed and associative arrays to separate words after word splitting.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the operation is applied to each positional
|
|
parameter in turn, and the expansion is the resultant list.
|
|
If
|
|
<I>parameter</I>
|
|
|
|
is an array variable subscripted with
|
|
<B>@</B>
|
|
|
|
or
|
|
<B>*</B>,
|
|
|
|
the operation is applied to each member of the
|
|
array in turn, and the expansion is the resultant list.
|
|
<P>
|
|
The result of the expansion is subject to word splitting and pathname
|
|
expansion as described below.
|
|
</DL>
|
|
|
|
</DL>
|
|
<A NAME="lbBC"> </A>
|
|
<H4>Command Substitution</H4>
|
|
|
|
<I>Command substitution</I> allows the output of a command to replace
|
|
the command name. There are two forms:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>$(</B><I>command</I><B>)</B>
|
|
</DL>
|
|
|
|
or
|
|
<DL COMPACT><DT><DD>
|
|
<B>`</B><I>command</I><B>`</B>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
<B>Bash</B>
|
|
|
|
performs the expansion by executing <I>command</I> in a subshell environment
|
|
and replacing the command substitution with the standard output of the
|
|
command, with any trailing newlines deleted.
|
|
Embedded newlines are not deleted, but they may be removed during
|
|
word splitting.
|
|
The command substitution <B>$(cat </B><I>file</I>) can be replaced by
|
|
the equivalent but faster <B>$(< </B><I>file</I>).
|
|
<P>
|
|
|
|
When the old-style backquote form of substitution is used,
|
|
backslash retains its literal meaning except when followed by
|
|
<B>$</B>,
|
|
|
|
<B>`</B>,
|
|
|
|
or
|
|
<B>\</B>.
|
|
|
|
The first backquote not preceded by a backslash terminates the
|
|
command substitution.
|
|
When using the $(<I>command</I>) form, all characters between the
|
|
parentheses make up the command; none are treated specially.
|
|
<P>
|
|
|
|
Command substitutions may be nested. To nest when using the backquoted form,
|
|
escape the inner backquotes with backslashes.
|
|
<P>
|
|
|
|
If the substitution appears within double quotes, word splitting and
|
|
pathname expansion are not performed on the results.
|
|
<A NAME="lbBD"> </A>
|
|
<H4>Arithmetic Expansion</H4>
|
|
|
|
Arithmetic expansion allows the evaluation of an arithmetic expression
|
|
and the substitution of the result. The format for arithmetic expansion is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>$((</B><I>expression</I><B>))</B>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
The
|
|
<I>expression</I>
|
|
|
|
undergoes the same expansions
|
|
as if it were within double quotes,
|
|
but double quote characters in <I>expression</I> are not treated specially
|
|
and are removed.
|
|
All tokens in the expression undergo parameter and variable expansion,
|
|
command substitution, and quote removal.
|
|
The result is treated as the arithmetic expression to be evaluated.
|
|
Arithmetic expansions may be nested.
|
|
<P>
|
|
|
|
The evaluation is performed according to the rules listed below under
|
|
<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>.
|
|
|
|
</FONT>
|
|
If
|
|
<I>expression</I>
|
|
|
|
is invalid,
|
|
<B>bash</B>
|
|
|
|
prints a message indicating failure and no substitution occurs.
|
|
<A NAME="lbBE"> </A>
|
|
<H4>Process Substitution</H4>
|
|
|
|
<I>Process substitution</I> allows a process's input or output to be
|
|
referred to using a filename.
|
|
It takes the form of
|
|
<B><(</B><I>list</I><B>)</B>
|
|
or
|
|
<B>>(</B><I>list</I><B>)</B>.
|
|
The process <I>list</I> is run asynchronously, and its input or output
|
|
appears as a filename.
|
|
This filename is
|
|
passed as an argument to the current command as the result of the
|
|
expansion.
|
|
If the <B>>(</B><I>list</I><B>)</B> form is used, writing to
|
|
the file will provide input for <I>list</I>. If the
|
|
<B><(</B><I>list</I><B>)</B> form is used, the file passed as an
|
|
argument should be read to obtain the output of <I>list</I>.
|
|
Process substitution is supported on systems that support named
|
|
pipes (<I>FIFOs</I>) or the <B>/dev/fd</B> method of naming open files.
|
|
<P>
|
|
|
|
When available, process substitution is performed
|
|
simultaneously with parameter and variable expansion,
|
|
command substitution,
|
|
and arithmetic expansion.
|
|
<A NAME="lbBF"> </A>
|
|
<H4>Word Splitting</H4>
|
|
|
|
The shell scans the results of
|
|
parameter expansion,
|
|
command substitution,
|
|
and
|
|
arithmetic expansion
|
|
that did not occur within double quotes for
|
|
<I>word splitting</I>.
|
|
|
|
<P>
|
|
|
|
The shell treats each character of
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
as a delimiter, and splits the results of the other
|
|
expansions into words using these characters as field terminators.
|
|
If
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
is unset, or its
|
|
value is exactly
|
|
<B><space><tab><newline></B>,
|
|
|
|
the default, then
|
|
sequences of
|
|
<B><space></B>,
|
|
|
|
<B><tab></B>,
|
|
|
|
and
|
|
<B><newline></B>
|
|
|
|
at the beginning and end of the results of the previous
|
|
expansions are ignored, and
|
|
any sequence of
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
characters not at the beginning or end serves to delimit words.
|
|
If
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
has a value other than the default, then sequences of
|
|
the whitespace characters
|
|
<B>space</B>,
|
|
|
|
<B>tab</B>,
|
|
|
|
and
|
|
<B>newline</B>
|
|
|
|
are ignored at the beginning and end of the
|
|
word, as long as the whitespace character is in the
|
|
value of
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
(an
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
whitespace character).
|
|
Any character in
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
that is not
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
whitespace, along with any adjacent
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
whitespace characters, delimits a field.
|
|
A sequence of
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
whitespace characters is also treated as a delimiter.
|
|
If the value of
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
is null, no word splitting occurs.
|
|
<P>
|
|
|
|
Explicit null arguments (<B>""</B> or <B>aqaq</B>) are retained
|
|
and passed to commands as empty strings.
|
|
Unquoted implicit null arguments, resulting from the expansion of
|
|
parameters that have no values, are removed.
|
|
If a parameter with no value is expanded within double quotes, a
|
|
null argument results and is retained
|
|
and passed to a command as an empty string.
|
|
When a quoted null argument appears as part of a word whose expansion is
|
|
non-null, the null argument is removed.
|
|
That is, the word
|
|
<TT>-daqaq</TT> becomes <TT>-d</TT> after word splitting and
|
|
null argument removal.
|
|
<P>
|
|
|
|
Note that if no expansion occurs, no splitting
|
|
is performed.
|
|
<A NAME="lbBG"> </A>
|
|
<H4>Pathname Expansion</H4>
|
|
|
|
After word splitting,
|
|
unless the
|
|
<B>-f</B>
|
|
|
|
option has been set,
|
|
<B>bash</B>
|
|
|
|
scans each word for the characters
|
|
<B>*</B>,
|
|
|
|
<B>?</B>,
|
|
|
|
and
|
|
<B>[</B>.
|
|
|
|
If one of these characters appears, and is not quoted, then the word is
|
|
regarded as a
|
|
<I>pattern</I>,
|
|
|
|
and replaced with an alphabetically sorted list of
|
|
filenames matching the pattern
|
|
(see
|
|
<FONT SIZE=-1><B>Pattern Matching</B>
|
|
|
|
</FONT>
|
|
below).
|
|
If no matching filenames are found,
|
|
and the shell option
|
|
<B>nullglob</B>
|
|
|
|
is not enabled, the word is left unchanged.
|
|
If the
|
|
<B>nullglob</B>
|
|
|
|
option is set, and no matches are found,
|
|
the word is removed.
|
|
If the
|
|
<B>failglob</B>
|
|
|
|
shell option is set, and no matches are found, an error message
|
|
is printed and the command is not executed.
|
|
If the shell option
|
|
<B>nocaseglob</B>
|
|
|
|
is enabled, the match is performed without regard to the case
|
|
of alphabetic characters.
|
|
When a pattern is used for pathname expansion,
|
|
the character
|
|
<B>``.''</B>
|
|
|
|
at the start of a name or immediately following a slash
|
|
must be matched explicitly, unless the shell option
|
|
<B>dotglob</B>
|
|
|
|
is set.
|
|
In order to match the filenames
|
|
<B>``.''</B>
|
|
|
|
and
|
|
<B>``..''</B>,
|
|
|
|
the pattern must begin with ``.'' (for example, ``.?''),
|
|
even if
|
|
<B>dotglob</B>
|
|
|
|
is set.
|
|
If the
|
|
<B>globskipdots</B>
|
|
|
|
shell option is enabled, the filenames
|
|
<B>``.''</B>
|
|
|
|
and
|
|
<B>``..''</B>
|
|
|
|
are never matched, even if the pattern begins with a
|
|
<B>``.''</B>.
|
|
|
|
When not matching pathnames, the
|
|
<B>``.''</B>
|
|
|
|
character is not treated specially.
|
|
When matching a pathname, the slash character must always be
|
|
matched explicitly by a slash in the pattern, but in other matching
|
|
contexts it can be matched by a special pattern character as described
|
|
below under
|
|
<FONT SIZE=-1><B>Pattern Matching</B>.
|
|
|
|
</FONT>
|
|
See the description of
|
|
<B>shopt</B>
|
|
|
|
below under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
for a description of the
|
|
<B>nocaseglob</B>,
|
|
|
|
<B>nullglob</B>,
|
|
|
|
<B>globskipdots</B>,
|
|
|
|
<B>failglob</B>,
|
|
|
|
and
|
|
<B>dotglob</B>
|
|
|
|
shell options.
|
|
<P>
|
|
|
|
The
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
shell variable may be used to restrict the set of file names matching a
|
|
<I>pattern</I>.
|
|
|
|
If
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
is set, each matching file name that also matches one of the patterns in
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
is removed from the list of matches.
|
|
If the <B>nocaseglob</B> option is set, the matching against the patterns in
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
is performed without regard to case.
|
|
The filenames
|
|
<B>``.''</B>
|
|
|
|
and
|
|
<B>``..''</B>
|
|
|
|
are always ignored when
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
is set and not null. However, setting
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
to a non-null value has the effect of enabling the
|
|
<B>dotglob</B>
|
|
|
|
shell option, so all other filenames beginning with a
|
|
<B>``.''</B>
|
|
|
|
will match.
|
|
To get the old behavior of ignoring filenames beginning with a
|
|
<B>``.''</B>,
|
|
|
|
make
|
|
<B>``.*''</B>
|
|
|
|
one of the patterns in
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>.
|
|
|
|
</FONT>
|
|
The
|
|
<B>dotglob</B>
|
|
|
|
option is disabled when
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
is unset.
|
|
The pattern matching honors the setting of the <B>extglob</B> shell
|
|
option.
|
|
<P>
|
|
|
|
<B>Pattern Matching</B>
|
|
<P>
|
|
|
|
Any character that appears in a pattern, other than the special pattern
|
|
characters described below, matches itself. The NUL character may not
|
|
occur in a pattern. A backslash escapes the following character; the
|
|
escaping backslash is discarded when matching.
|
|
The special pattern characters must be quoted if
|
|
they are to be matched literally.
|
|
<P>
|
|
|
|
The special pattern characters have the following meanings:
|
|
<P>
|
|
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>*</B>
|
|
|
|
<DD>
|
|
Matches any string, including the null string.
|
|
When the <B>globstar</B> shell option is enabled, and <B>*</B> is used in
|
|
a pathname expansion context, two adjacent <B>*</B>s used as a single
|
|
pattern will match all files and zero or more directories and
|
|
subdirectories.
|
|
If followed by a <B>/</B>, two adjacent <B>*</B>s will match only directories
|
|
and subdirectories.
|
|
<DT><B>?</B>
|
|
|
|
<DD>
|
|
Matches any single character.
|
|
<DT><B>[...]</B>
|
|
|
|
<DD>
|
|
Matches any one of the enclosed characters. A pair of characters
|
|
separated by a hyphen denotes a
|
|
<I>range expression</I>;
|
|
any character that falls between those two characters, inclusive,
|
|
using the current locale's collating sequence and character set,
|
|
is matched. If the first character following the
|
|
<B>[</B>
|
|
|
|
is a
|
|
<B>!</B>
|
|
|
|
or a
|
|
<B>^</B>
|
|
|
|
then any character not enclosed is matched.
|
|
The sorting order of characters in range expressions,
|
|
and the characters included in the range,
|
|
are determined by
|
|
the current locale and the values of the
|
|
<FONT SIZE=-1><B>LC_COLLATE</B>
|
|
|
|
</FONT>
|
|
or
|
|
<FONT SIZE=-1><B>LC_ALL</B>
|
|
|
|
</FONT>
|
|
shell variables, if set.
|
|
To obtain the traditional interpretation of range expressions, where
|
|
<B>[a-d]</B>
|
|
|
|
is equivalent to
|
|
<B>[abcd]</B>,
|
|
|
|
set value of the
|
|
<B>LC_ALL</B>
|
|
|
|
shell variable to
|
|
<B>C</B>,
|
|
|
|
or enable the
|
|
<B>globasciiranges</B>
|
|
|
|
shell option.
|
|
A
|
|
<B>-</B>
|
|
|
|
may be matched by including it as the first or last character
|
|
in the set.
|
|
A
|
|
<B>]</B>
|
|
|
|
may be matched by including it as the first character
|
|
in the set.
|
|
<BR>
|
|
|
|
<P>
|
|
|
|
|
|
Within
|
|
<B>[</B>
|
|
|
|
and
|
|
<B>]</B>,
|
|
|
|
<I>character classes</I> can be specified using the syntax
|
|
<B>[:</B><I>class</I><B>:]</B>, where <I>class</I> is one of the
|
|
following classes defined in the POSIX standard:
|
|
</DL>
|
|
<P>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<B>
|
|
</B>
|
|
|
|
alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit
|
|
<BR>
|
|
|
|
A character class matches any character belonging to that class.
|
|
The <B>word</B> character class matches letters, digits, and the character _.
|
|
<BR>
|
|
|
|
<P>
|
|
|
|
|
|
Within
|
|
<B>[</B>
|
|
|
|
and
|
|
<B>]</B>,
|
|
|
|
an <I>equivalence class</I> can be specified using the syntax
|
|
<B>[=</B><I>c</I><B>=]</B>, which matches all characters with the
|
|
same collation weight (as defined by the current locale) as
|
|
the character <I>c</I>.
|
|
<BR>
|
|
|
|
<P>
|
|
|
|
|
|
Within
|
|
<B>[</B>
|
|
|
|
and
|
|
<B>]</B>,
|
|
|
|
the syntax <B>[.</B><I>symbol</I><B>.]</B> matches the collating symbol
|
|
<I>symbol</I>.
|
|
</DL>
|
|
|
|
</DL>
|
|
|
|
|
|
<P>
|
|
|
|
If the <B>extglob</B> shell option is enabled using the <B>shopt</B>
|
|
builtin, the shell recognizes several extended pattern matching operators.
|
|
In the following description, a <I>pattern-list</I> is a list of one
|
|
or more patterns separated by a <B>|</B>.
|
|
Composite patterns may be formed using one or more of the following
|
|
sub-patterns:
|
|
<P>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>?(</B><I>pattern-list</I><B>)</B><DD>
|
|
Matches zero or one occurrence of the given patterns
|
|
<DT><B>*(</B><I>pattern-list</I><B>)</B><DD>
|
|
Matches zero or more occurrences of the given patterns
|
|
<DT><B>+(</B><I>pattern-list</I><B>)</B><DD>
|
|
Matches one or more occurrences of the given patterns
|
|
<DT><B>@(</B><I>pattern-list</I><B>)</B><DD>
|
|
Matches one of the given patterns
|
|
<DT><B>!(</B><I>pattern-list</I><B>)</B><DD>
|
|
Matches anything except one of the given patterns
|
|
</DL></DL>
|
|
|
|
|
|
<P>
|
|
|
|
The<B>extglob</B> option changes the behavior of the parser, since the
|
|
parentheses are normally treated as operators with syntactic meaning.
|
|
To ensure that extended matching patterns are parsed correctly, make sure
|
|
that <B>extglob</B> is enabled before parsing constructs containing the
|
|
patterns, including shell functions and command substitutions.
|
|
<P>
|
|
|
|
When matching filenames, the <B>dotglob</B> shell option determines
|
|
the set of filenames that are tested:
|
|
when <B>dotglob</B> is enabled, the set of filenames includes all files
|
|
beginning with ``.'', but ``.'' and ``..'' must be matched by a
|
|
pattern or sub-pattern that begins with a dot;
|
|
when it is disabled, the set does not
|
|
include any filenames beginning with ``.'' unless the pattern
|
|
or sub-pattern begins with a ``.''.
|
|
As above, ``.'' only has a special meaning when matching filenames.
|
|
<P>
|
|
|
|
Complicated extended pattern matching against long strings is slow,
|
|
especially when the patterns contain alternations and the strings
|
|
contain multiple matches.
|
|
Using separate matches against shorter strings, or using arrays of
|
|
strings instead of a single long string, may be faster.
|
|
<A NAME="lbBH"> </A>
|
|
<H4>Quote Removal</H4>
|
|
|
|
After the preceding expansions, all unquoted occurrences of the
|
|
characters
|
|
<B>\</B>,
|
|
|
|
<B>aq</B>,
|
|
|
|
and <B>"</B> that did not result from one of the above
|
|
expansions are removed.
|
|
<A NAME="lbBI"> </A>
|
|
<H3>REDIRECTION</H3>
|
|
|
|
Before a command is executed, its input and output
|
|
may be
|
|
<I>redirected</I>
|
|
|
|
using a special notation interpreted by the shell.
|
|
<I>Redirection</I> allows commands' file handles to be
|
|
duplicated, opened, closed,
|
|
made to refer to different files,
|
|
and can change the files the command reads from and writes to.
|
|
Redirection may also be used to modify file handles in the
|
|
current shell execution environment.
|
|
The following redirection
|
|
operators may precede or appear anywhere within a
|
|
<I>simple command</I>
|
|
|
|
or may follow a
|
|
<I>command</I>.
|
|
|
|
Redirections are processed in the order they appear, from
|
|
left to right.
|
|
<P>
|
|
|
|
Each redirection that may be preceded by a file descriptor number
|
|
may instead be preceded by a word of the form {<I>varname</I>}.
|
|
In this case, for each redirection operator except
|
|
>&- and <&-, the shell will allocate a file descriptor greater
|
|
than or equal to 10 and assign it to <I>varname</I>.
|
|
If >&- or <&- is preceded
|
|
by {<I>varname</I>}, the value of <I>varname</I> defines the file
|
|
descriptor to close.
|
|
If {<I>varname</I>} is supplied, the redirection persists beyond
|
|
the scope of the command, allowing the shell programmer to manage
|
|
the file descriptor's lifetime manually.
|
|
The <B>varredir_close</B> shell option manages this behavior.
|
|
<P>
|
|
|
|
In the following descriptions, if the file descriptor number is
|
|
omitted, and the first character of the redirection operator is
|
|
<B><</B>,
|
|
|
|
the redirection refers to the standard input (file descriptor
|
|
0). If the first character of the redirection operator is
|
|
<B>></B>,
|
|
|
|
the redirection refers to the standard output (file descriptor
|
|
1).
|
|
<P>
|
|
|
|
The word following the redirection operator in the following
|
|
descriptions, unless otherwise noted, is subjected to
|
|
brace expansion, tilde expansion, parameter and variable expansion,
|
|
command substitution, arithmetic expansion, quote removal,
|
|
pathname expansion, and word splitting.
|
|
If it expands to more than one word,
|
|
<B>bash</B>
|
|
|
|
reports an error.
|
|
<P>
|
|
|
|
Note that the order of redirections is significant. For example,
|
|
the command
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
ls <B>></B> dirlist 2<B>>&</B>1
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
directs both standard output and standard error to the file
|
|
<I>dirlist</I>,
|
|
|
|
while the command
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
ls 2<B>>&</B>1 <B>></B> dirlist
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
directs only the standard output to file
|
|
<I>dirlist</I>,
|
|
|
|
because the standard error was duplicated from the standard output
|
|
before the standard output was redirected to
|
|
<I>dirlist</I>.
|
|
|
|
<P>
|
|
|
|
<B>Bash</B> handles several filenames specially when they are used in
|
|
redirections, as described in the following table.
|
|
If the operating system on which <B>bash</B> is running provides these
|
|
special files, bash will use them; otherwise it will emulate them
|
|
internally with the behavior described below.
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>/dev/fd/</B><I>fd</I>
|
|
|
|
<DD>
|
|
If <I>fd</I> is a valid integer, file descriptor <I>fd</I> is duplicated.
|
|
<DT><B>/dev/stdin</B>
|
|
|
|
<DD>
|
|
File descriptor 0 is duplicated.
|
|
<DT><B>/dev/stdout</B>
|
|
|
|
<DD>
|
|
File descriptor 1 is duplicated.
|
|
<DT><B>/dev/stderr</B>
|
|
|
|
<DD>
|
|
File descriptor 2 is duplicated.
|
|
<DT><B>/dev/tcp/</B><I>host</I>/<I>port</I>
|
|
|
|
<DD>
|
|
If <I>host</I> is a valid hostname or Internet address, and <I>port</I>
|
|
is an integer port number or service name, <B>bash</B> attempts to open
|
|
the corresponding TCP socket.
|
|
<DT><B>/dev/udp/</B><I>host</I>/<I>port</I>
|
|
|
|
<DD>
|
|
If <I>host</I> is a valid hostname or Internet address, and <I>port</I>
|
|
is an integer port number or service name, <B>bash</B> attempts to open
|
|
the corresponding UDP socket.
|
|
|
|
</DL></DL>
|
|
|
|
<P>
|
|
|
|
A failure to open or create a file causes the redirection to fail.
|
|
<P>
|
|
|
|
Redirections using file descriptors greater than 9 should be used with
|
|
care, as they may conflict with file descriptors the shell uses
|
|
internally.
|
|
<A NAME="lbBJ"> </A>
|
|
<H4>Redirecting Input</H4>
|
|
|
|
Redirection of input causes the file whose name results from
|
|
the expansion of
|
|
<I>word</I>
|
|
|
|
to be opened for reading on file descriptor
|
|
<I>n</I>,
|
|
|
|
or the standard input (file descriptor 0) if
|
|
<I>n</I>
|
|
|
|
is not specified.
|
|
<P>
|
|
|
|
The general format for redirecting input is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B><</B><I>word</I>
|
|
</DL>
|
|
|
|
<A NAME="lbBK"> </A>
|
|
<H4>Redirecting Output</H4>
|
|
|
|
Redirection of output causes the file whose name results from
|
|
the expansion of
|
|
<I>word</I>
|
|
|
|
to be opened for writing on file descriptor
|
|
<I>n</I>,
|
|
|
|
or the standard output (file descriptor 1) if
|
|
<I>n</I>
|
|
|
|
is not specified. If the file does not exist it is created;
|
|
if it does exist it is truncated to zero size.
|
|
<P>
|
|
|
|
The general format for redirecting output is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B>></B><I>word</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
If the redirection operator is
|
|
<B>></B>,
|
|
|
|
and the
|
|
<B>noclobber</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin has been enabled, the redirection will fail if the file
|
|
whose name results from the expansion of <I>word</I> exists and is
|
|
a regular file.
|
|
If the redirection operator is
|
|
<B>>|</B>,
|
|
|
|
or the redirection operator is
|
|
<B>></B>
|
|
|
|
and the
|
|
<B>noclobber</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin command is not enabled, the redirection is attempted even
|
|
if the file named by <I>word</I> exists.
|
|
<A NAME="lbBL"> </A>
|
|
<H4>Appending Redirected Output</H4>
|
|
|
|
Redirection of output in this fashion
|
|
causes the file whose name results from
|
|
the expansion of
|
|
<I>word</I>
|
|
|
|
to be opened for appending on file descriptor
|
|
<I>n</I>,
|
|
|
|
or the standard output (file descriptor 1) if
|
|
<I>n</I>
|
|
|
|
is not specified. If the file does not exist it is created.
|
|
<P>
|
|
|
|
The general format for appending output is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B>>></B><I>word</I>
|
|
</DL>
|
|
|
|
<A NAME="lbBM"> </A>
|
|
<H4>Redirecting Standard Output and Standard Error</H4>
|
|
|
|
This construct allows both the
|
|
standard output (file descriptor 1) and
|
|
the standard error output (file descriptor 2)
|
|
to be redirected to the file whose name is the
|
|
expansion of
|
|
<I>word</I>.
|
|
|
|
<P>
|
|
|
|
There are two formats for redirecting standard output and
|
|
standard error:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>&></B><I>word</I>
|
|
</DL>
|
|
|
|
and
|
|
<DL COMPACT><DT><DD>
|
|
<B>>&</B><I>word</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
Of the two forms, the first is preferred.
|
|
This is semantically equivalent to
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>></B><I>word</I> 2<B>>&</B>1
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
When using the second form, <I>word</I> may not expand to a number or
|
|
<B>-</B>. If it does, other redirection operators apply
|
|
(see <B>Duplicating File Descriptors</B> below) for compatibility
|
|
reasons.
|
|
<A NAME="lbBN"> </A>
|
|
<H4>Appending Standard Output and Standard Error</H4>
|
|
|
|
This construct allows both the
|
|
standard output (file descriptor 1) and
|
|
the standard error output (file descriptor 2)
|
|
to be appended to the file whose name is the
|
|
expansion of
|
|
<I>word</I>.
|
|
|
|
<P>
|
|
|
|
The format for appending standard output and standard error is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>&>></B><I>word</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
This is semantically equivalent to
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>>></B><I>word</I> 2<B>>&</B>1
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
(see <B>Duplicating File Descriptors</B> below).
|
|
<A NAME="lbBO"> </A>
|
|
<H4>Here Documents</H4>
|
|
|
|
This type of redirection instructs the shell to read input from the
|
|
current source until a line containing only
|
|
<I>delimiter</I>
|
|
|
|
(with no trailing blanks)
|
|
is seen. All of
|
|
the lines read up to that point are then used as the standard
|
|
input (or file descriptor <I>n</I> if <I>n</I> is specified) for a command.
|
|
<P>
|
|
|
|
The format of here-documents is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<PRE>
|
|
[<I>n</I>]<B><<</B>[<B>-</B>]<I>word</I>
|
|
<I>here-document</I>
|
|
<I>delimiter</I>
|
|
</PRE>
|
|
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
No parameter and variable expansion, command substitution,
|
|
arithmetic expansion, or pathname expansion is performed on
|
|
<I>word</I>.
|
|
|
|
If any part of
|
|
<I>word</I>
|
|
|
|
is quoted, the
|
|
<I>delimiter</I>
|
|
|
|
is the result of quote removal on
|
|
<I>word</I>,
|
|
|
|
and the lines in the here-document are not expanded.
|
|
If <I>word</I> is unquoted,
|
|
all lines of the here-document are subjected to
|
|
parameter expansion, command substitution, and arithmetic expansion,
|
|
the character sequence
|
|
<B>\<newline></B>
|
|
|
|
is ignored, and
|
|
<B>\</B>
|
|
|
|
must be used to quote the characters
|
|
<B>\</B>,
|
|
|
|
<B>$</B>,
|
|
|
|
and
|
|
<B>`</B>.
|
|
|
|
<P>
|
|
|
|
If the redirection operator is
|
|
<B><<-</B>,
|
|
|
|
then all leading tab characters are stripped from input lines and the
|
|
line containing
|
|
<I>delimiter</I>.
|
|
|
|
This allows
|
|
here-documents within shell scripts to be indented in a
|
|
natural fashion.
|
|
<A NAME="lbBP"> </A>
|
|
<H4>Here Strings</H4>
|
|
|
|
A variant of here documents, the format is:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<PRE>
|
|
[<I>n</I>]<B><<<</B><I>word</I>
|
|
</PRE>
|
|
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
The <I>word</I> undergoes
|
|
tilde expansion, parameter and variable expansion,
|
|
command substitution, arithmetic expansion, and quote removal.
|
|
Pathname expansion and word splitting are not performed.
|
|
The result is supplied as a single string, with a newline appended,
|
|
to the command on its
|
|
standard input (or file descriptor <I>n</I> if <I>n</I> is specified).
|
|
<A NAME="lbBQ"> </A>
|
|
<H4>Duplicating File Descriptors</H4>
|
|
|
|
The redirection operator
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B><&</B><I>word</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
is used to duplicate input file descriptors.
|
|
If
|
|
<I>word</I>
|
|
|
|
expands to one or more digits, the file descriptor denoted by
|
|
<I>n</I>
|
|
|
|
is made to be a copy of that file descriptor.
|
|
If the digits in
|
|
<I>word</I>
|
|
|
|
do not specify a file descriptor open for input, a redirection error occurs.
|
|
If
|
|
<I>word</I>
|
|
|
|
evaluates to
|
|
<B>-</B>,
|
|
|
|
file descriptor
|
|
<I>n</I>
|
|
|
|
is closed. If
|
|
<I>n</I>
|
|
|
|
is not specified, the standard input (file descriptor 0) is used.
|
|
<P>
|
|
|
|
The operator
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B>>&</B><I>word</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
is used similarly to duplicate output file descriptors. If
|
|
<I>n</I>
|
|
|
|
is not specified, the standard output (file descriptor 1) is used.
|
|
If the digits in
|
|
<I>word</I>
|
|
|
|
do not specify a file descriptor open for output, a redirection error occurs.
|
|
If
|
|
<I>word</I>
|
|
|
|
evaluates to
|
|
<B>-</B>,
|
|
|
|
file descriptor
|
|
<I>n</I>
|
|
|
|
is closed.
|
|
As a special case, if <I>n</I> is omitted, and <I>word</I> does not
|
|
expand to one or more digits or <B>-</B>, the standard output and standard
|
|
error are redirected as described previously.
|
|
<A NAME="lbBR"> </A>
|
|
<H4>Moving File Descriptors</H4>
|
|
|
|
The redirection operator
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B><&</B><I>digit</I><B>-</B>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
moves the file descriptor <I>digit</I> to file descriptor
|
|
<I>n</I>,
|
|
|
|
or the standard input (file descriptor 0) if <I>n</I> is not specified.
|
|
<I>digit</I> is closed after being duplicated to <I>n</I>.
|
|
<P>
|
|
|
|
Similarly, the redirection operator
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B>>&</B><I>digit</I><B>-</B>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
moves the file descriptor <I>digit</I> to file descriptor
|
|
<I>n</I>,
|
|
|
|
or the standard output (file descriptor 1) if <I>n</I> is not specified.
|
|
<A NAME="lbBS"> </A>
|
|
<H4>Opening File Descriptors for Reading and Writing</H4>
|
|
|
|
The redirection operator
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[<I>n</I>]<B><></B><I>word</I>
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
causes the file whose name is the expansion of
|
|
<I>word</I>
|
|
|
|
to be opened for both reading and writing on file descriptor
|
|
<I>n</I>,
|
|
|
|
or on file descriptor 0 if
|
|
<I>n</I>
|
|
|
|
is not specified. If the file does not exist, it is created.
|
|
<A NAME="lbBT"> </A>
|
|
<H3>ALIASES</H3>
|
|
|
|
<I>Aliases</I> allow a string to be substituted for a word when it is used
|
|
as the first word of a simple command.
|
|
The shell maintains a list of aliases that may be set and unset with the
|
|
<B>alias</B>
|
|
|
|
and
|
|
<B>unalias</B>
|
|
|
|
builtin commands (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
The first word of each simple command, if unquoted,
|
|
is checked to see if it has an
|
|
alias. If so, that word is replaced by the text of the alias.
|
|
The characters <B>/</B>, <B>$</B>, <B>`</B>, and <B>=</B> and
|
|
any of the shell <I>metacharacters</I> or quoting characters
|
|
listed above may not appear in an alias name.
|
|
The replacement text may contain any valid shell input,
|
|
including shell metacharacters.
|
|
The first word of the replacement text is tested
|
|
for aliases, but a word that is identical to an alias being expanded
|
|
is not expanded a second time.
|
|
This means that one may alias
|
|
<B>ls</B>
|
|
|
|
to
|
|
<B>ls -F</B>,
|
|
|
|
for instance, and
|
|
<B>bash</B>
|
|
|
|
does not try to recursively expand the replacement text.
|
|
If the last character of the alias value is a
|
|
<I>blank</I>,
|
|
|
|
then the next command
|
|
word following the alias is also checked for alias expansion.
|
|
<P>
|
|
|
|
Aliases are created and listed with the
|
|
<B>alias</B>
|
|
|
|
command, and removed with the
|
|
<B>unalias</B>
|
|
|
|
command.
|
|
<P>
|
|
|
|
There is no mechanism for using arguments in the replacement text.
|
|
If arguments are needed, use a shell function (see
|
|
<FONT SIZE=-1><B>FUNCTIONS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<P>
|
|
|
|
Aliases are not expanded when the shell is not interactive, unless
|
|
the
|
|
<B>expand_aliases</B>
|
|
|
|
shell option is set using
|
|
<B>shopt</B>
|
|
|
|
(see the description of
|
|
<B>shopt</B>
|
|
|
|
under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B></FONT>
|
|
below).
|
|
<P>
|
|
|
|
The rules concerning the definition and use of aliases are
|
|
somewhat confusing.
|
|
<B>Bash</B>
|
|
|
|
always reads at least one complete line of input,
|
|
and all lines that make up a compound command,
|
|
before executing any of the commands on that line or the compound command.
|
|
Aliases are expanded when a
|
|
command is read, not when it is executed. Therefore, an
|
|
alias definition appearing on the same line as another
|
|
command does not take effect until the next line of input is read.
|
|
The commands following the alias definition
|
|
on that line are not affected by the new alias.
|
|
This behavior is also an issue when functions are executed.
|
|
Aliases are expanded when a function definition is read,
|
|
not when the function is executed, because a function definition
|
|
is itself a command. As a consequence, aliases
|
|
defined in a function are not available until after that
|
|
function is executed. To be safe, always put
|
|
alias definitions on a separate line, and do not use
|
|
<B>alias</B>
|
|
|
|
in compound commands.
|
|
<P>
|
|
|
|
For almost every purpose, aliases are superseded by
|
|
shell functions.
|
|
<A NAME="lbBU"> </A>
|
|
<H3>FUNCTIONS</H3>
|
|
|
|
A shell function, defined as described above under
|
|
<FONT SIZE=-1><B>SHELL GRAMMAR</B>,
|
|
|
|
</FONT>
|
|
stores a series of commands for later execution.
|
|
When the name of a shell function is used as a simple command name,
|
|
the list of commands associated with that function name is executed.
|
|
Functions are executed in the context of the
|
|
current shell; no new process is created to interpret
|
|
them (contrast this with the execution of a shell script).
|
|
When a function is executed, the arguments to the
|
|
function become the positional parameters
|
|
during its execution.
|
|
The special parameter
|
|
<B>#</B>
|
|
|
|
is updated to reflect the change. Special parameter <B>0</B>
|
|
is unchanged.
|
|
The first element of the
|
|
<FONT SIZE=-1><B>FUNCNAME</B>
|
|
|
|
</FONT>
|
|
variable is set to the name of the function while the function
|
|
is executing.
|
|
<P>
|
|
|
|
All other aspects of the shell execution
|
|
environment are identical between a function and its caller
|
|
with these exceptions: the
|
|
<FONT SIZE=-1><B>DEBUG</B>
|
|
|
|
</FONT>
|
|
and
|
|
<B>RETURN</B>
|
|
|
|
traps (see the description of the
|
|
<B>trap</B>
|
|
|
|
builtin under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below) are not inherited unless the function has been given the
|
|
<B>trace</B> attribute (see the description of the
|
|
<FONT SIZE=-1><B>declare</B>
|
|
|
|
</FONT>
|
|
builtin below) or the
|
|
<B>-o functrace</B> shell option has been enabled with
|
|
the <B>set</B> builtin
|
|
(in which case all functions inherit the <B>DEBUG</B> and <B>RETURN</B> traps),
|
|
and the
|
|
<FONT SIZE=-1><B>ERR</B>
|
|
|
|
</FONT>
|
|
trap is not inherited unless the <B>-o errtrace</B> shell option has
|
|
been enabled.
|
|
<P>
|
|
|
|
Variables local to the function may be declared with the
|
|
<B>local</B>
|
|
|
|
builtin command (<I>local variables</I>).
|
|
Ordinarily, variables and their values
|
|
are shared between the function and its caller.
|
|
If a variable is declared <B>local</B>, the variable's visible scope
|
|
is restricted to that function and its children (including the functions
|
|
it calls).
|
|
<P>
|
|
|
|
In the following description, the <I>current scope</I> is a currently-
|
|
executing function.
|
|
Previous scopes consist of that function's caller and so on,
|
|
back to the "global" scope, where the shell is not executing
|
|
any shell function.
|
|
Consequently, a local variable at the current scope is a variable
|
|
declared using the <B>local</B> or <B>declare</B> builtins in the
|
|
function that is currently executing.
|
|
<P>
|
|
|
|
Local variables "shadow" variables with the same name declared at
|
|
previous scopes.
|
|
For instance, a local variable declared in a function
|
|
hides a global variable of the same name: references and assignments
|
|
refer to the local variable, leaving the global variable unmodified.
|
|
When the function returns, the global variable is once again visible.
|
|
<P>
|
|
|
|
The shell uses <I>dynamic scoping</I> to control a variable's visibility
|
|
within functions.
|
|
With dynamic scoping, visible variables and their values
|
|
are a result of the sequence of function calls that caused execution
|
|
to reach the current function.
|
|
The value of a variable that a function sees depends
|
|
on its value within its caller, if any, whether that caller is
|
|
the "global" scope or another shell function.
|
|
This is also the value that a local variable
|
|
declaration "shadows", and the value that is restored when the function
|
|
returns.
|
|
<P>
|
|
|
|
For example, if a variable <I>var</I> is declared as local in function
|
|
<I>func1</I>, and <I>func1</I> calls another function <I>func2</I>,
|
|
references to <I>var</I> made from within <I>func2</I> will resolve to the
|
|
local variable <I>var</I> from <I>func1</I>, shadowing any global variable
|
|
named <I>var</I>.
|
|
<P>
|
|
|
|
The <B>unset</B> builtin also acts using the same dynamic scope: if a
|
|
variable is local to the current scope, <B>unset</B> will unset it;
|
|
otherwise the unset will refer to the variable found in any calling scope
|
|
as described above.
|
|
If a variable at the current local scope is unset, it will remain so
|
|
(appearing as unset)
|
|
until it is reset in that scope or until the function returns.
|
|
Once the function returns, any instance of the variable at a previous
|
|
scope will become visible.
|
|
If the unset acts on a variable at a previous scope, any instance of a
|
|
variable with that name that had been shadowed will become visible
|
|
(see below how the <B>localvar_unset</B> shell option changes this behavior).
|
|
<P>
|
|
|
|
The <B>FUNCNEST</B> variable, if set to a numeric value greater
|
|
than 0, defines a maximum function nesting level. Function
|
|
invocations that exceed the limit cause the entire command to
|
|
abort.
|
|
<P>
|
|
|
|
If the builtin command
|
|
<B>return</B>
|
|
|
|
is executed in a function, the function completes and
|
|
execution resumes with the next command after the function
|
|
call.
|
|
Any command associated with the <B>RETURN</B> trap is executed
|
|
before execution resumes.
|
|
When a function completes, the values of the
|
|
positional parameters and the special parameter
|
|
<B>#</B>
|
|
|
|
are restored to the values they had prior to the function's
|
|
execution.
|
|
<P>
|
|
|
|
Function names and definitions may be listed with the
|
|
<B>-f</B>
|
|
|
|
option to the
|
|
<B>declare</B>
|
|
|
|
or
|
|
<B>typeset</B>
|
|
|
|
builtin commands. The
|
|
<B>-F</B>
|
|
|
|
option to
|
|
<B>declare</B>
|
|
|
|
or
|
|
<B>typeset</B>
|
|
|
|
will list the function names only
|
|
(and optionally the source file and line number, if the <B>extdebug</B>
|
|
shell option is enabled).
|
|
Functions may be exported so that child shell processes
|
|
(those created when executing a separate shell invocation)
|
|
automatically have them defined with the
|
|
<B>-f</B>
|
|
|
|
option to the
|
|
<B>export</B>
|
|
|
|
builtin.
|
|
A function definition may be deleted using the <B>-f</B> option to
|
|
the
|
|
<B>unset</B>
|
|
|
|
builtin.
|
|
<P>
|
|
|
|
Functions may be recursive.
|
|
The <B>FUNCNEST</B> variable may be used to limit the depth of the
|
|
function call stack and restrict the number of function invocations.
|
|
By default, no limit is imposed on the number of recursive calls.
|
|
<A NAME="lbBV"> </A>
|
|
<H3>ARITHMETIC EVALUATION</H3>
|
|
|
|
The shell allows arithmetic expressions to be evaluated, under
|
|
certain circumstances (see the <B>let</B> and <B>declare</B> builtin
|
|
commands, the <B>((</B> compound command, and <B>Arithmetic Expansion</B>).
|
|
Evaluation is done in fixed-width integers with no check for overflow,
|
|
though division by 0 is trapped and flagged as an error.
|
|
The operators and their precedence, associativity, and values
|
|
are the same as in the C language.
|
|
The following list of operators is grouped into levels of
|
|
equal-precedence operators.
|
|
The levels are listed in order of decreasing precedence.
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B></B><I>id</I>++ <I>id</I>--
|
|
|
|
<DD>
|
|
variable post-increment and post-decrement
|
|
<DT><B>- +</B>
|
|
|
|
<DD>
|
|
unary minus and plus
|
|
<DT><B>++</B><I>id</I> --<I>id</I>
|
|
|
|
<DD>
|
|
variable pre-increment and pre-decrement
|
|
<DT><B>! ~</B>
|
|
|
|
<DD>
|
|
logical and bitwise negation
|
|
<DT><B>**</B>
|
|
|
|
<DD>
|
|
exponentiation
|
|
<DT><B>* / %</B>
|
|
|
|
<DD>
|
|
multiplication, division, remainder
|
|
<DT><B>+ -</B>
|
|
|
|
<DD>
|
|
addition, subtraction
|
|
<DT><B><< >></B>
|
|
|
|
<DD>
|
|
left and right bitwise shifts
|
|
<DT><B><= >= < ></B>
|
|
|
|
<DD>
|
|
comparison
|
|
<DT><B>== !=</B>
|
|
|
|
<DD>
|
|
equality and inequality
|
|
<DT><B>&</B>
|
|
|
|
<DD>
|
|
bitwise AND
|
|
<DT><B>^</B>
|
|
|
|
<DD>
|
|
bitwise exclusive OR
|
|
<DT><B>|</B>
|
|
|
|
<DD>
|
|
bitwise OR
|
|
<DT><B>&&</B>
|
|
|
|
<DD>
|
|
logical AND
|
|
<DT><B>||</B>
|
|
|
|
<DD>
|
|
logical OR
|
|
<DT><B></B><I>expr</I>?<I>expr</I>:<I>expr</I>
|
|
|
|
<DD>
|
|
conditional operator
|
|
<DT><B>= *= /= %= += -= <<= >>= &= ^= |=</B>
|
|
|
|
<DD>
|
|
assignment
|
|
<DT><B></B><I>expr1</I> , <I>expr2</I>
|
|
|
|
<DD>
|
|
comma
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
Shell variables are allowed as operands; parameter expansion is
|
|
performed before the expression is evaluated.
|
|
Within an expression, shell variables may also be referenced by name
|
|
without using the parameter expansion syntax.
|
|
A shell variable that is null or unset evaluates to 0 when referenced
|
|
by name without using the parameter expansion syntax.
|
|
The value of a variable is evaluated as an arithmetic expression
|
|
when it is referenced, or when a variable which has been given the
|
|
<I>integer</I> attribute using <B>declare -i</B> is assigned a value.
|
|
A null value evaluates to 0.
|
|
A shell variable need not have its <I>integer</I> attribute
|
|
turned on to be used in an expression.
|
|
<P>
|
|
|
|
Integer constants follow the C language definition, without suffixes or
|
|
character constants.
|
|
Constants with a leading 0 are interpreted as octal numbers.
|
|
A leading 0x or 0X denotes hexadecimal.
|
|
Otherwise, numbers take the form [<I>base#</I>]n, where the optional <I>base</I>
|
|
is a decimal number between 2 and 64 representing the arithmetic
|
|
base, and <I>n</I> is a number in that base.
|
|
If <I>base#</I> is omitted, then base 10 is used.
|
|
When specifying <I>n</I>,
|
|
if a non-digit is required,
|
|
the digits greater than 9 are represented by the lowercase letters,
|
|
the uppercase letters, @, and _, in that order.
|
|
If <I>base</I> is less than or equal to 36, lowercase and uppercase
|
|
letters may be used interchangeably to represent numbers between 10
|
|
and 35.
|
|
<P>
|
|
|
|
Operators are evaluated in order of precedence. Sub-expressions in
|
|
parentheses are evaluated first and may override the precedence
|
|
rules above.
|
|
<A NAME="lbBW"> </A>
|
|
<H3>CONDITIONAL EXPRESSIONS</H3>
|
|
|
|
Conditional expressions are used by the <B>[[</B> compound command and
|
|
the <B>test</B> and <B>[</B> builtin commands to test file attributes
|
|
and perform string and arithmetic comparisons.
|
|
The <B>test</B> and <B>[</B> commands determine their behavior based on
|
|
the number of arguments; see the descriptions of those commands for any
|
|
other command-specific actions.
|
|
<P>
|
|
|
|
Expressions are formed from the following unary or binary primaries.
|
|
<B>Bash</B> handles several filenames specially when they are used in
|
|
expressions.
|
|
If the operating system on which <B>bash</B> is running provides these
|
|
special files, bash will use them; otherwise it will emulate them
|
|
internally with this behavior:
|
|
If any <I>file</I> argument to one of the primaries is of the form
|
|
<I>/dev/fd/n</I>, then file descriptor <I>n</I> is checked.
|
|
If the <I>file</I> argument to one of the primaries is one of
|
|
<I>/dev/stdin</I>, <I>/dev/stdout</I>, or <I>/dev/stderr</I>, file
|
|
descriptor 0, 1, or 2, respectively, is checked.
|
|
<P>
|
|
|
|
Unless otherwise specified, primaries that operate on files follow symbolic
|
|
links and operate on the target of the link, rather than the link itself.
|
|
<P>
|
|
|
|
|
|
When used with <B>[[</B>, the <B><</B> and <B>></B> operators sort
|
|
lexicographically using the current locale.
|
|
The <B>test</B> command sorts using ASCII ordering.
|
|
<P>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-a </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists.
|
|
<DT><B>-b </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a block special file.
|
|
<DT><B>-c </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a character special file.
|
|
<DT><B>-d </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a directory.
|
|
<DT><B>-e </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists.
|
|
<DT><B>-f </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a regular file.
|
|
<DT><B>-g </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is set-group-id.
|
|
<DT><B>-h </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a symbolic link.
|
|
<DT><B>-k </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and its ``sticky'' bit is set.
|
|
<DT><B>-p </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a named pipe (FIFO).
|
|
<DT><B>-r </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is readable.
|
|
<DT><B>-s </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and has a size greater than zero.
|
|
<DT><B>-t </B><I>fd</I>
|
|
|
|
<DD>
|
|
True if file descriptor
|
|
<I>fd</I>
|
|
|
|
is open and refers to a terminal.
|
|
<DT><B>-u </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and its set-user-id bit is set.
|
|
<DT><B>-w </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is writable.
|
|
<DT><B>-x </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is executable.
|
|
<DT><B>-G </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is owned by the effective group id.
|
|
<DT><B>-L </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a symbolic link.
|
|
<DT><B>-N </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and has been modified since it was last read.
|
|
<DT><B>-O </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is owned by the effective user id.
|
|
<DT><B>-S </B><I>file</I>
|
|
|
|
<DD>
|
|
True if <I>file</I> exists and is a socket.
|
|
<DT><I>file1</I> <B>-ef</B> <I>file2</I><DD>
|
|
True if <I>file1</I> and <I>file2</I> refer to the same device and
|
|
inode numbers.
|
|
<DT><I>file1</I> -<B>nt</B> <I>file2</I><DD>
|
|
True if <I>file1</I> is newer (according to modification date) than <I>file2</I>,
|
|
or if <I>file1</I> exists and file2 does not.
|
|
<DT><I>file1</I> -<B>ot</B> <I>file2</I><DD>
|
|
True if <I>file1</I> is older than <I>file2</I>, or if <I>file2</I> exists
|
|
and <I>file1</I> does not.
|
|
<DT><B>-o </B><I>optname</I>
|
|
|
|
<DD>
|
|
True if the shell option
|
|
<I>optname</I>
|
|
|
|
is enabled.
|
|
See the list of options under the description of the
|
|
<B>-o</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin below.
|
|
<DT><B>-v </B><I>varname</I>
|
|
|
|
<DD>
|
|
True if the shell variable
|
|
<I>varname</I>
|
|
|
|
is set (has been assigned a value).
|
|
<DT><B>-R </B><I>varname</I>
|
|
|
|
<DD>
|
|
True if the shell variable
|
|
<I>varname</I>
|
|
|
|
is set and is a name reference.
|
|
<DT><B>-z </B><I>string</I>
|
|
|
|
<DD>
|
|
True if the length of <I>string</I> is zero.
|
|
<DT><I>string</I><DD>
|
|
|
|
<DT><B>-n </B><I>string</I>
|
|
|
|
<DD>
|
|
|
|
True if the length of
|
|
<I>string</I>
|
|
|
|
is non-zero.
|
|
<DT><I>string1</I> <B>==</B> <I>string2</I><DD>
|
|
|
|
<DT><I>string1</I> <B>=</B> <I>string2</I><DD>
|
|
|
|
True if the strings are equal. <B>=</B> should be used
|
|
with the <B>test</B> command for POSIX conformance.
|
|
When used with the <B>[[</B> command, this performs pattern matching as
|
|
described above (<B>Compound Commands</B>).
|
|
<DT><I>string1</I> <B>!=</B> <I>string2</I><DD>
|
|
True if the strings are not equal.
|
|
<DT><I>string1</I> <B><</B> <I>string2</I><DD>
|
|
True if <I>string1</I> sorts before <I>string2</I> lexicographically.
|
|
<DT><I>string1</I> <B>></B> <I>string2</I><DD>
|
|
True if <I>string1</I> sorts after <I>string2</I> lexicographically.
|
|
<DT><I>arg1</I> <B>OP</B> <I>arg2</I>
|
|
|
|
<DD>
|
|
<FONT SIZE=-1><B>OP</B>
|
|
|
|
</FONT>
|
|
is one of
|
|
<B>-eq</B>,
|
|
|
|
<B>-ne</B>,
|
|
|
|
<B>-lt</B>,
|
|
|
|
<B>-le</B>,
|
|
|
|
<B>-gt</B>,
|
|
|
|
or
|
|
<B>-ge</B>.
|
|
|
|
These arithmetic binary operators return true if <I>arg1</I>
|
|
is equal to, not equal to, less than, less than or equal to,
|
|
greater than, or greater than or equal to <I>arg2</I>, respectively.
|
|
<I>Arg1</I>
|
|
|
|
and
|
|
<I>arg2</I>
|
|
|
|
may be positive or negative integers.
|
|
When used with the <B>[[</B> command,
|
|
<I>Arg1</I>
|
|
|
|
and
|
|
<I>Arg2</I>
|
|
|
|
are evaluated as arithmetic expressions (see
|
|
<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>
|
|
|
|
</FONT>
|
|
above).
|
|
|
|
</DL>
|
|
<A NAME="lbBX"> </A>
|
|
<H3>SIMPLE COMMAND EXPANSION</H3>
|
|
|
|
When a simple command is executed, the shell performs the following
|
|
expansions, assignments, and redirections, from left to right, in
|
|
the following order.
|
|
<DL COMPACT>
|
|
<DT>1.<DD>
|
|
The words that the parser has marked as variable assignments (those
|
|
preceding the command name) and redirections are saved for later
|
|
processing.
|
|
<DT>2.<DD>
|
|
The words that are not variable assignments or redirections are
|
|
expanded. If any words remain after expansion, the first word
|
|
is taken to be the name of the command and the remaining words are
|
|
the arguments.
|
|
<DT>3.<DD>
|
|
Redirections are performed as described above under
|
|
<FONT SIZE=-1><B>REDIRECTION</B>.
|
|
|
|
</FONT>
|
|
<DT>4.<DD>
|
|
The text after the <B>=</B> in each variable assignment undergoes tilde
|
|
expansion, parameter expansion, command substitution, arithmetic expansion,
|
|
and quote removal before being assigned to the variable.
|
|
</DL>
|
|
<P>
|
|
|
|
If no command name results, the variable assignments affect the current
|
|
shell environment.
|
|
In the case of such a command (one that consists only of assignment
|
|
statements and redirections), assignment statements are performed before
|
|
redirections.
|
|
Otherwise, the variables are added to the environment
|
|
of the executed command and do not affect the current shell environment.
|
|
If any of the assignments attempts to assign a value to a readonly variable,
|
|
an error occurs, and the command exits with a non-zero status.
|
|
<P>
|
|
|
|
If no command name results, redirections are performed, but do not
|
|
affect the current shell environment. A redirection error causes the
|
|
command to exit with a non-zero status.
|
|
<P>
|
|
|
|
If there is a command name left after expansion, execution proceeds as
|
|
described below. Otherwise, the command exits. If one of the expansions
|
|
contained a command substitution, the exit status of the command is
|
|
the exit status of the last command substitution performed. If there
|
|
were no command substitutions, the command exits with a status of zero.
|
|
<A NAME="lbBY"> </A>
|
|
<H3>COMMAND EXECUTION</H3>
|
|
|
|
After a command has been split into words, if it results in a
|
|
simple command and an optional list of arguments, the following
|
|
actions are taken.
|
|
<P>
|
|
|
|
If the command name contains no slashes, the shell attempts to
|
|
locate it. If there exists a shell function by that name, that
|
|
function is invoked as described above in
|
|
<FONT SIZE=-1><B>FUNCTIONS</B>.
|
|
|
|
</FONT>
|
|
If the name does not match a function, the shell searches for
|
|
it in the list of shell builtins. If a match is found, that
|
|
builtin is invoked.
|
|
<P>
|
|
|
|
If the name is neither a shell function nor a builtin,
|
|
and contains no slashes,
|
|
<B>bash</B>
|
|
|
|
searches each element of the
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
for a directory containing an executable file by that name.
|
|
<B>Bash</B>
|
|
|
|
uses a hash table to remember the full pathnames of executable
|
|
files (see
|
|
<B>hash</B>
|
|
|
|
under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
A full search of the directories in
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
is performed only if the command is not found in the hash table.
|
|
If the search is unsuccessful, the shell searches for a defined shell
|
|
function named <B>command_not_found_handle</B>.
|
|
If that function exists, it is invoked in a separate execution environment
|
|
with the original command and
|
|
the original command's arguments as its arguments, and the function's
|
|
exit status becomes the exit status of that subshell.
|
|
If that function is not defined, the shell prints an error
|
|
message and returns an exit status of 127.
|
|
<P>
|
|
|
|
If the search is successful, or if the command name contains
|
|
one or more slashes, the shell executes the named program in a
|
|
separate execution environment.
|
|
Argument 0 is set to the name given, and the remaining arguments
|
|
to the command are set to the arguments given, if any.
|
|
<P>
|
|
|
|
If this execution fails because the file is not in executable
|
|
format, and the file is not a directory, it is assumed to be
|
|
a <I>shell script</I>, a file
|
|
containing shell commands, and the shell creates a
|
|
new instance of itself
|
|
to execute it.
|
|
This subshell reinitializes itself, so
|
|
that the effect is as if a new shell had been invoked
|
|
to handle the script, with the exception that the locations of
|
|
commands remembered by the parent (see
|
|
<B>hash</B>
|
|
|
|
below under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>)</FONT>
|
|
are retained by the child.
|
|
<P>
|
|
|
|
If the program is a file beginning with
|
|
<B>#!</B>,
|
|
|
|
the remainder of the first line specifies an interpreter
|
|
for the program. The shell executes the
|
|
specified interpreter on operating systems that do not
|
|
handle this executable format themselves. The arguments to the
|
|
interpreter consist of a single optional argument following the
|
|
interpreter name on the first line of the program, followed
|
|
by the name of the program, followed by the command
|
|
arguments, if any.
|
|
<A NAME="lbBZ"> </A>
|
|
<H3>COMMAND EXECUTION ENVIRONMENT</H3>
|
|
|
|
The shell has an <I>execution environment</I>, which consists of the
|
|
following:
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
open files inherited by the shell at invocation, as modified by
|
|
redirections supplied to the <B>exec</B> builtin
|
|
<DT>*<DD>
|
|
the current working directory as set by <B>cd</B>, <B>pushd</B>, or
|
|
<B>popd</B>, or inherited by the shell at invocation
|
|
<DT>*<DD>
|
|
the file creation mode mask as set by <B>umask</B> or inherited from
|
|
the shell's parent
|
|
<DT>*<DD>
|
|
current traps set by <B>trap</B>
|
|
<DT>*<DD>
|
|
shell parameters that are set by variable assignment or with <B>set</B>
|
|
or inherited from the shell's parent in the environment
|
|
<DT>*<DD>
|
|
shell functions defined during execution or inherited from the shell's
|
|
parent in the environment
|
|
<DT>*<DD>
|
|
options enabled at invocation (either by default or with command-line
|
|
arguments) or by <B>set</B>
|
|
<DT>*<DD>
|
|
options enabled by <B>shopt</B>
|
|
<DT>*<DD>
|
|
shell aliases defined with <B>alias</B>
|
|
<DT>*<DD>
|
|
various process IDs, including those of background jobs, the value
|
|
of <B>$$</B>, and the value of
|
|
<FONT SIZE=-1><B>PPID</B>
|
|
|
|
</FONT>
|
|
</DL>
|
|
<P>
|
|
|
|
When a simple command other than a builtin or shell function
|
|
is to be executed, it
|
|
is invoked in a separate execution environment that consists of
|
|
the following.
|
|
Unless otherwise noted, the values are inherited from the shell.
|
|
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
the shell's open files, plus any modifications and additions specified
|
|
by redirections to the command
|
|
<DT>*<DD>
|
|
the current working directory
|
|
<DT>*<DD>
|
|
the file creation mode mask
|
|
<DT>*<DD>
|
|
shell variables and functions marked for export, along with variables
|
|
exported for the command, passed in the environment
|
|
<DT>*<DD>
|
|
traps caught by the shell are reset to the values inherited from the
|
|
shell's parent, and traps ignored by the shell are ignored
|
|
</DL>
|
|
<P>
|
|
|
|
A command invoked in this separate environment cannot affect the
|
|
shell's execution environment.
|
|
<P>
|
|
|
|
A <I>subshell</I> is a copy of the shell process.
|
|
<P>
|
|
|
|
Command substitution, commands grouped with parentheses,
|
|
and asynchronous commands are invoked in a
|
|
subshell environment that is a duplicate of the shell environment,
|
|
except that traps caught by the shell are reset to the values
|
|
that the shell inherited from its parent at invocation. Builtin
|
|
commands that are invoked as part of a pipeline are also executed in a
|
|
subshell environment. Changes made to the subshell environment
|
|
cannot affect the shell's execution environment.
|
|
<P>
|
|
|
|
Subshells spawned to execute command substitutions inherit the value of
|
|
the <B>-e</B> option from the parent shell. When not in <I>posix mode</I>,
|
|
<B>bash</B> clears the <B>-e</B> option in such subshells.
|
|
<P>
|
|
|
|
If a command is followed by a <B>&</B> and job control is not active, the
|
|
default standard input for the command is the empty file <I>/dev/null</I>.
|
|
Otherwise, the invoked command inherits the file descriptors of the calling
|
|
shell as modified by redirections.
|
|
<A NAME="lbCA"> </A>
|
|
<H3>ENVIRONMENT</H3>
|
|
|
|
When a program is invoked it is given an array of strings
|
|
called the
|
|
<I>environment</I>.
|
|
|
|
This is a list of
|
|
<I>name</I>-<I>value</I> pairs, of the form
|
|
<I>name</I>=value.
|
|
|
|
<P>
|
|
|
|
The shell provides several ways to manipulate the environment.
|
|
On invocation, the shell scans its own environment and
|
|
creates a parameter for each name found, automatically marking
|
|
it for
|
|
<I>export</I>
|
|
|
|
to child processes. Executed commands inherit the environment.
|
|
The
|
|
<B>export</B>
|
|
|
|
and
|
|
<B>declare -x</B>
|
|
|
|
commands allow parameters and functions to be added to and
|
|
deleted from the environment. If the value of a parameter
|
|
in the environment is modified, the new value becomes part
|
|
of the environment, replacing the old. The environment
|
|
inherited by any executed command consists of the shell's
|
|
initial environment, whose values may be modified in the shell,
|
|
less any pairs removed by the
|
|
<B>unset</B>
|
|
|
|
command, plus any additions via the
|
|
<B>export</B>
|
|
|
|
and
|
|
<B>declare -x</B>
|
|
|
|
commands.
|
|
<P>
|
|
|
|
The environment for any
|
|
<I>simple command</I>
|
|
|
|
or function may be augmented temporarily by prefixing it with
|
|
parameter assignments, as described above in
|
|
<FONT SIZE=-1><B>PARAMETERS</B>.
|
|
|
|
</FONT>
|
|
These assignment statements affect only the environment seen
|
|
by that command.
|
|
<P>
|
|
|
|
If the
|
|
<B>-k</B>
|
|
|
|
option is set (see the
|
|
<B>set</B>
|
|
|
|
builtin command below), then
|
|
<I>all</I>
|
|
|
|
parameter assignments are placed in the environment for a command,
|
|
not just those that precede the command name.
|
|
<P>
|
|
|
|
When
|
|
<B>bash</B>
|
|
|
|
invokes an external command, the variable
|
|
<B>_</B>
|
|
|
|
is set to the full filename of the command and passed to that
|
|
command in its environment.
|
|
<A NAME="lbCB"> </A>
|
|
<H3>EXIT STATUS</H3>
|
|
|
|
The exit status of an executed command is the value returned by the
|
|
<I>waitpid</I> system call or equivalent function. Exit statuses
|
|
fall between 0 and 255, though, as explained below, the shell may
|
|
use values above 125 specially. Exit statuses from shell builtins and
|
|
compound commands are also limited to this range. Under certain
|
|
circumstances, the shell will use special values to indicate specific
|
|
failure modes.
|
|
<P>
|
|
|
|
For the shell's purposes, a command which exits with a
|
|
zero exit status has succeeded. An exit status of zero
|
|
indicates success. A non-zero exit status indicates failure.
|
|
When a command terminates on a fatal signal <I>N</I>, <B>bash</B> uses
|
|
the value of 128+<I>N</I> as the exit status.
|
|
<P>
|
|
|
|
If a command is not found, the child process created to
|
|
execute it returns a status of 127. If a command is found
|
|
but is not executable, the return status is 126.
|
|
<P>
|
|
|
|
If a command fails because of an error during expansion or redirection,
|
|
the exit status is greater than zero.
|
|
<P>
|
|
|
|
Shell builtin commands return a status of 0 (<I>true</I>) if
|
|
successful, and non-zero (<I>false</I>) if an error occurs
|
|
while they execute.
|
|
All builtins return an exit status of 2 to indicate incorrect usage,
|
|
generally invalid options or missing arguments.
|
|
<P>
|
|
|
|
The exit status of the last command is available in the special
|
|
parameter $?.
|
|
<P>
|
|
|
|
<B>Bash</B> itself returns the exit status of the last command
|
|
executed, unless a syntax error occurs, in which case it exits
|
|
with a non-zero value. See also the <B>exit</B> builtin
|
|
command below.
|
|
<A NAME="lbCC"> </A>
|
|
<H3>SIGNALS</H3>
|
|
|
|
When <B>bash</B> is interactive, in the absence of any traps, it ignores
|
|
<FONT SIZE=-1><B>SIGTERM</B>
|
|
|
|
</FONT>
|
|
(so that <B>kill 0</B> does not kill an interactive shell),
|
|
and
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
is caught and handled (so that the <B>wait</B> builtin is interruptible).
|
|
In all cases, <B>bash</B> ignores
|
|
<FONT SIZE=-1><B>SIGQUIT</B>.
|
|
|
|
</FONT>
|
|
If job control is in effect,
|
|
<B>bash</B>
|
|
|
|
ignores
|
|
<FONT SIZE=-1><B>SIGTTIN</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>SIGTTOU</B>,
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>SIGTSTP</B>.
|
|
|
|
</FONT>
|
|
<P>
|
|
|
|
Non-builtin commands run by <B>bash</B> have signal handlers
|
|
set to the values inherited by the shell from its parent.
|
|
When job control is not in effect, asynchronous commands
|
|
ignore
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>SIGQUIT</B>
|
|
|
|
</FONT>
|
|
in addition to these inherited handlers.
|
|
Commands run as a result of command substitution ignore the
|
|
keyboard-generated job control signals
|
|
<FONT SIZE=-1><B>SIGTTIN</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>SIGTTOU</B>,
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>SIGTSTP</B>.
|
|
|
|
</FONT>
|
|
<P>
|
|
|
|
The shell exits by default upon receipt of a
|
|
<FONT SIZE=-1><B>SIGHUP</B>.
|
|
|
|
</FONT>
|
|
Before exiting, an interactive shell resends the
|
|
<FONT SIZE=-1><B>SIGHUP</B>
|
|
|
|
</FONT>
|
|
to all jobs, running or stopped.
|
|
Stopped jobs are sent
|
|
<FONT SIZE=-1><B>SIGCONT</B>
|
|
|
|
</FONT>
|
|
to ensure that they receive the
|
|
<FONT SIZE=-1><B>SIGHUP</B>.
|
|
|
|
</FONT>
|
|
To prevent the shell from
|
|
sending the signal to a particular job, it should be removed from the
|
|
jobs table with the
|
|
<B>disown</B>
|
|
|
|
builtin (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below) or marked
|
|
to not receive
|
|
<FONT SIZE=-1><B>SIGHUP</B>
|
|
|
|
</FONT>
|
|
using
|
|
<B>disown -h</B>.
|
|
|
|
<P>
|
|
|
|
If the
|
|
<B>huponexit</B>
|
|
|
|
shell option has been set with
|
|
<B>shopt</B>,
|
|
|
|
<B>bash</B>
|
|
|
|
sends a
|
|
<FONT SIZE=-1><B>SIGHUP</B>
|
|
|
|
</FONT>
|
|
to all jobs when an interactive login shell exits.
|
|
<P>
|
|
|
|
If <B>bash</B> is waiting for a command to complete and receives a signal
|
|
for which a trap has been set, the trap will not be executed until
|
|
the command completes.
|
|
When <B>bash</B> is waiting for an asynchronous command via the <B>wait</B>
|
|
builtin, the reception of a signal for which a trap has been set will
|
|
cause the <B>wait</B> builtin to return immediately with an exit status
|
|
greater than 128, immediately after which the trap is executed.
|
|
<P>
|
|
|
|
When job control is not enabled, and <B>bash</B> is waiting for a foreground
|
|
command to complete, the shell receives keyboard-generated signals
|
|
such as
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
(usually generated by <B>^C</B>) that users commonly intend to send
|
|
to that command.
|
|
This happens because the shell and the command are in the
|
|
same process group as the terminal, and <B>^C</B> sends
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
to all processes in that process group.
|
|
<P>
|
|
|
|
When <B>bash</B> is running without job control enabled and receives
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
while waiting for a foreground command, it waits until that foreground
|
|
command terminates and then decides what to do about the
|
|
<FONT SIZE=-1><B>SIGINT</B>:
|
|
|
|
</FONT>
|
|
<DL COMPACT>
|
|
<DT>1.<DD>
|
|
If the command terminates due to the
|
|
<FONT SIZE=-1><B>SIGINT</B>,
|
|
|
|
</FONT>
|
|
<B>bash</B> concludes
|
|
that the user meant to end the entire script, and acts on the
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
(e.g., by running a
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
trap or exiting itself);
|
|
<DT>2.<DD>
|
|
If the command does not terminate due to
|
|
<FONT SIZE=-1><B>SIGINT</B>,
|
|
|
|
</FONT>
|
|
the program handled the
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
itself and did not treat it as a fatal signal.
|
|
In that case, <B>bash</B> does not treat
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
as a fatal signal, either, instead assuming that the
|
|
<FONT SIZE=-1><B>SIGINT</B>
|
|
|
|
</FONT>
|
|
was used as part of the program's normal operation
|
|
(e.g., emacs uses it to abort editing
|
|
commands) or deliberately discarded.
|
|
However, <B>bash</B> will run any
|
|
trap set on
|
|
<FONT SIZE=-1><B>SIGINT</B>,
|
|
|
|
</FONT>
|
|
as it does with any other trapped signal it
|
|
receives while it is waiting for the foreground command to
|
|
complete, for compatibility.
|
|
</DL>
|
|
<A NAME="lbCD"> </A>
|
|
<H3>JOB CONTROL</H3>
|
|
|
|
<I>Job control</I>
|
|
|
|
refers to the ability to selectively stop (<I>suspend</I>)
|
|
the execution of processes and continue (<I>resume</I>)
|
|
their execution at a later point. A user typically employs
|
|
this facility via an interactive interface supplied jointly
|
|
by the operating system kernel's terminal driver and
|
|
<B>bash</B>.
|
|
|
|
<P>
|
|
|
|
The shell associates a
|
|
<I>job</I>
|
|
|
|
with each pipeline. It keeps a table of currently executing
|
|
jobs, which may be listed with the
|
|
<B>jobs</B>
|
|
|
|
command. When
|
|
<B>bash</B>
|
|
|
|
starts a job asynchronously (in the
|
|
<I>background</I>),
|
|
|
|
it prints a line that looks like:
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
[1] 25647
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
indicating that this job is job number 1 and that the process ID
|
|
of the last process in the pipeline associated with this job is 25647.
|
|
All of the processes in a single pipeline are members of the same job.
|
|
<B>Bash</B>
|
|
|
|
uses the
|
|
<I>job</I>
|
|
|
|
abstraction as the basis for job control.
|
|
<P>
|
|
|
|
To facilitate the implementation of the user interface to job
|
|
control, the operating system maintains the notion of a <I>current terminal
|
|
process group ID</I>. Members of this process group (processes whose
|
|
process group ID is equal to the current terminal process group ID)
|
|
receive keyboard-generated signals such as
|
|
<FONT SIZE=-1><B>SIGINT</B>.
|
|
|
|
</FONT>
|
|
These processes are said to be in the
|
|
<I>foreground</I>.
|
|
|
|
<I>Background</I>
|
|
|
|
processes are those whose process group ID differs from the terminal's;
|
|
such processes are immune to keyboard-generated signals.
|
|
Only foreground processes are allowed to read from or, if the
|
|
user so specifies with <TT>stty tostop</TT>, write to the
|
|
terminal.
|
|
Background processes which attempt to read from (write to when
|
|
<TT>stty tostop</TT> is in effect) the
|
|
terminal are sent a
|
|
<FONT SIZE=-1><B>SIGTTIN (SIGTTOU)</B>
|
|
|
|
</FONT>
|
|
signal by the kernel's terminal driver,
|
|
which, unless caught, suspends the process.
|
|
<P>
|
|
|
|
If the operating system on which
|
|
<B>bash</B>
|
|
|
|
is running supports
|
|
job control,
|
|
<B>bash</B>
|
|
|
|
contains facilities to use it.
|
|
Typing the
|
|
<I>suspend</I>
|
|
|
|
character (typically
|
|
<B>^Z</B>,
|
|
|
|
Control-Z) while a process is running
|
|
causes that process to be stopped and returns control to
|
|
<B>bash</B>.
|
|
|
|
Typing the
|
|
<I>delayed suspend</I>
|
|
|
|
character (typically
|
|
<B>^Y</B>,
|
|
|
|
Control-Y) causes the process to be stopped when it
|
|
attempts to read input from the terminal, and control to
|
|
be returned to
|
|
<B>bash</B>.
|
|
|
|
The user may then manipulate the state of this job, using the
|
|
<B>bg</B>
|
|
|
|
command to continue it in the background, the
|
|
<B>fg</B>
|
|
|
|
command to continue it in the foreground, or
|
|
the
|
|
<B>kill</B>
|
|
|
|
command to kill it. A <B>^Z</B> takes effect immediately,
|
|
and has the additional side effect of causing pending output
|
|
and typeahead to be discarded.
|
|
<P>
|
|
|
|
There are a number of ways to refer to a job in the shell.
|
|
The character
|
|
<B>%</B>
|
|
|
|
introduces a job specification (<I>jobspec</I>). Job number
|
|
<I>n</I>
|
|
|
|
may be referred to as
|
|
<B>%n</B>.
|
|
|
|
A job may also be referred to using a prefix of the name used to
|
|
start it, or using a substring that appears in its command line.
|
|
For example,
|
|
<B>%ce</B>
|
|
|
|
refers to a stopped
|
|
job whose command name begins with
|
|
<B>ce</B>.
|
|
|
|
If a prefix matches more than one job,
|
|
<B>bash</B>
|
|
|
|
reports an error. Using
|
|
<B>%?ce</B>,
|
|
|
|
on the other hand, refers to any job containing the string
|
|
<B>ce</B>
|
|
|
|
in its command line. If the substring matches more than one job,
|
|
<B>bash</B>
|
|
|
|
reports an error. The symbols
|
|
<B>%%</B>
|
|
|
|
and
|
|
<B>%+</B>
|
|
|
|
refer to the shell's notion of the
|
|
<I>current job</I>,
|
|
|
|
which is the last job stopped while it was in
|
|
the foreground or started in the background.
|
|
The
|
|
<I>previous job</I>
|
|
|
|
may be referenced using
|
|
<B>%-</B>.
|
|
|
|
If there is only a single job, <B>%+</B> and <B>%-</B> can both be used
|
|
to refer to that job.
|
|
In output pertaining to jobs (e.g., the output of the
|
|
<B>jobs</B>
|
|
|
|
command), the current job is always flagged with a
|
|
<B>+</B>,
|
|
|
|
and the previous job with a
|
|
<B>-</B>.
|
|
|
|
A single % (with no accompanying job specification) also refers to the
|
|
current job.
|
|
<P>
|
|
|
|
Simply naming a job can be used to bring it into the
|
|
foreground:
|
|
<B>%1</B>
|
|
|
|
is a synonym for
|
|
<B>``fg %1''</B>,
|
|
bringing job 1 from the background into the foreground.
|
|
Similarly,
|
|
<B>``%1 &''</B>
|
|
|
|
resumes job 1 in the background, equivalent to
|
|
<B>``bg %1''</B>.
|
|
<P>
|
|
|
|
The shell learns immediately whenever a job changes state.
|
|
Normally,
|
|
<B>bash</B>
|
|
|
|
waits until it is about to print a prompt before reporting
|
|
changes in a job's status so as to not interrupt
|
|
any other output. If the
|
|
<B>-b</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin command
|
|
is enabled,
|
|
<B>bash</B>
|
|
|
|
reports such changes immediately.
|
|
Any trap on
|
|
<FONT SIZE=-1><B>SIGCHLD</B>
|
|
|
|
</FONT>
|
|
is executed for each child that exits.
|
|
<P>
|
|
|
|
If an attempt to exit
|
|
<B>bash</B>
|
|
|
|
is made while jobs are stopped (or, if the <B>checkjobs</B> shell option has
|
|
been enabled using the <B>shopt</B> builtin, running), the shell prints a
|
|
warning message, and, if the <B>checkjobs</B> option is enabled, lists the
|
|
jobs and their statuses.
|
|
The
|
|
<B>jobs</B>
|
|
|
|
command may then be used to inspect their status.
|
|
If a second attempt to exit is made without an intervening command,
|
|
the shell does not print another warning, and any stopped
|
|
jobs are terminated.
|
|
<P>
|
|
|
|
When the shell is waiting for a job or process using the <B>wait</B>
|
|
builtin, and job control is enabled, <B>wait</B> will return when the
|
|
job changes state. The <B>-f</B> option causes <B>wait</B> to wait
|
|
until the job or process terminates before returning.
|
|
<A NAME="lbCE"> </A>
|
|
<H3>PROMPTING</H3>
|
|
|
|
When executing interactively,
|
|
<B>bash</B>
|
|
|
|
displays the primary prompt
|
|
<FONT SIZE=-1><B>PS1</B>
|
|
|
|
</FONT>
|
|
when it is ready to read a command, and the secondary prompt
|
|
<FONT SIZE=-1><B>PS2</B>
|
|
|
|
</FONT>
|
|
when it needs more input to complete a command.
|
|
<B>Bash</B>
|
|
|
|
displays
|
|
<FONT SIZE=-1><B>PS0</B>
|
|
|
|
</FONT>
|
|
after it reads a command but before executing it.
|
|
<B>Bash</B>
|
|
|
|
displays
|
|
<FONT SIZE=-1><B>PS4</B>
|
|
|
|
</FONT>
|
|
as described above
|
|
before tracing each command when the <B>-x</B> option is enabled.
|
|
<B>Bash</B>
|
|
|
|
allows these prompt strings to be customized by inserting a number of
|
|
backslash-escaped special characters that are decoded as follows:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>\a</B>
|
|
|
|
<DD>
|
|
an ASCII bell character (07)
|
|
<DT><B>\d</B>
|
|
|
|
<DD>
|
|
the date in "Weekday Month Date" format (e.g., "Tue May 26")
|
|
<DT><B>\D{</B><I>format</I>}
|
|
|
|
<DD>
|
|
the <I>format</I> is passed to <I>strftime</I>(3) and the result is inserted
|
|
into the prompt string; an empty <I>format</I> results in a locale-specific
|
|
time representation. The braces are required
|
|
<DT><B>\e</B>
|
|
|
|
<DD>
|
|
an ASCII escape character (033)
|
|
<DT><B>\h</B>
|
|
|
|
<DD>
|
|
the hostname up to the first `.'
|
|
<DT><B>\H</B>
|
|
|
|
<DD>
|
|
the hostname
|
|
<DT><B>\j</B>
|
|
|
|
<DD>
|
|
the number of jobs currently managed by the shell
|
|
<DT><B>\l</B>
|
|
|
|
<DD>
|
|
the basename of the shell's terminal device name
|
|
<DT><B>\n</B>
|
|
|
|
<DD>
|
|
newline
|
|
<DT><B>\r</B>
|
|
|
|
<DD>
|
|
carriage return
|
|
<DT><B>\s</B>
|
|
|
|
<DD>
|
|
the name of the shell, the basename of
|
|
<B>$0</B>
|
|
|
|
(the portion following the final slash)
|
|
<DT><B>\t</B>
|
|
|
|
<DD>
|
|
the current time in 24-hour HH:MM:SS format
|
|
<DT><B>\T</B>
|
|
|
|
<DD>
|
|
the current time in 12-hour HH:MM:SS format
|
|
<DT><B>\@</B>
|
|
|
|
<DD>
|
|
the current time in 12-hour am/pm format
|
|
<DT><B>\A</B>
|
|
|
|
<DD>
|
|
the current time in 24-hour HH:MM format
|
|
<DT><B>\u</B>
|
|
|
|
<DD>
|
|
the username of the current user
|
|
<DT><B>\v</B>
|
|
|
|
<DD>
|
|
the version of <B>bash</B> (e.g., 2.00)
|
|
<DT><B>\V</B>
|
|
|
|
<DD>
|
|
the release of <B>bash</B>, version + patch level (e.g., 2.00.0)
|
|
<DT><B>\w</B>
|
|
|
|
<DD>
|
|
the value of the <B>PWD</B> shell variable (<B>$PWD</B>),
|
|
with
|
|
<FONT SIZE=-1><B>$HOME</B>
|
|
|
|
</FONT>
|
|
abbreviated with a tilde
|
|
(uses the value of the
|
|
<FONT SIZE=-1><B>PROMPT_DIRTRIM</B>
|
|
|
|
</FONT>
|
|
variable)
|
|
<DT><B>\W</B>
|
|
|
|
<DD>
|
|
the basename of <B>$PWD</B>,
|
|
with
|
|
<FONT SIZE=-1><B>$HOME</B>
|
|
|
|
</FONT>
|
|
abbreviated with a tilde
|
|
<DT><B>\!</B>
|
|
|
|
<DD>
|
|
the history number of this command
|
|
<DT><B>\#</B>
|
|
|
|
<DD>
|
|
the command number of this command
|
|
<DT><B>\$</B>
|
|
|
|
<DD>
|
|
if the effective UID is 0, a
|
|
<B>#</B>,
|
|
|
|
otherwise a
|
|
<B>$</B>
|
|
|
|
<DT><B>\</B><I>nnn</I>
|
|
|
|
<DD>
|
|
the character corresponding to the octal number <I>nnn</I>
|
|
<DT><B>\\</B>
|
|
|
|
<DD>
|
|
a backslash
|
|
<DT><B>\[</B>
|
|
|
|
<DD>
|
|
begin a sequence of non-printing characters, which could be used to
|
|
embed a terminal control sequence into the prompt
|
|
<DT><B>\]</B>
|
|
|
|
<DD>
|
|
end a sequence of non-printing characters
|
|
|
|
</DL></DL>
|
|
|
|
<P>
|
|
|
|
The command number and the history number are usually different:
|
|
the history number of a command is its position in the history
|
|
list, which may include commands restored from the history file
|
|
(see
|
|
<FONT SIZE=-1><B>HISTORY</B>
|
|
|
|
</FONT>
|
|
below), while the command number is the position in the sequence
|
|
of commands executed during the current shell session.
|
|
After the string is decoded, it is expanded via
|
|
parameter expansion, command substitution, arithmetic
|
|
expansion, and quote removal, subject to the value of the
|
|
<B>promptvars</B>
|
|
|
|
shell option (see the description of the
|
|
<B>shopt</B>
|
|
|
|
command under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
This can have unwanted side effects if escaped portions of the string
|
|
appear within command substitution or contain characters special to
|
|
word expansion.
|
|
<A NAME="lbCF"> </A>
|
|
<H3>READLINE</H3>
|
|
|
|
This is the library that handles reading input when using an interactive
|
|
shell, unless the
|
|
<B>--noediting</B>
|
|
|
|
option is given at shell invocation.
|
|
Line editing is also used when using the <B>-e</B> option to the
|
|
<B>read</B> builtin.
|
|
By default, the line editing commands are similar to those of Emacs.
|
|
A vi-style line editing interface is also available.
|
|
Line editing can be enabled at any time using the
|
|
<B>-o emacs</B>
|
|
|
|
or
|
|
<B>-o vi</B>
|
|
|
|
options to the
|
|
<B>set</B>
|
|
|
|
builtin (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
To turn off line editing after the shell is running, use the
|
|
<B>+o emacs</B>
|
|
|
|
or
|
|
<B>+o vi</B>
|
|
|
|
options to the
|
|
<B>set</B>
|
|
|
|
builtin.
|
|
<A NAME="lbCG"> </A>
|
|
<H4>Readline Notation</H4>
|
|
|
|
In this section, the Emacs-style notation is used to denote
|
|
keystrokes. Control keys are denoted by C-<I>key</I>, e.g., C-n
|
|
means Control-N. Similarly,
|
|
<I>meta</I>
|
|
|
|
keys are denoted by M-<I>key</I>, so M-x means Meta-X. (On keyboards
|
|
without a
|
|
<I>meta</I>
|
|
|
|
key, M-<I>x</I> means ESC <I>x</I>, i.e., press the Escape key
|
|
then the
|
|
<I>x</I>
|
|
|
|
key. This makes ESC the <I>meta prefix</I>.
|
|
The combination M-C-<I>x</I> means ESC-Control-<I>x</I>,
|
|
or press the Escape key
|
|
then hold the Control key while pressing the
|
|
<I>x</I>
|
|
|
|
key.)
|
|
<P>
|
|
|
|
Readline commands may be given numeric
|
|
<I>arguments</I>,
|
|
|
|
which normally act as a repeat count.
|
|
Sometimes, however, it is the sign of the argument that is significant.
|
|
Passing a negative argument to a command that acts in the forward
|
|
direction (e.g., <B>kill-line</B>) causes that command to act in a
|
|
backward direction.
|
|
Commands whose behavior with arguments deviates from this are noted
|
|
below.
|
|
<P>
|
|
|
|
When a command is described as <I>killing</I> text, the text
|
|
deleted is saved for possible future retrieval
|
|
(<I>yanking</I>). The killed text is saved in a
|
|
<I>kill ring</I>. Consecutive kills cause the text to be
|
|
accumulated into one unit, which can be yanked all at once.
|
|
Commands which do not kill text separate the chunks of text
|
|
on the kill ring.
|
|
<A NAME="lbCH"> </A>
|
|
<H4>Readline Initialization</H4>
|
|
|
|
Readline is customized by putting commands in an initialization
|
|
file (the <I>inputrc</I> file).
|
|
The name of this file is taken from the value of the
|
|
<FONT SIZE=-1><B>INPUTRC</B>
|
|
|
|
</FONT>
|
|
variable. If that variable is unset, the default is
|
|
<A HREF="file:~/.inputrc"><I>~/.inputrc</I></A>.
|
|
|
|
If that file does not exist or cannot be read, the ultimate default is
|
|
<A HREF="file:/etc/inputrc"><I>/etc/inputrc</I></A>.
|
|
|
|
When a program which uses the readline library starts up, the
|
|
initialization file is read, and the key bindings and variables
|
|
are set.
|
|
There are only a few basic constructs allowed in the
|
|
readline initialization file.
|
|
Blank lines are ignored.
|
|
Lines beginning with a <B>#</B> are comments.
|
|
Lines beginning with a <B>$</B> indicate conditional constructs.
|
|
Other lines denote key bindings and variable settings.
|
|
<P>
|
|
|
|
The default key-bindings may be changed with an
|
|
<I>inputrc</I>
|
|
|
|
file.
|
|
Other programs that use this library may add their own commands
|
|
and bindings.
|
|
<P>
|
|
|
|
For example, placing
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
M-Control-u: universal-argument
|
|
</DL>
|
|
|
|
or
|
|
<DL COMPACT><DT><DD>
|
|
C-Meta-u: universal-argument
|
|
</DL>
|
|
|
|
into the
|
|
<I>inputrc</I>
|
|
|
|
would make M-C-u execute the readline command
|
|
<I>universal-argument</I>.
|
|
|
|
<P>
|
|
|
|
The following symbolic character names are recognized:
|
|
<I>RUBOUT</I>,
|
|
|
|
<I>DEL</I>,
|
|
|
|
<I>ESC</I>,
|
|
|
|
<I>LFD</I>,
|
|
|
|
<I>NEWLINE</I>,
|
|
|
|
<I>RET</I>,
|
|
|
|
<I>RETURN</I>,
|
|
|
|
<I>SPC</I>,
|
|
|
|
<I>SPACE</I>,
|
|
|
|
and
|
|
<I>TAB</I>.
|
|
|
|
<P>
|
|
|
|
In addition to command names, readline allows keys to be bound
|
|
to a string that is inserted when the key is pressed (a <I>macro</I>).
|
|
<A NAME="lbCI"> </A>
|
|
<H4>Readline Key Bindings</H4>
|
|
|
|
The syntax for controlling key bindings in the
|
|
<I>inputrc</I>
|
|
|
|
file is simple. All that is required is the name of the
|
|
command or the text of a macro and a key sequence to which
|
|
it should be bound. The name may be specified in one of two ways:
|
|
as a symbolic key name, possibly with <I>Meta-</I> or <I>Control-</I>
|
|
prefixes, or as a key sequence.
|
|
<P>
|
|
|
|
When using the form <B>keyname</B>:<I>function-name</I> or <I>macro</I>,
|
|
<I>keyname</I>
|
|
|
|
is the name of a key spelled out in English. For example:
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
Control-u: universal-argument
|
|
<BR>
|
|
|
|
Meta-Rubout: backward-kill-word
|
|
<BR>
|
|
|
|
Control-o: "> output"
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
In the above example,
|
|
<I>C-u</I>
|
|
|
|
is bound to the function
|
|
<B>universal-argument</B>,
|
|
|
|
<I>M-DEL</I>
|
|
|
|
is bound to the function
|
|
<B>backward-kill-word</B>,
|
|
|
|
and
|
|
<I>C-o</I>
|
|
|
|
is bound to run the macro
|
|
expressed on the right hand side (that is, to insert the text
|
|
<TT>> output</TT>
|
|
|
|
into the line).
|
|
<P>
|
|
|
|
In the second form, <B>"keyseq"</B>:<I>function-name</I> or <I>macro</I>,
|
|
<B>keyseq</B>
|
|
|
|
differs from
|
|
<B>keyname</B>
|
|
|
|
above in that strings denoting
|
|
an entire key sequence may be specified by placing the sequence
|
|
within double quotes. Some GNU Emacs style key escapes can be
|
|
used, as in the following example, but the symbolic character names
|
|
are not recognized.
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
"\C-u": universal-argument
|
|
<BR>
|
|
|
|
"\C-x\C-r": re-read-init-file
|
|
<BR>
|
|
|
|
"\e[11~": "Function Key 1"
|
|
</DL>
|
|
|
|
<P>
|
|
|
|
In this example,
|
|
<I>C-u</I>
|
|
|
|
is again bound to the function
|
|
<B>universal-argument</B>.
|
|
|
|
<I>C-x C-r</I>
|
|
|
|
is bound to the function
|
|
<B>re-read-init-file</B>,
|
|
|
|
and
|
|
<I>ESC [ 1 1 ~</I>
|
|
|
|
is bound to insert the text
|
|
<TT>Function Key 1</TT>.
|
|
|
|
<P>
|
|
|
|
The full set of GNU Emacs style escape sequences is
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>\C-</B>
|
|
|
|
<DD>
|
|
control prefix
|
|
<DT><B>\M-</B>
|
|
|
|
<DD>
|
|
meta prefix
|
|
<DT><B>\e</B>
|
|
|
|
<DD>
|
|
an escape character
|
|
<DT><B>\\</B>
|
|
|
|
<DD>
|
|
backslash
|
|
<DT><B>\</B>
|
|
|
|
<DD>
|
|
literal "
|
|
<DT><B>\aq</B>
|
|
|
|
<DD>
|
|
literal aq
|
|
</DL></DL>
|
|
|
|
|
|
<P>
|
|
|
|
In addition to the GNU Emacs style escape sequences, a second
|
|
set of backslash escapes is available:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>\a</B>
|
|
|
|
<DD>
|
|
alert (bell)
|
|
<DT><B>\b</B>
|
|
|
|
<DD>
|
|
backspace
|
|
<DT><B>\d</B>
|
|
|
|
<DD>
|
|
delete
|
|
<DT><B>\f</B>
|
|
|
|
<DD>
|
|
form feed
|
|
<DT><B>\n</B>
|
|
|
|
<DD>
|
|
newline
|
|
<DT><B>\r</B>
|
|
|
|
<DD>
|
|
carriage return
|
|
<DT><B>\t</B>
|
|
|
|
<DD>
|
|
horizontal tab
|
|
<DT><B>\v</B>
|
|
|
|
<DD>
|
|
vertical tab
|
|
<DT><B>\</B><I>nnn</I>
|
|
|
|
<DD>
|
|
the eight-bit character whose value is the octal value <I>nnn</I>
|
|
(one to three digits)
|
|
<DT><B>\x</B><I>HH</I>
|
|
|
|
<DD>
|
|
the eight-bit character whose value is the hexadecimal value <I>HH</I>
|
|
(one or two hex digits)
|
|
</DL></DL>
|
|
|
|
|
|
<P>
|
|
|
|
When entering the text of a macro, single or double quotes must
|
|
be used to indicate a macro definition.
|
|
Unquoted text is assumed to be a function name.
|
|
In the macro body, the backslash escapes described above are expanded.
|
|
Backslash will quote any other character in the macro text,
|
|
including " and aq.
|
|
<P>
|
|
|
|
<B>Bash</B>
|
|
|
|
allows the current readline key bindings to be displayed or modified
|
|
with the
|
|
<B>bind</B>
|
|
|
|
builtin command. The editing mode may be switched during interactive
|
|
use by using the
|
|
<B>-o</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<A NAME="lbCJ"> </A>
|
|
<H4>Readline Variables</H4>
|
|
|
|
Readline has variables that can be used to further customize its
|
|
behavior. A variable may be set in the
|
|
<I>inputrc</I>
|
|
|
|
file with a statement of the form
|
|
<DL COMPACT><DT><DD>
|
|
<P>
|
|
|
|
<B>set</B> <I>variable-name</I> <I>value</I>
|
|
</DL>
|
|
|
|
or using the <B>bind</B> builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below).
|
|
<P>
|
|
|
|
Except where noted, readline variables can take the values
|
|
<B>On</B>
|
|
|
|
or
|
|
<B>Off</B>
|
|
|
|
(without regard to case).
|
|
Unrecognized variable names are ignored.
|
|
When a variable value is read, empty or null values, "on" (case-insensitive),
|
|
and "1" are equivalent to <B>On</B>. All other values are equivalent to
|
|
<B>Off</B>.
|
|
The variables and their default values are:
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>active-region-start-color </B>
|
|
|
|
<DD>
|
|
A string variable that controls the text color and background when displaying
|
|
the text in the active region (see the description of
|
|
<B>enable-active-region</B> below).
|
|
This string must not take up any physical character positions on the display,
|
|
so it should consist only of terminal escape sequences.
|
|
It is output to the terminal before displaying the text in the active region.
|
|
This variable is reset to the default value whenever the terminal type changes.
|
|
The default value is the string that puts the terminal in standout mode,
|
|
as obtained from the terminal's terminfo description.
|
|
A sample value might be <TT>"\e[01;33m"</TT>.
|
|
<DT><B>active-region-end-color </B>
|
|
|
|
<DD>
|
|
A string variable that "undoes" the effects of <B>active-region-start-color</B>
|
|
and restores "normal" terminal display appearance after displaying text
|
|
in the active region.
|
|
This string must not take up any physical character positions on the display,
|
|
so it should consist only of terminal escape sequences.
|
|
It is output to the terminal after displaying the text in the active region.
|
|
This variable is reset to the default value whenever the terminal type changes.
|
|
The default value is the string that restores the terminal from standout mode,
|
|
as obtained from the terminal's terminfo description.
|
|
A sample value might be <TT>"\e[0m"</TT>.
|
|
<DT><B>bell-style (audible)</B>
|
|
|
|
<DD>
|
|
Controls what happens when readline wants to ring the terminal bell.
|
|
If set to <B>none</B>, readline never rings the bell. If set to
|
|
<B>visible</B>, readline uses a visible bell if one is available.
|
|
If set to <B>audible</B>, readline attempts to ring the terminal's bell.
|
|
<DT><B>bind-tty-special-chars (On)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline attempts to bind the control characters
|
|
treated specially by the kernel's terminal driver to their readline
|
|
equivalents.
|
|
<DT><B>blink-matching-paren (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline attempts to briefly move the cursor to an
|
|
opening parenthesis when a closing parenthesis is inserted.
|
|
<DT><B>colored-completion-prefix (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, when listing completions, readline displays the
|
|
common prefix of the set of possible completions using a different color.
|
|
The color definitions are taken from the value of the <B>LS_COLORS</B>
|
|
environment variable.
|
|
If there is a color definition in <B>$LS_COLORS</B> for the custom suffix
|
|
"readline-colored-completion-prefix", readline uses this color for
|
|
the common prefix instead of its default.
|
|
<DT><B>colored-stats (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline displays possible completions using different
|
|
colors to indicate their file type.
|
|
The color definitions are taken from the value of the <B>LS_COLORS</B>
|
|
environment variable.
|
|
<DT><B>comment-begin (``#'')</B>
|
|
|
|
<DD>
|
|
The string that is inserted when the readline
|
|
<B>insert-comment</B>
|
|
|
|
command is executed.
|
|
This command is bound to
|
|
<B>M-#</B>
|
|
|
|
in emacs mode and to
|
|
<B>#</B>
|
|
|
|
in vi command mode.
|
|
<DT><B>completion-display-width (-1)</B>
|
|
|
|
<DD>
|
|
The number of screen columns used to display possible matches
|
|
when performing completion.
|
|
The value is ignored if it is less than 0 or greater than the terminal
|
|
screen width.
|
|
A value of 0 will cause matches to be displayed one per line.
|
|
The default value is -1.
|
|
<DT><B>completion-ignore-case (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline performs filename matching and completion
|
|
in a case-insensitive fashion.
|
|
<DT><B>completion-map-case (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, and <B>completion-ignore-case</B> is enabled, readline
|
|
treats hyphens (<I>-</I>) and underscores (<I>_</I>) as equivalent when
|
|
performing case-insensitive filename matching and completion.
|
|
<DT><B>completion-prefix-display-length (0)</B>
|
|
|
|
<DD>
|
|
The length in characters of the common prefix of a list of possible
|
|
completions that is displayed without modification. When set to a
|
|
value greater than zero, common prefixes longer than this value are
|
|
replaced with an ellipsis when displaying possible completions.
|
|
<DT><B>completion-query-items (100)</B>
|
|
|
|
<DD>
|
|
This determines when the user is queried about viewing
|
|
the number of possible completions
|
|
generated by the <B>possible-completions</B> command.
|
|
It may be set to any integer value greater than or equal to zero.
|
|
If the number of possible completions is greater than
|
|
or equal to the value of this variable,
|
|
readline will ask whether or not the user wishes to view them;
|
|
otherwise they are simply listed on the terminal.
|
|
A zero value means readline should never ask; negative values are
|
|
treated as zero.
|
|
<DT><B>convert-meta (On)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline will convert characters with the
|
|
eighth bit set to an ASCII key sequence
|
|
by stripping the eighth bit and prefixing an
|
|
escape character (in effect, using escape as the <I>meta prefix</I>).
|
|
The default is <I>On</I>, but readline will set it to <I>Off</I> if the
|
|
locale contains eight-bit characters.
|
|
This variable is dependent on the <B>LC_CTYPE</B> locale category, and
|
|
may change if the locale is changed.
|
|
<DT><B>disable-completion (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline will inhibit word completion. Completion
|
|
characters will be inserted into the line as if they had been
|
|
mapped to <B>self-insert</B>.
|
|
<DT><B>echo-control-characters (On)</B>
|
|
|
|
<DD>
|
|
When set to <B>On</B>, on operating systems that indicate they support it,
|
|
readline echoes a character corresponding to a signal generated from the
|
|
keyboard.
|
|
<DT><B>editing-mode (emacs)</B>
|
|
|
|
<DD>
|
|
Controls whether readline begins with a set of key bindings similar
|
|
to <I>Emacs</I> or <I>vi</I>.
|
|
<B>editing-mode</B>
|
|
|
|
can be set to either
|
|
<B>emacs</B>
|
|
|
|
or
|
|
<B>vi</B>.
|
|
|
|
<DT><B>emacs-mode-string (@)</B>
|
|
|
|
<DD>
|
|
If the <I>show-mode-in-prompt</I> variable is enabled,
|
|
this string is displayed immediately before the last line of the primary
|
|
prompt when emacs editing mode is active. The value is expanded like a
|
|
key binding, so the standard set of meta- and control prefixes and
|
|
backslash escape sequences is available.
|
|
Use the \1 and \2 escapes to begin and end sequences of
|
|
non-printing characters, which can be used to embed a terminal control
|
|
sequence into the mode string.
|
|
<DT><B>enable-active-region (On)</B>
|
|
|
|
<DD>
|
|
The <I>point</I> is the current cursor position, and <I>mark</I> refers
|
|
to a saved cursor position.
|
|
The text between the point and mark is referred to as the <I>region</I>.
|
|
When this variable is set to <I>On</I>, readline allows certain commands
|
|
to designate the region as <I>active</I>.
|
|
When the region is active, readline highlights the text in the region using
|
|
the value of the <B>active-region-start-color</B>, which defaults to the
|
|
string that enables
|
|
the terminal's standout mode.
|
|
The active region shows the text inserted by bracketed-paste and any
|
|
matching text found by incremental and non-incremental history searches.
|
|
<DT><B>enable-bracketed-paste (On)</B>
|
|
|
|
<DD>
|
|
When set to <B>On</B>, readline configures the terminal to insert each
|
|
paste into the editing buffer as a single string of characters, instead
|
|
of treating each character as if it had been read from the keyboard.
|
|
This prevents readline from executing any editing commands bound to key
|
|
sequences appearing in the pasted text.
|
|
<DT><B>enable-keypad (Off)</B>
|
|
|
|
<DD>
|
|
When set to <B>On</B>, readline will try to enable the application
|
|
keypad when it is called. Some systems need this to enable the
|
|
arrow keys.
|
|
<DT><B>enable-meta-key (On)</B>
|
|
|
|
<DD>
|
|
When set to <B>On</B>, readline will try to enable any meta modifier
|
|
key the terminal claims to support when it is called. On many terminals,
|
|
the meta key is used to send eight-bit characters.
|
|
<DT><B>expand-tilde (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, tilde expansion is performed when readline
|
|
attempts word completion.
|
|
<DT><B>history-preserve-point (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, the history code attempts to place point at the
|
|
same location on each history line retrieved with <B>previous-history</B>
|
|
or <B>next-history</B>.
|
|
<DT><B>history-size (unset)</B>
|
|
|
|
<DD>
|
|
Set the maximum number of history entries saved in the history list.
|
|
If set to zero, any existing history entries are deleted and no new entries
|
|
are saved.
|
|
If set to a value less than zero, the number of history entries is not
|
|
limited.
|
|
By default, the number of history entries is set to the value of the
|
|
<B>HISTSIZE</B> shell variable.
|
|
If an attempt is made to set <I>history-size</I> to a non-numeric value,
|
|
the maximum number of history entries will be set to 500.
|
|
<DT><B>horizontal-scroll-mode (Off)</B>
|
|
|
|
<DD>
|
|
When set to <B>On</B>, makes readline use a single line for display,
|
|
scrolling the input horizontally on a single screen line when it
|
|
becomes longer than the screen width rather than wrapping to a new line.
|
|
This setting is automatically enabled for terminals of height 1.
|
|
<DT><B>input-meta (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline will enable eight-bit input (that is,
|
|
it will not strip the eighth bit from the characters it reads),
|
|
regardless of what the terminal claims it can support. The name
|
|
<B>meta-flag</B>
|
|
|
|
is a synonym for this variable.
|
|
The default is <I>Off</I>, but readline will set it to <I>On</I> if the
|
|
locale contains eight-bit characters.
|
|
This variable is dependent on the <B>LC_CTYPE</B> locale category, and
|
|
may change if the locale is changed.
|
|
<DT><B>isearch-terminators (``C-[C-J'')</B>
|
|
|
|
<DD>
|
|
The string of characters that should terminate an incremental
|
|
search without subsequently executing the character as a command.
|
|
If this variable has not been given a value, the characters
|
|
<I>ESC</I> and <I>C-J</I> will terminate an incremental search.
|
|
<DT><B>keymap (emacs)</B>
|
|
|
|
<DD>
|
|
Set the current readline keymap. The set of valid keymap names is
|
|
<I>emacs, emacs-standard, emacs-meta, emacs-ctlx, vi,
|
|
vi-command</I>, and
|
|
<I>vi-insert</I>.
|
|
|
|
<I>vi</I> is equivalent to <I>vi-command</I>; <I>emacs</I> is
|
|
equivalent to <I>emacs-standard</I>. The default value is
|
|
<I>emacs</I>;
|
|
|
|
the value of
|
|
<B>editing-mode</B>
|
|
|
|
also affects the default keymap.
|
|
<DT><B>keyseq-timeout (500)</B>
|
|
|
|
<DD>
|
|
Specifies the duration <I>readline</I> will wait for a character when reading an
|
|
ambiguous key sequence (one that can form a complete key sequence using
|
|
the input read so far, or can take additional input to complete a longer
|
|
key sequence).
|
|
If no input is received within the timeout, <I>readline</I> will use the shorter
|
|
but complete key sequence.
|
|
The value is specified in milliseconds, so a value of 1000 means that
|
|
<I>readline</I> will wait one second for additional input.
|
|
If this variable is set to a value less than or equal to zero, or to a
|
|
non-numeric value, <I>readline</I> will wait until another key is pressed to
|
|
decide which key sequence to complete.
|
|
<DT><B>mark-directories (On)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, completed directory names have a slash
|
|
appended.
|
|
<DT><B>mark-modified-lines (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, history lines that have been modified are displayed
|
|
with a preceding asterisk (<B>*</B>).
|
|
<DT><B>mark-symlinked-directories (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, completed names which are symbolic links to directories
|
|
have a slash appended (subject to the value of
|
|
<B>mark-directories</B>).
|
|
<DT><B>match-hidden-files (On)</B>
|
|
|
|
<DD>
|
|
This variable, when set to <B>On</B>, causes readline to match files whose
|
|
names begin with a `.' (hidden files) when performing filename
|
|
completion.
|
|
If set to <B>Off</B>, the leading `.' must be
|
|
supplied by the user in the filename to be completed.
|
|
<DT><B>menu-complete-display-prefix (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, menu completion displays the common prefix of the
|
|
list of possible completions (which may be empty) before cycling through
|
|
the list.
|
|
<DT><B>output-meta (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline will display characters with the
|
|
eighth bit set directly rather than as a meta-prefixed escape
|
|
sequence.
|
|
The default is <I>Off</I>, but readline will set it to <I>On</I> if the
|
|
locale contains eight-bit characters.
|
|
This variable is dependent on the <B>LC_CTYPE</B> locale category, and
|
|
may change if the locale is changed.
|
|
<DT><B>page-completions (On)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline uses an internal <I>more</I>-like pager
|
|
to display a screenful of possible completions at a time.
|
|
<DT><B>print-completions-horizontally (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline will display completions with matches
|
|
sorted horizontally in alphabetical order, rather than down the screen.
|
|
<DT><B>revert-all-at-newline (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, readline will undo all changes to history lines
|
|
before returning when <B>accept-line</B> is executed. By default,
|
|
history lines may be modified and retain individual undo lists across
|
|
calls to <B>readline</B>.
|
|
<DT><B>show-all-if-ambiguous (Off)</B>
|
|
|
|
<DD>
|
|
This alters the default behavior of the completion functions. If
|
|
set to
|
|
<B>On</B>,
|
|
|
|
words which have more than one possible completion cause the
|
|
matches to be listed immediately instead of ringing the bell.
|
|
<DT><B>show-all-if-unmodified (Off)</B>
|
|
|
|
<DD>
|
|
This alters the default behavior of the completion functions in
|
|
a fashion similar to <B>show-all-if-ambiguous</B>.
|
|
If set to
|
|
<B>On</B>,
|
|
|
|
words which have more than one possible completion without any
|
|
possible partial completion (the possible completions don't share
|
|
a common prefix) cause the matches to be listed immediately instead
|
|
of ringing the bell.
|
|
<DT><B>show-mode-in-prompt (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, add a string to the beginning of the prompt
|
|
indicating the editing mode: emacs, vi command, or vi insertion.
|
|
The mode strings are user-settable (e.g., <I>emacs-mode-string</I>).
|
|
<DT><B>skip-completed-text (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, this alters the default completion behavior when
|
|
inserting a single match into the line. It's only active when
|
|
performing completion in the middle of a word. If enabled, readline
|
|
does not insert characters from the completion that match characters
|
|
after point in the word being completed, so portions of the word
|
|
following the cursor are not duplicated.
|
|
<DT><B>vi-cmd-mode-string ((cmd))</B>
|
|
|
|
<DD>
|
|
If the <I>show-mode-in-prompt</I> variable is enabled,
|
|
this string is displayed immediately before the last line of the primary
|
|
prompt when vi editing mode is active and in command mode.
|
|
The value is expanded like a
|
|
key binding, so the standard set of meta- and control prefixes and
|
|
backslash escape sequences is available.
|
|
Use the \1 and \2 escapes to begin and end sequences of
|
|
non-printing characters, which can be used to embed a terminal control
|
|
sequence into the mode string.
|
|
<DT><B>vi-ins-mode-string ((ins))</B>
|
|
|
|
<DD>
|
|
If the <I>show-mode-in-prompt</I> variable is enabled,
|
|
this string is displayed immediately before the last line of the primary
|
|
prompt when vi editing mode is active and in insertion mode.
|
|
The value is expanded like a
|
|
key binding, so the standard set of meta- and control prefixes and
|
|
backslash escape sequences is available.
|
|
Use the \1 and \2 escapes to begin and end sequences of
|
|
non-printing characters, which can be used to embed a terminal control
|
|
sequence into the mode string.
|
|
<DT><B>visible-stats (Off)</B>
|
|
|
|
<DD>
|
|
If set to <B>On</B>, a character denoting a file's type as reported
|
|
by <I>stat</I>(2) is appended to the filename when listing possible
|
|
completions.
|
|
|
|
</DL>
|
|
<A NAME="lbCK"> </A>
|
|
<H4>Readline Conditional Constructs</H4>
|
|
|
|
Readline implements a facility similar in spirit to the conditional
|
|
compilation features of the C preprocessor which allows key
|
|
bindings and variable settings to be performed as the result
|
|
of tests. There are four parser directives used.
|
|
<DL COMPACT>
|
|
<DT><B>$if</B><DD>
|
|
The
|
|
<B>$if</B>
|
|
|
|
construct allows bindings to be made based on the
|
|
editing mode, the terminal being used, or the application using
|
|
readline. The text of the test, after any comparison operator,
|
|
<BR> extends to the end of the line;
|
|
unless otherwise noted, no characters are required to isolate it.
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>mode</B><DD>
|
|
The <B>mode=</B> form of the <B>$if</B> directive is used to test
|
|
whether readline is in emacs or vi mode.
|
|
This may be used in conjunction
|
|
with the <B>set keymap</B> command, for instance, to set bindings in
|
|
the <I>emacs-standard</I> and <I>emacs-ctlx</I> keymaps only if
|
|
readline is starting out in emacs mode.
|
|
<DT><B>term</B><DD>
|
|
The <B>term=</B> form may be used to include terminal-specific
|
|
key bindings, perhaps to bind the key sequences output by the
|
|
terminal's function keys. The word on the right side of the
|
|
<B>=</B>
|
|
|
|
is tested against both the full name of the terminal and the portion
|
|
of the terminal name before the first <B>-</B>. This allows
|
|
<I>sun</I>
|
|
|
|
to match both
|
|
<I>sun</I>
|
|
|
|
and
|
|
<I>sun-cmd</I>,
|
|
|
|
for instance.
|
|
<DT><B>version</B><DD>
|
|
The <B>version</B> test may be used to perform comparisons against
|
|
specific readline versions.
|
|
The <B>version</B> expands to the current readline version.
|
|
The set of comparison operators includes
|
|
<B>=</B>,
|
|
|
|
(and
|
|
<B>==</B>),
|
|
|
|
<B>!=</B>,
|
|
|
|
<B><=</B>,
|
|
|
|
<B>>=</B>,
|
|
|
|
<B><</B>,
|
|
|
|
and
|
|
<B>></B>.
|
|
|
|
The version number supplied on the right side of the operator consists
|
|
of a major version number, an optional decimal point, and an optional
|
|
minor version (e.g., <B>7.1</B>). If the minor version is omitted, it
|
|
is assumed to be <B>0</B>.
|
|
The operator may be separated from the string <B>version</B>
|
|
and from the version number argument by whitespace.
|
|
<DT><B>application</B><DD>
|
|
The <B>application</B> construct is used to include
|
|
application-specific settings. Each program using the readline
|
|
library sets the <I>application name</I>, and an initialization
|
|
file can test for a particular value.
|
|
This could be used to bind key sequences to functions useful for
|
|
a specific program. For instance, the following command adds a
|
|
key sequence that quotes the current or previous word in <B>bash</B>:
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
<PRE>
|
|
<B>$if</B> Bash
|
|
# Quote the current or previous word
|
|
"\C-xq": "\eb\"\ef\""
|
|
<B>$endif</B>
|
|
</PRE>
|
|
|
|
</DL>
|
|
|
|
<DT><I>variable</I><DD>
|
|
The <I>variable</I> construct provides simple equality tests for readline
|
|
variables and values.
|
|
The permitted comparison operators are <I>=</I>, <I>==</I>, and <I>!=</I>.
|
|
The variable name must be separated from the comparison operator by
|
|
whitespace; the operator may be separated from the value on the right hand
|
|
side by whitespace.
|
|
Both string and boolean variables may be tested. Boolean variables must be
|
|
tested against the values <I>on</I> and <I>off</I>.
|
|
</DL></DL>
|
|
|
|
<DT><B>$endif</B><DD>
|
|
This command, as seen in the previous example, terminates an
|
|
<B>$if</B> command.
|
|
<DT><B>$else</B><DD>
|
|
Commands in this branch of the <B>$if</B> directive are executed if
|
|
the test fails.
|
|
<DT><B>$include</B><DD>
|
|
This directive takes a single filename as an argument and reads commands
|
|
and bindings from that file. For example, the following directive
|
|
would read <A HREF="file:/etc/inputrc"><I>/etc/inputrc</I></A>:
|
|
<P>
|
|
<DL COMPACT><DT><DD>
|
|
<PRE>
|
|
<B>$include</B> <A HREF="file:/etc/inputrc"><I>/etc/inputrc</I></A>
|
|
</PRE>
|
|
|
|
</DL>
|
|
|
|
</DL>
|
|
<A NAME="lbCL"> </A>
|
|
<H4>Searching</H4>
|
|
|
|
Readline provides commands for searching through the command history
|
|
(see
|
|
<FONT SIZE=-1><B>HISTORY</B>
|
|
|
|
</FONT>
|
|
below) for lines containing a specified string.
|
|
There are two search modes:
|
|
<I>incremental</I>
|
|
|
|
and
|
|
<I>non-incremental</I>.
|
|
|
|
<P>
|
|
|
|
Incremental searches begin before the user has finished typing the
|
|
search string.
|
|
As each character of the search string is typed, readline displays
|
|
the next entry from the history matching the string typed so far.
|
|
An incremental search requires only as many characters as needed to
|
|
find the desired history entry.
|
|
The characters present in the value of the <B>isearch-terminators</B>
|
|
variable are used to terminate an incremental search.
|
|
If that variable has not been assigned a value the Escape and
|
|
Control-J characters will terminate an incremental search.
|
|
Control-G will abort an incremental search and restore the original
|
|
line.
|
|
When the search is terminated, the history entry containing the
|
|
search string becomes the current line.
|
|
<P>
|
|
|
|
To find other matching entries in the history list, type Control-S or
|
|
Control-R as appropriate.
|
|
This will search backward or forward in the history for the next
|
|
entry matching the search string typed so far.
|
|
Any other key sequence bound to a readline command will terminate
|
|
the search and execute that command.
|
|
For instance, a <I>newline</I> will terminate the search and accept
|
|
the line, thereby executing the command from the history list.
|
|
<P>
|
|
|
|
Readline remembers the last incremental search string. If two
|
|
Control-Rs are typed without any intervening characters defining a
|
|
new search string, any remembered search string is used.
|
|
<P>
|
|
|
|
Non-incremental searches read the entire search string before starting
|
|
to search for matching history lines. The search string may be
|
|
typed by the user or be part of the contents of the current line.
|
|
<A NAME="lbCM"> </A>
|
|
<H4>Readline Command Names</H4>
|
|
|
|
The following is a list of the names of the commands and the default
|
|
key sequences to which they are bound.
|
|
Command names without an accompanying key sequence are unbound by default.
|
|
In the following descriptions, <I>point</I> refers to the current cursor
|
|
position, and <I>mark</I> refers to a cursor position saved by the
|
|
<B>set-mark</B> command.
|
|
The text between the point and mark is referred to as the <I>region</I>.
|
|
<A NAME="lbCN"> </A>
|
|
<H4>Commands for Moving</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>beginning-of-line (C-a)</B>
|
|
|
|
<DD>
|
|
Move to the start of the current line.
|
|
<DT><B>end-of-line (C-e)</B>
|
|
|
|
<DD>
|
|
Move to the end of the line.
|
|
<DT><B>forward-char (C-f)</B>
|
|
|
|
<DD>
|
|
Move forward a character.
|
|
<DT><B>backward-char (C-b)</B>
|
|
|
|
<DD>
|
|
Move back a character.
|
|
<DT><B>forward-word (M-f)</B>
|
|
|
|
<DD>
|
|
Move forward to the end of the next word. Words are composed of
|
|
alphanumeric characters (letters and digits).
|
|
<DT><B>backward-word (M-b)</B>
|
|
|
|
<DD>
|
|
Move back to the start of the current or previous word.
|
|
Words are composed of alphanumeric characters (letters and digits).
|
|
<DT><B>shell-forward-word</B>
|
|
|
|
<DD>
|
|
Move forward to the end of the next word.
|
|
Words are delimited by non-quoted shell metacharacters.
|
|
<DT><B>shell-backward-word</B>
|
|
|
|
<DD>
|
|
Move back to the start of the current or previous word.
|
|
Words are delimited by non-quoted shell metacharacters.
|
|
<DT><B>previous-screen-line</B>
|
|
|
|
<DD>
|
|
Attempt to move point to the same physical screen column on the previous
|
|
physical screen line. This will not have the desired effect if the current
|
|
readline line does not take up more than one physical line or if point is not
|
|
greater than the length of the prompt plus the screen width.
|
|
<DT><B>next-screen-line</B>
|
|
|
|
<DD>
|
|
Attempt to move point to the same physical screen column on the next
|
|
physical screen line. This will not have the desired effect if the current
|
|
readline line does not take up more than one physical line or if the length
|
|
of the current readline line is not greater than the length of the prompt
|
|
plus the screen width.
|
|
<DT><B>clear-display (M-C-l)</B>
|
|
|
|
<DD>
|
|
Clear the screen and, if possible, the terminal's scrollback buffer,
|
|
then redraw the current line,
|
|
leaving the current line at the top of the screen.
|
|
<DT><B>clear-screen (C-l)</B>
|
|
|
|
<DD>
|
|
Clear the screen,
|
|
then redraw the current line,
|
|
leaving the current line at the top of the screen.
|
|
With an argument, refresh the current line without clearing the
|
|
screen.
|
|
<DT><B>redraw-current-line</B>
|
|
|
|
<DD>
|
|
Refresh the current line.
|
|
|
|
</DL>
|
|
<A NAME="lbCO"> </A>
|
|
<H4>Commands for Manipulating the History</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>accept-line (Newline, Return)</B>
|
|
|
|
<DD>
|
|
Accept the line regardless of where the cursor is. If this line is
|
|
non-empty, add it to the history list according to the state of the
|
|
<FONT SIZE=-1><B>HISTCONTROL</B>
|
|
|
|
</FONT>
|
|
variable. If the line is a modified history
|
|
line, then restore the history line to its original state.
|
|
<DT><B>previous-history (C-p)</B>
|
|
|
|
<DD>
|
|
Fetch the previous command from the history list, moving back in
|
|
the list.
|
|
<DT><B>next-history (C-n)</B>
|
|
|
|
<DD>
|
|
Fetch the next command from the history list, moving forward in the
|
|
list.
|
|
<DT><B>beginning-of-history (M-<)</B>
|
|
|
|
<DD>
|
|
Move to the first line in the history.
|
|
<DT><B>end-of-history (M->)</B>
|
|
|
|
<DD>
|
|
Move to the end of the input history, i.e., the line currently being
|
|
entered.
|
|
<DT><B>operate-and-get-next (C-o)</B>
|
|
|
|
<DD>
|
|
Accept the current line for execution and fetch the next line
|
|
relative to the current line from the history for editing.
|
|
A numeric argument, if supplied, specifies the history entry to use instead
|
|
of the current line.
|
|
<DT><B>fetch-history</B>
|
|
|
|
<DD>
|
|
With a numeric argument, fetch that entry from the history list
|
|
and make it the current line.
|
|
Without an argument, move back to the first entry in the history list.
|
|
<DT><B>reverse-search-history (C-r)</B>
|
|
|
|
<DD>
|
|
Search backward starting at the current line and moving `up' through
|
|
the history as necessary. This is an incremental search.
|
|
<DT><B>forward-search-history (C-s)</B>
|
|
|
|
<DD>
|
|
Search forward starting at the current line and moving `down' through
|
|
the history as necessary. This is an incremental search.
|
|
<DT><B>non-incremental-reverse-search-history (M-p)</B>
|
|
|
|
<DD>
|
|
Search backward through the history starting at the current line
|
|
using a non-incremental search for a string supplied by the user.
|
|
<DT><B>non-incremental-forward-search-history (M-n)</B>
|
|
|
|
<DD>
|
|
Search forward through the history using a non-incremental search for
|
|
a string supplied by the user.
|
|
<DT><B>history-search-forward</B>
|
|
|
|
<DD>
|
|
Search forward through the history for the string of characters
|
|
between the start of the current line and the point.
|
|
This is a non-incremental search.
|
|
<DT><B>history-search-backward</B>
|
|
|
|
<DD>
|
|
Search backward through the history for the string of characters
|
|
between the start of the current line and the point.
|
|
This is a non-incremental search.
|
|
<DT><B>history-substring-search-backward</B>
|
|
|
|
<DD>
|
|
Search backward through the history for the string of characters
|
|
between the start of the current line and the current cursor
|
|
position (the <I>point</I>).
|
|
The search string may match anywhere in a history line.
|
|
This is a non-incremental search.
|
|
<DT><B>history-substring-search-forward</B>
|
|
|
|
<DD>
|
|
Search forward through the history for the string of characters
|
|
between the start of the current line and the point.
|
|
The search string may match anywhere in a history line.
|
|
This is a non-incremental search.
|
|
<DT><B>yank-nth-arg (M-C-y)</B>
|
|
|
|
<DD>
|
|
Insert the first argument to the previous command (usually
|
|
the second word on the previous line) at point.
|
|
With an argument
|
|
<I>n</I>,
|
|
|
|
insert the <I>n</I>th word from the previous command (the words
|
|
in the previous command begin with word 0). A negative argument
|
|
inserts the <I>n</I>th word from the end of the previous command.
|
|
Once the argument <I>n</I> is computed, the argument is extracted
|
|
as if the "!<I>n</I>" history expansion had been specified.
|
|
<DT><B>yank-last-arg (M-., M-_)</B>
|
|
|
|
<DD>
|
|
Insert the last argument to the previous command (the last word of
|
|
the previous history entry).
|
|
With a numeric argument, behave exactly like <B>yank-nth-arg</B>.
|
|
Successive calls to <B>yank-last-arg</B> move back through the history
|
|
list, inserting the last word (or the word specified by the argument to
|
|
the first call) of each line in turn.
|
|
Any numeric argument supplied to these successive calls determines
|
|
the direction to move through the history. A negative argument switches
|
|
the direction through the history (back or forward).
|
|
The history expansion facilities are used to extract the last word,
|
|
as if the "!$" history expansion had been specified.
|
|
<DT><B>shell-expand-line (M-C-e)</B>
|
|
|
|
<DD>
|
|
Expand the line as the shell does. This
|
|
performs alias and history expansion as well as all of the shell
|
|
word expansions. See
|
|
<FONT SIZE=-1><B>HISTORY EXPANSION</B>
|
|
|
|
</FONT>
|
|
below for a description of history expansion.
|
|
<DT><B>history-expand-line (M-^)</B>
|
|
|
|
<DD>
|
|
Perform history expansion on the current line.
|
|
See
|
|
<FONT SIZE=-1><B>HISTORY EXPANSION</B>
|
|
|
|
</FONT>
|
|
below for a description of history expansion.
|
|
<DT><B>magic-space</B>
|
|
|
|
<DD>
|
|
Perform history expansion on the current line and insert a space.
|
|
See
|
|
<FONT SIZE=-1><B>HISTORY EXPANSION</B>
|
|
|
|
</FONT>
|
|
below for a description of history expansion.
|
|
<DT><B>alias-expand-line</B>
|
|
|
|
<DD>
|
|
Perform alias expansion on the current line.
|
|
See
|
|
<FONT SIZE=-1><B>ALIASES</B>
|
|
|
|
</FONT>
|
|
above for a description of alias expansion.
|
|
<DT><B>history-and-alias-expand-line</B>
|
|
|
|
<DD>
|
|
Perform history and alias expansion on the current line.
|
|
<DT><B>insert-last-argument (M-., M-_)</B>
|
|
|
|
<DD>
|
|
A synonym for <B>yank-last-arg</B>.
|
|
<DT><B>edit-and-execute-command (C-x C-e)</B>
|
|
|
|
<DD>
|
|
Invoke an editor on the current command line, and execute the result as shell
|
|
commands.
|
|
<B>Bash</B> attempts to invoke
|
|
<FONT SIZE=-1><B>$VISUAL</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>$EDITOR</B>,
|
|
|
|
</FONT>
|
|
and <I>emacs</I> as the editor, in that order.
|
|
|
|
</DL>
|
|
<A NAME="lbCP"> </A>
|
|
<H4>Commands for Changing Text</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B></B><I>end-of-file</I> (usually C-d)
|
|
|
|
<DD>
|
|
The character indicating end-of-file as set, for example, by
|
|
<TT>stty</TT>.
|
|
|
|
If this character is read when there are no characters
|
|
on the line, and point is at the beginning of the line, readline
|
|
interprets it as the end of input and returns
|
|
<FONT SIZE=-1><B>EOF</B>.
|
|
|
|
</FONT>
|
|
<DT><B>delete-char (C-d)</B>
|
|
|
|
<DD>
|
|
Delete the character at point.
|
|
If this function is bound to the
|
|
same character as the tty <B>EOF</B> character, as <B>C-d</B>
|
|
commonly is, see above for the effects.
|
|
<DT><B>backward-delete-char (Rubout)</B>
|
|
|
|
<DD>
|
|
Delete the character behind the cursor. When given a numeric argument,
|
|
save the deleted text on the kill ring.
|
|
<DT><B>forward-backward-delete-char</B>
|
|
|
|
<DD>
|
|
Delete the character under the cursor, unless the cursor is at the
|
|
end of the line, in which case the character behind the cursor is
|
|
deleted.
|
|
<DT><B>quoted-insert (C-q, C-v)</B>
|
|
|
|
<DD>
|
|
Add the next character typed to the line verbatim. This is
|
|
how to insert characters like <B>C-q</B>, for example.
|
|
<DT><B>tab-insert (C-v TAB)</B>
|
|
|
|
<DD>
|
|
Insert a tab character.
|
|
<DT><B>self-insert (a, b, A, 1, !, ...)</B>
|
|
|
|
<DD>
|
|
Insert the character typed.
|
|
<DT><B>transpose-chars (C-t)</B>
|
|
|
|
<DD>
|
|
Drag the character before point forward over the character at point,
|
|
moving point forward as well.
|
|
If point is at the end of the line, then this transposes
|
|
the two characters before point.
|
|
Negative arguments have no effect.
|
|
<DT><B>transpose-words (M-t)</B>
|
|
|
|
<DD>
|
|
Drag the word before point past the word after point,
|
|
moving point over that word as well.
|
|
If point is at the end of the line, this transposes
|
|
the last two words on the line.
|
|
<DT><B>upcase-word (M-u)</B>
|
|
|
|
<DD>
|
|
Uppercase the current (or following) word. With a negative argument,
|
|
uppercase the previous word, but do not move point.
|
|
<DT><B>downcase-word (M-l)</B>
|
|
|
|
<DD>
|
|
Lowercase the current (or following) word. With a negative argument,
|
|
lowercase the previous word, but do not move point.
|
|
<DT><B>capitalize-word (M-c)</B>
|
|
|
|
<DD>
|
|
Capitalize the current (or following) word. With a negative argument,
|
|
capitalize the previous word, but do not move point.
|
|
<DT><B>overwrite-mode</B>
|
|
|
|
<DD>
|
|
Toggle overwrite mode. With an explicit positive numeric argument,
|
|
switches to overwrite mode. With an explicit non-positive numeric
|
|
argument, switches to insert mode. This command affects only
|
|
<B>emacs</B> mode; <B>vi</B> mode does overwrite differently.
|
|
Each call to <I>readline()</I> starts in insert mode.
|
|
In overwrite mode, characters bound to <B>self-insert</B> replace
|
|
the text at point rather than pushing the text to the right.
|
|
Characters bound to <B>backward-delete-char</B> replace the character
|
|
before point with a space. By default, this command is unbound.
|
|
|
|
</DL>
|
|
<A NAME="lbCQ"> </A>
|
|
<H4>Killing and Yanking</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>kill-line (C-k)</B>
|
|
|
|
<DD>
|
|
Kill the text from point to the end of the line.
|
|
<DT><B>backward-kill-line (C-x Rubout)</B>
|
|
|
|
<DD>
|
|
Kill backward to the beginning of the line.
|
|
<DT><B>unix-line-discard (C-u)</B>
|
|
|
|
<DD>
|
|
Kill backward from point to the beginning of the line.
|
|
The killed text is saved on the kill-ring.
|
|
|
|
<DT><B>kill-whole-line</B>
|
|
|
|
<DD>
|
|
Kill all characters on the current line, no matter where point is.
|
|
<DT><B>kill-word (M-d)</B>
|
|
|
|
<DD>
|
|
Kill from point to the end of the current word, or if between
|
|
words, to the end of the next word.
|
|
Word boundaries are the same as those used by <B>forward-word</B>.
|
|
<DT><B>backward-kill-word (M-Rubout)</B>
|
|
|
|
<DD>
|
|
Kill the word behind point.
|
|
Word boundaries are the same as those used by <B>backward-word</B>.
|
|
<DT><B>shell-kill-word</B>
|
|
|
|
<DD>
|
|
Kill from point to the end of the current word, or if between
|
|
words, to the end of the next word.
|
|
Word boundaries are the same as those used by <B>shell-forward-word</B>.
|
|
<DT><B>shell-backward-kill-word</B>
|
|
|
|
<DD>
|
|
Kill the word behind point.
|
|
Word boundaries are the same as those used by <B>shell-backward-word</B>.
|
|
<DT><B>unix-word-rubout (C-w)</B>
|
|
|
|
<DD>
|
|
Kill the word behind point, using white space as a word boundary.
|
|
The killed text is saved on the kill-ring.
|
|
<DT><B>unix-filename-rubout</B>
|
|
|
|
<DD>
|
|
Kill the word behind point, using white space and the slash character
|
|
as the word boundaries.
|
|
The killed text is saved on the kill-ring.
|
|
<DT><B>delete-horizontal-space (M-\)</B>
|
|
|
|
<DD>
|
|
Delete all spaces and tabs around point.
|
|
<DT><B>kill-region</B>
|
|
|
|
<DD>
|
|
Kill the text in the current region.
|
|
<DT><B>copy-region-as-kill</B>
|
|
|
|
<DD>
|
|
Copy the text in the region to the kill buffer.
|
|
<DT><B>copy-backward-word</B>
|
|
|
|
<DD>
|
|
Copy the word before point to the kill buffer.
|
|
The word boundaries are the same as <B>backward-word</B>.
|
|
<DT><B>copy-forward-word</B>
|
|
|
|
<DD>
|
|
Copy the word following point to the kill buffer.
|
|
The word boundaries are the same as <B>forward-word</B>.
|
|
<DT><B>yank (C-y)</B>
|
|
|
|
<DD>
|
|
Yank the top of the kill ring into the buffer at point.
|
|
<DT><B>yank-pop (M-y)</B>
|
|
|
|
<DD>
|
|
Rotate the kill ring, and yank the new top. Only works following
|
|
<B>yank</B>
|
|
|
|
or
|
|
<B>yank-pop</B>.
|
|
|
|
|
|
</DL>
|
|
<A NAME="lbCR"> </A>
|
|
<H4>Numeric Arguments</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>digit-argument (M-0, M-1, ..., M--)</B>
|
|
|
|
<DD>
|
|
Add this digit to the argument already accumulating, or start a new
|
|
argument. M-- starts a negative argument.
|
|
<DT><B>universal-argument</B>
|
|
|
|
<DD>
|
|
This is another way to specify an argument.
|
|
If this command is followed by one or more digits, optionally with a
|
|
leading minus sign, those digits define the argument.
|
|
If the command is followed by digits, executing
|
|
<B>universal-argument</B>
|
|
|
|
again ends the numeric argument, but is otherwise ignored.
|
|
As a special case, if this command is immediately followed by a
|
|
character that is neither a digit nor minus sign, the argument count
|
|
for the next command is multiplied by four.
|
|
The argument count is initially one, so executing this function the
|
|
first time makes the argument count four, a second time makes the
|
|
argument count sixteen, and so on.
|
|
|
|
</DL>
|
|
<A NAME="lbCS"> </A>
|
|
<H4>Completing</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>complete (TAB)</B>
|
|
|
|
<DD>
|
|
Attempt to perform completion on the text before point.
|
|
<B>Bash</B>
|
|
|
|
attempts completion treating the text as a variable (if the
|
|
text begins with <B>$</B>), username (if the text begins with
|
|
<B>~</B>), hostname (if the text begins with <B>@</B>), or
|
|
command (including aliases and functions) in turn. If none
|
|
of these produces a match, filename completion is attempted.
|
|
<DT><B>possible-completions (M-?)</B>
|
|
|
|
<DD>
|
|
List the possible completions of the text before point.
|
|
<DT><B>insert-completions (M-*)</B>
|
|
|
|
<DD>
|
|
Insert all completions of the text before point
|
|
that would have been generated by
|
|
<B>possible-completions</B>.
|
|
<DT><B>menu-complete</B>
|
|
|
|
<DD>
|
|
Similar to <B>complete</B>, but replaces the word to be completed
|
|
with a single match from the list of possible completions.
|
|
Repeated execution of <B>menu-complete</B> steps through the list
|
|
of possible completions, inserting each match in turn.
|
|
At the end of the list of completions, the bell is rung
|
|
(subject to the setting of <B>bell-style</B>)
|
|
and the original text is restored.
|
|
An argument of <I>n</I> moves <I>n</I> positions forward in the list
|
|
of matches; a negative argument may be used to move backward
|
|
through the list.
|
|
This command is intended to be bound to <B>TAB</B>, but is unbound
|
|
by default.
|
|
<DT><B>menu-complete-backward</B>
|
|
|
|
<DD>
|
|
Identical to <B>menu-complete</B>, but moves backward through the list
|
|
of possible completions, as if <B>menu-complete</B> had been given a
|
|
negative argument. This command is unbound by default.
|
|
<DT><B>delete-char-or-list</B>
|
|
|
|
<DD>
|
|
Deletes the character under the cursor if not at the beginning or
|
|
end of the line (like <B>delete-char</B>).
|
|
If at the end of the line, behaves identically to
|
|
<B>possible-completions</B>.
|
|
This command is unbound by default.
|
|
<DT><B>complete-filename (M-/)</B>
|
|
|
|
<DD>
|
|
Attempt filename completion on the text before point.
|
|
<DT><B>possible-filename-completions (C-x /)</B>
|
|
|
|
<DD>
|
|
List the possible completions of the text before point,
|
|
treating it as a filename.
|
|
<DT><B>complete-username (M-~)</B>
|
|
|
|
<DD>
|
|
Attempt completion on the text before point, treating
|
|
it as a username.
|
|
<DT><B>possible-username-completions (C-x ~)</B>
|
|
|
|
<DD>
|
|
List the possible completions of the text before point,
|
|
treating it as a username.
|
|
<DT><B>complete-variable (M-$)</B>
|
|
|
|
<DD>
|
|
Attempt completion on the text before point, treating
|
|
it as a shell variable.
|
|
<DT><B>possible-variable-completions (C-x $)</B>
|
|
|
|
<DD>
|
|
List the possible completions of the text before point,
|
|
treating it as a shell variable.
|
|
<DT><B>complete-hostname (M-@)</B>
|
|
|
|
<DD>
|
|
Attempt completion on the text before point, treating
|
|
it as a hostname.
|
|
<DT><B>possible-hostname-completions (C-x @)</B>
|
|
|
|
<DD>
|
|
List the possible completions of the text before point,
|
|
treating it as a hostname.
|
|
<DT><B>complete-command (M-!)</B>
|
|
|
|
<DD>
|
|
Attempt completion on the text before point, treating
|
|
it as a command name. Command completion attempts to
|
|
match the text against aliases, reserved words, shell
|
|
functions, shell builtins, and finally executable filenames,
|
|
in that order.
|
|
<DT><B>possible-command-completions (C-x !)</B>
|
|
|
|
<DD>
|
|
List the possible completions of the text before point,
|
|
treating it as a command name.
|
|
<DT><B>dynamic-complete-history (M-TAB)</B>
|
|
|
|
<DD>
|
|
Attempt completion on the text before point, comparing
|
|
the text against lines from the history list for possible
|
|
completion matches.
|
|
<DT><B>dabbrev-expand</B>
|
|
|
|
<DD>
|
|
Attempt menu completion on the text before point, comparing
|
|
the text against lines from the history list for possible
|
|
completion matches.
|
|
<DT><B>complete-into-braces (M-{)</B>
|
|
|
|
<DD>
|
|
Perform filename completion and insert the list of possible completions
|
|
enclosed within braces so the list is available to the shell (see
|
|
<B>Brace Expansion</B>
|
|
|
|
above).
|
|
|
|
</DL>
|
|
<A NAME="lbCT"> </A>
|
|
<H4>Keyboard Macros</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>start-kbd-macro (C-x ()</B>
|
|
|
|
<DD>
|
|
Begin saving the characters typed into the current keyboard macro.
|
|
<DT><B>end-kbd-macro (C-x ))</B>
|
|
|
|
<DD>
|
|
Stop saving the characters typed into the current keyboard macro
|
|
and store the definition.
|
|
<DT><B>call-last-kbd-macro (C-x e)</B>
|
|
|
|
<DD>
|
|
Re-execute the last keyboard macro defined, by making the characters
|
|
in the macro appear as if typed at the keyboard.
|
|
<DT><B>print-last-kbd-macro ()</B>
|
|
|
|
<DD>
|
|
Print the last keyboard macro defined in a format suitable for the
|
|
<I>inputrc</I> file.
|
|
|
|
</DL>
|
|
<A NAME="lbCU"> </A>
|
|
<H4>Miscellaneous</H4>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>re-read-init-file (C-x C-r)</B>
|
|
|
|
<DD>
|
|
Read in the contents of the <I>inputrc</I> file, and incorporate
|
|
any bindings or variable assignments found there.
|
|
<DT><B>abort (C-g)</B>
|
|
|
|
<DD>
|
|
Abort the current editing command and
|
|
ring the terminal's bell (subject to the setting of
|
|
<B>bell-style</B>).
|
|
|
|
<DT><B>do-lowercase-version (M-A, M-B, M-</B><I>x</I>, ...)
|
|
|
|
<DD>
|
|
If the metafied character <I>x</I> is uppercase, run the command
|
|
that is bound to the corresponding metafied lowercase character.
|
|
The behavior is undefined if <I>x</I> is already lowercase.
|
|
<DT><B>prefix-meta (ESC)</B>
|
|
|
|
<DD>
|
|
Metafy the next character typed.
|
|
<FONT SIZE=-1><B>ESC</B>
|
|
|
|
</FONT>
|
|
<B>f</B>
|
|
|
|
is equivalent to
|
|
<B>Meta-f</B>.
|
|
|
|
<DT><B>undo (C-_, C-x C-u)</B>
|
|
|
|
<DD>
|
|
Incremental undo, separately remembered for each line.
|
|
<DT><B>revert-line (M-r)</B>
|
|
|
|
<DD>
|
|
Undo all changes made to this line. This is like executing the
|
|
<B>undo</B>
|
|
|
|
command enough times to return the line to its initial state.
|
|
<DT><B>tilde-expand (M-&)</B>
|
|
|
|
<DD>
|
|
Perform tilde expansion on the current word.
|
|
<DT><B>set-mark (C-@, M-<space>)</B>
|
|
|
|
<DD>
|
|
Set the mark to the point. If a
|
|
numeric argument is supplied, the mark is set to that position.
|
|
<DT><B>exchange-point-and-mark (C-x C-x)</B>
|
|
|
|
<DD>
|
|
Swap the point with the mark. The current cursor position is set to
|
|
the saved position, and the old cursor position is saved as the mark.
|
|
<DT><B>character-search (C-])</B>
|
|
|
|
<DD>
|
|
A character is read and point is moved to the next occurrence of that
|
|
character. A negative argument searches for previous occurrences.
|
|
<DT><B>character-search-backward (M-C-])</B>
|
|
|
|
<DD>
|
|
A character is read and point is moved to the previous occurrence of that
|
|
character. A negative argument searches for subsequent occurrences.
|
|
<DT><B>skip-csi-sequence</B>
|
|
|
|
<DD>
|
|
Read enough characters to consume a multi-key sequence such as those
|
|
defined for keys like Home and End. Such sequences begin with a
|
|
Control Sequence Indicator (CSI), usually ESC-[. If this sequence is
|
|
bound to "\[", keys producing such sequences will have no effect
|
|
unless explicitly bound to a readline command, instead of inserting
|
|
stray characters into the editing buffer. This is unbound by default,
|
|
but usually bound to ESC-[.
|
|
<DT><B>insert-comment (M-#)</B>
|
|
|
|
<DD>
|
|
Without a numeric argument, the value of the readline
|
|
<B>comment-begin</B>
|
|
|
|
variable is inserted at the beginning of the current line.
|
|
If a numeric argument is supplied, this command acts as a toggle: if
|
|
the characters at the beginning of the line do not match the value
|
|
of <B>comment-begin</B>, the value is inserted, otherwise
|
|
the characters in <B>comment-begin</B> are deleted from the beginning of
|
|
the line.
|
|
In either case, the line is accepted as if a newline had been typed.
|
|
The default value of
|
|
<B>comment-begin</B> causes this command to make the current line
|
|
a shell comment.
|
|
If a numeric argument causes the comment character to be removed, the line
|
|
will be executed by the shell.
|
|
<DT><B>spell-correct-word (C-x s)</B>
|
|
|
|
<DD>
|
|
Perform spelling correction on the current word, treating it as a directory
|
|
or filename, in the same way as the <B>cdspell</B> shell option.
|
|
Word boundaries are the same as those used by <B>shell-forward-word</B>.
|
|
<DT><B>glob-complete-word (M-g)</B>
|
|
|
|
<DD>
|
|
The word before point is treated as a pattern for pathname expansion,
|
|
with an asterisk implicitly appended. This pattern is used to
|
|
generate a list of matching filenames for possible completions.
|
|
<DT><B>glob-expand-word (C-x *)</B>
|
|
|
|
<DD>
|
|
The word before point is treated as a pattern for pathname expansion,
|
|
and the list of matching filenames is inserted, replacing the word.
|
|
If a numeric argument is supplied, an asterisk is appended before
|
|
pathname expansion.
|
|
<DT><B>glob-list-expansions (C-x g)</B>
|
|
|
|
<DD>
|
|
The list of expansions that would have been generated by
|
|
<B>glob-expand-word</B>
|
|
|
|
is displayed, and the line is redrawn.
|
|
If a numeric argument is supplied, an asterisk is appended before
|
|
pathname expansion.
|
|
<DT><B>dump-functions</B>
|
|
|
|
<DD>
|
|
Print all of the functions and their key bindings to the
|
|
readline output stream. If a numeric argument is supplied,
|
|
the output is formatted in such a way that it can be made part
|
|
of an <I>inputrc</I> file.
|
|
<DT><B>dump-variables</B>
|
|
|
|
<DD>
|
|
Print all of the settable readline variables and their values to the
|
|
readline output stream. If a numeric argument is supplied,
|
|
the output is formatted in such a way that it can be made part
|
|
of an <I>inputrc</I> file.
|
|
<DT><B>dump-macros</B>
|
|
|
|
<DD>
|
|
Print all of the readline key sequences bound to macros and the
|
|
strings they output. If a numeric argument is supplied,
|
|
the output is formatted in such a way that it can be made part
|
|
of an <I>inputrc</I> file.
|
|
<DT><B>display-shell-version (C-x C-v)</B>
|
|
|
|
<DD>
|
|
Display version information about the current instance of
|
|
<B>bash</B>.
|
|
|
|
|
|
</DL>
|
|
<A NAME="lbCV"> </A>
|
|
<H4>Programmable Completion</H4>
|
|
|
|
When word completion is attempted for an argument to a command for
|
|
which a completion specification (a <I>compspec</I>) has been defined
|
|
using the <B>complete</B> builtin (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below), the programmable completion facilities are invoked.
|
|
<P>
|
|
|
|
First, the command name is identified.
|
|
If the command word is the empty string (completion attempted at the
|
|
beginning of an empty line), any compspec defined with
|
|
the <B>-E</B> option to <B>complete</B> is used.
|
|
If a compspec has been defined for that command, the
|
|
compspec is used to generate the list of possible completions for the word.
|
|
If the command word is a full pathname, a compspec for the full
|
|
pathname is searched for first.
|
|
If no compspec is found for the full pathname, an attempt is made to
|
|
find a compspec for the portion following the final slash.
|
|
If those searches do not result in a compspec, any compspec defined with
|
|
the <B>-D</B> option to <B>complete</B> is used as the default.
|
|
If there is no default compspec, <B>bash</B> attempts alias expansion
|
|
on the command word as a final resort, and attempts to find a compspec
|
|
for the command word from any successful expansion.
|
|
<P>
|
|
|
|
Once a compspec has been found, it is used to generate the list of
|
|
matching words.
|
|
If a compspec is not found, the default <B>bash</B> completion as
|
|
described above under <B>Completing</B> is performed.
|
|
<P>
|
|
|
|
First, the actions specified by the compspec are used.
|
|
Only matches which are prefixed by the word being completed are
|
|
returned.
|
|
When the
|
|
<B>-f</B>
|
|
|
|
or
|
|
<B>-d</B>
|
|
|
|
option is used for filename or directory name completion, the shell
|
|
variable
|
|
<FONT SIZE=-1><B>FIGNORE</B>
|
|
|
|
</FONT>
|
|
is used to filter the matches.
|
|
<P>
|
|
|
|
Any completions specified by a pathname expansion pattern to the
|
|
<B>-G</B> option are generated next.
|
|
The words generated by the pattern need not match the word
|
|
being completed.
|
|
The
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
shell variable is not used to filter the matches, but the
|
|
<FONT SIZE=-1><B>FIGNORE</B>
|
|
|
|
</FONT>
|
|
variable is used.
|
|
<P>
|
|
|
|
Next, the string specified as the argument to the <B>-W</B> option
|
|
is considered.
|
|
The string is first split using the characters in the
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
special variable as delimiters.
|
|
Shell quoting is honored.
|
|
Each word is then expanded using
|
|
brace expansion, tilde expansion, parameter and variable expansion,
|
|
command substitution, and arithmetic expansion,
|
|
as described above under
|
|
<FONT SIZE=-1><B>EXPANSION</B>.
|
|
|
|
</FONT>
|
|
The results are split using the rules described above under
|
|
<B>Word Splitting</B>.
|
|
The results of the expansion are prefix-matched against the word being
|
|
completed, and the matching words become the possible completions.
|
|
<P>
|
|
|
|
After these matches have been generated, any shell function or command
|
|
specified with the <B>-F</B> and <B>-C</B> options is invoked.
|
|
When the command or function is invoked, the
|
|
<FONT SIZE=-1><B>COMP_LINE</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>COMP_POINT</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>COMP_KEY</B>,
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>COMP_TYPE</B>
|
|
|
|
</FONT>
|
|
variables are assigned values as described above under
|
|
<B>Shell Variables</B>.
|
|
If a shell function is being invoked, the
|
|
<FONT SIZE=-1><B>COMP_WORDS</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>COMP_CWORD</B>
|
|
|
|
</FONT>
|
|
variables are also set.
|
|
When the function or command is invoked,
|
|
the first argument (<B>$1</B>) is the name of the command whose arguments are
|
|
being completed,
|
|
the second argument (<B>$2</B>) is the word being completed,
|
|
and the third argument (<B>$3</B>) is the word preceding the word being
|
|
completed on the current command line.
|
|
No filtering of the generated completions against the word being completed
|
|
is performed; the function or command has complete freedom in generating
|
|
the matches.
|
|
<P>
|
|
|
|
Any function specified with <B>-F</B> is invoked first.
|
|
The function may use any of the shell facilities, including the
|
|
<B>compgen</B> builtin described below, to generate the matches.
|
|
It must put the possible completions in the
|
|
<FONT SIZE=-1><B>COMPREPLY</B>
|
|
|
|
</FONT>
|
|
array variable, one per array element.
|
|
<P>
|
|
|
|
Next, any command specified with the <B>-C</B> option is invoked
|
|
in an environment equivalent to command substitution.
|
|
It should print a list of completions, one per line, to the
|
|
standard output.
|
|
Backslash may be used to escape a newline, if necessary.
|
|
<P>
|
|
|
|
After all of the possible completions are generated, any filter
|
|
specified with the <B>-X</B> option is applied to the list.
|
|
The filter is a pattern as used for pathname expansion; a <B>&</B>
|
|
in the pattern is replaced with the text of the word being completed.
|
|
A literal <B>&</B> may be escaped with a backslash; the backslash
|
|
is removed before attempting a match.
|
|
Any completion that matches the pattern will be removed from the list.
|
|
A leading <B>!</B> negates the pattern; in this case any completion
|
|
not matching the pattern will be removed.
|
|
If the
|
|
<B>nocasematch</B>
|
|
|
|
shell option is enabled, the match is performed without regard to the case
|
|
of alphabetic characters.
|
|
<P>
|
|
|
|
Finally, any prefix and suffix specified with the <B>-P</B> and <B>-S</B>
|
|
options are added to each member of the completion list, and the result is
|
|
returned to the readline completion code as the list of possible
|
|
completions.
|
|
<P>
|
|
|
|
If the previously-applied actions do not generate any matches, and the
|
|
<B>-o dirnames</B> option was supplied to <B>complete</B> when the
|
|
compspec was defined, directory name completion is attempted.
|
|
<P>
|
|
|
|
If the <B>-o plusdirs</B> option was supplied to <B>complete</B> when the
|
|
compspec was defined, directory name completion is attempted and any
|
|
matches are added to the results of the other actions.
|
|
<P>
|
|
|
|
By default, if a compspec is found, whatever it generates is returned
|
|
to the completion code as the full set of possible completions.
|
|
The default <B>bash</B> completions are not attempted, and the readline
|
|
default of filename completion is disabled.
|
|
If the <B>-o bashdefault</B> option was supplied to <B>complete</B> when
|
|
the compspec was defined, the <B>bash</B> default completions are attempted
|
|
if the compspec generates no matches.
|
|
If the <B>-o default</B> option was supplied to <B>complete</B> when the
|
|
compspec was defined, readline's default completion will be performed
|
|
if the compspec (and, if attempted, the default <B>bash</B> completions)
|
|
generate no matches.
|
|
<P>
|
|
|
|
When a compspec indicates that directory name completion is desired,
|
|
the programmable completion functions force readline to append a slash
|
|
to completed names which are symbolic links to directories, subject to
|
|
the value of the <B>mark-directories</B> readline variable, regardless
|
|
of the setting of the <B>mark-symlinked-directories</B> readline variable.
|
|
<P>
|
|
|
|
There is some support for dynamically modifying completions. This is
|
|
most useful when used in combination with a default completion specified
|
|
with <B>complete -D</B>.
|
|
It's possible for shell functions executed as completion
|
|
handlers to indicate that completion should be retried by returning an
|
|
exit status of 124. If a shell function returns 124, and changes
|
|
the compspec associated with the command on which completion is being
|
|
attempted (supplied as the first argument when the function is executed),
|
|
programmable completion restarts from the beginning, with an
|
|
attempt to find a new compspec for that command. This allows a set of
|
|
completions to be built dynamically as completion is attempted, rather than
|
|
being loaded all at once.
|
|
<P>
|
|
|
|
For instance, assuming that there is a library of compspecs, each kept in a
|
|
file corresponding to the name of the command, the following default
|
|
completion function would load completions dynamically:
|
|
<P>
|
|
|
|
<TT>_completion_loader()
|
|
<BR>
|
|
|
|
{
|
|
<BR>
|
|
|
|
<TT> </TT>. "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124<BR>
|
|
<BR>
|
|
|
|
}
|
|
<BR>
|
|
|
|
complete -D -F _completion_loader -o bashdefault -o default
|
|
<BR>
|
|
|
|
</TT>
|
|
<A NAME="lbCW"> </A>
|
|
<H3>HISTORY</H3>
|
|
|
|
When the
|
|
<B>-o history</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin is enabled, the shell provides access to the
|
|
<I>command history</I>,
|
|
the list of commands previously typed.
|
|
The value of the
|
|
<FONT SIZE=-1><B>HISTSIZE</B>
|
|
|
|
</FONT>
|
|
variable is used as the
|
|
number of commands to save in a history list.
|
|
The text of the last
|
|
<FONT SIZE=-1><B>HISTSIZE</B>
|
|
|
|
</FONT>
|
|
commands (default 500) is saved. The shell
|
|
stores each command in the history list prior to parameter and
|
|
variable expansion (see
|
|
<FONT SIZE=-1><B>EXPANSION</B>
|
|
|
|
</FONT>
|
|
above) but after history expansion is performed, subject to the
|
|
values of the shell variables
|
|
<FONT SIZE=-1><B>HISTIGNORE</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>HISTCONTROL</B>.
|
|
|
|
</FONT>
|
|
<P>
|
|
|
|
On startup, the history is initialized from the file named by
|
|
the variable
|
|
<FONT SIZE=-1><B>HISTFILE</B>
|
|
|
|
</FONT>
|
|
(default <A HREF="file:~/.bash_history"><I>~/.bash_history</I></A>).
|
|
The file named by the value of
|
|
<FONT SIZE=-1><B>HISTFILE</B>
|
|
|
|
</FONT>
|
|
is truncated, if necessary, to contain no more than
|
|
the number of lines specified by the value of
|
|
<FONT SIZE=-1><B>HISTFILESIZE</B>.
|
|
|
|
</FONT>
|
|
If <B>HISTFILESIZE</B> is unset, or set to null, a non-numeric value,
|
|
or a numeric value less than zero, the history file is not truncated.
|
|
When the history file is read,
|
|
lines beginning with the history comment character followed immediately
|
|
by a digit are interpreted as timestamps for the following history line.
|
|
These timestamps are optionally displayed depending on the value of the
|
|
<FONT SIZE=-1><B>HISTTIMEFORMAT</B>
|
|
|
|
</FONT>
|
|
variable.
|
|
When a shell with history enabled exits, the last
|
|
<FONT SIZE=-1><B>$HISTSIZE</B>
|
|
|
|
</FONT>
|
|
lines are copied from the history list to
|
|
<FONT SIZE=-1><B>$HISTFILE</B>.
|
|
|
|
</FONT>
|
|
If the
|
|
<B>histappend</B>
|
|
|
|
shell option is enabled
|
|
(see the description of
|
|
<B>shopt</B>
|
|
|
|
under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below), the lines are appended to the history file,
|
|
otherwise the history file is overwritten.
|
|
If
|
|
<FONT SIZE=-1><B>HISTFILE</B>
|
|
|
|
</FONT>
|
|
is unset, or if the history file is unwritable, the history is
|
|
not saved.
|
|
If the
|
|
<FONT SIZE=-1><B>HISTTIMEFORMAT</B>
|
|
|
|
</FONT>
|
|
variable is set, time stamps are written to the history file, marked
|
|
with the history comment character, so
|
|
they may be preserved across shell sessions.
|
|
This uses the history comment character to distinguish timestamps from
|
|
other history lines.
|
|
After saving the history, the history file is truncated
|
|
to contain no more than
|
|
<FONT SIZE=-1><B>HISTFILESIZE</B>
|
|
|
|
</FONT>
|
|
lines. If
|
|
<FONT SIZE=-1><B>HISTFILESIZE</B>
|
|
|
|
</FONT>
|
|
is unset, or set to null, a non-numeric value,
|
|
or a numeric value less than zero, the history file is not truncated.
|
|
<P>
|
|
|
|
The builtin command
|
|
<B>fc</B>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below) may be used to list or edit and re-execute a portion of
|
|
the history list.
|
|
The
|
|
<B>history</B>
|
|
|
|
builtin may be used to display or modify the history list and
|
|
manipulate the history file.
|
|
When using command-line editing, search commands
|
|
are available in each editing mode that provide access to the
|
|
history list.
|
|
<P>
|
|
|
|
The shell allows control over which commands are saved on the history
|
|
list. The
|
|
<FONT SIZE=-1><B>HISTCONTROL</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>HISTIGNORE</B>
|
|
|
|
</FONT>
|
|
variables may be set to cause the shell to save only a subset of the
|
|
commands entered.
|
|
The
|
|
<B>cmdhist</B>
|
|
|
|
shell option, if enabled, causes the shell to attempt to save each
|
|
line of a multi-line command in the same history entry, adding
|
|
semicolons where necessary to preserve syntactic correctness.
|
|
The
|
|
<B>lithist</B>
|
|
|
|
shell option causes the shell to save the command with embedded newlines
|
|
instead of semicolons. See the description of the
|
|
<B>shopt</B>
|
|
|
|
builtin below under
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
for information on setting and unsetting shell options.
|
|
<A NAME="lbCX"> </A>
|
|
<H3>HISTORY EXPANSION</H3>
|
|
|
|
The shell supports a history expansion feature that
|
|
is similar to the history expansion in
|
|
<B>csh</B>.
|
|
|
|
This section describes what syntax features are available. This
|
|
feature is enabled by default for interactive shells, and can be
|
|
disabled using the
|
|
<B>+H</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin command (see
|
|
<FONT SIZE=-1><B>SHELL BUILTIN COMMANDS</B>
|
|
|
|
</FONT>
|
|
below). Non-interactive shells do not perform history expansion
|
|
by default.
|
|
<P>
|
|
|
|
History expansions introduce words from the history list into
|
|
the input stream, making it easy to repeat commands, insert the
|
|
arguments to a previous command into the current input line, or
|
|
fix errors in previous commands quickly.
|
|
<P>
|
|
|
|
History expansion is performed immediately after a complete line
|
|
is read, before the shell breaks it into words, and is performed
|
|
on each line individually without taking quoting on previous lines into
|
|
account.
|
|
It takes place in two parts.
|
|
The first is to determine which line from the history list
|
|
to use during substitution.
|
|
The second is to select portions of that line for inclusion into
|
|
the current one.
|
|
The line selected from the history is the <I>event</I>,
|
|
and the portions of that line that are acted upon are <I>words</I>.
|
|
Various <I>modifiers</I> are available to manipulate the selected words.
|
|
The line is broken into words in the same fashion as when reading input,
|
|
so that several <I>metacharacter</I>-separated words surrounded by
|
|
quotes are considered one word.
|
|
History expansions are introduced by the appearance of the
|
|
history expansion character, which is <B>!</B> by default.
|
|
Only backslash (<B>\</B>) and single quotes can quote
|
|
the history expansion character, but the history expansion character is
|
|
also treated as quoted if it immediately precedes the closing double quote
|
|
in a double-quoted string.
|
|
<P>
|
|
|
|
Several characters inhibit history expansion if found immediately
|
|
following the history expansion character, even if it is unquoted:
|
|
space, tab, newline, carriage return, and <B>=</B>.
|
|
If the <B>extglob</B> shell option is enabled, <B>(</B> will also
|
|
inhibit expansion.
|
|
<P>
|
|
|
|
Several shell options settable with the
|
|
<B>shopt</B>
|
|
|
|
builtin may be used to tailor the behavior of history expansion.
|
|
If the
|
|
<B>histverify</B>
|
|
|
|
shell option is enabled (see the description of the
|
|
<B>shopt</B>
|
|
|
|
builtin below), and
|
|
<B>readline</B>
|
|
|
|
is being used, history substitutions are not immediately passed to
|
|
the shell parser.
|
|
Instead, the expanded line is reloaded into the
|
|
<B>readline</B>
|
|
|
|
editing buffer for further modification.
|
|
If
|
|
<B>readline</B>
|
|
|
|
is being used, and the
|
|
<B>histreedit</B>
|
|
|
|
shell option is enabled, a failed history substitution will be reloaded
|
|
into the
|
|
<B>readline</B>
|
|
|
|
editing buffer for correction.
|
|
The
|
|
<B>-p</B>
|
|
|
|
option to the
|
|
<B>history</B>
|
|
|
|
builtin command may be used to see what a history expansion will
|
|
do before using it.
|
|
The
|
|
<B>-s</B>
|
|
|
|
option to the
|
|
<B>history</B>
|
|
|
|
builtin may be used to add commands to the end of the history list
|
|
without actually executing them, so that they are available for
|
|
subsequent recall.
|
|
<P>
|
|
|
|
The shell allows control of the various characters used by the
|
|
history expansion mechanism (see the description of
|
|
<B>histchars</B>
|
|
|
|
above under
|
|
<B>Shell Variables</B>).
|
|
|
|
The shell uses
|
|
the history comment character to mark history timestamps when
|
|
writing the history file.
|
|
<A NAME="lbCY"> </A>
|
|
<H4>Event Designators</H4>
|
|
|
|
An event designator is a reference to a command line entry in the
|
|
history list.
|
|
Unless the reference is absolute, events are relative to the current
|
|
position in the history list.
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>!</B>
|
|
|
|
<DD>
|
|
Start a history substitution, except when followed by a
|
|
<B>blank</B>,
|
|
|
|
newline, carriage return, =
|
|
or ( (when the <B>extglob</B> shell option is enabled using
|
|
the <B>shopt</B> builtin).
|
|
<DT><B>!</B><I>n</I>
|
|
|
|
<DD>
|
|
Refer to command line
|
|
<I>n</I>.
|
|
|
|
<DT><B>!-</B><I>n</I>
|
|
|
|
<DD>
|
|
Refer to the current command minus
|
|
<I>n</I>.
|
|
|
|
<DT><B>!!</B>
|
|
|
|
<DD>
|
|
Refer to the previous command. This is a synonym for `!-1'.
|
|
<DT><B>!</B><I>string</I>
|
|
|
|
<DD>
|
|
Refer to the most recent command preceding the current position in the
|
|
history list starting with
|
|
<I>string</I>.
|
|
|
|
<DT><B>!?</B><I>string</I><B>[?]</B>
|
|
|
|
<DD>
|
|
Refer to the most recent command preceding the current position in the
|
|
history list containing
|
|
<I>string</I>.
|
|
|
|
The trailing <B>?</B> may be omitted if
|
|
<I>string</I>
|
|
|
|
is followed immediately by a newline.
|
|
If <I>string</I> is missing, the string from the most recent search is used;
|
|
it is an error if there is no previous search string.
|
|
<DT><B></B><FONT SIZE=+2><B>^</B></FONT><B></B><I>string1</I><FONT SIZE=+2>^</FONT><I>string2</I><FONT SIZE=+2>^</FONT>
|
|
|
|
<DD>
|
|
Quick substitution. Repeat the previous command, replacing
|
|
<I>string1</I>
|
|
|
|
with
|
|
<I>string2</I>.
|
|
|
|
Equivalent to
|
|
``!!:s<FONT SIZE=+2>^</FONT><I>string1</I><FONT SIZE=+2>^</FONT><I>string2</I><FONT SIZE=+2>^</FONT>''
|
|
(see <B>Modifiers</B> below).
|
|
<DT><B>!#</B>
|
|
|
|
<DD>
|
|
The entire command line typed so far.
|
|
|
|
</DL>
|
|
<A NAME="lbCZ"> </A>
|
|
<H4>Word Designators</H4>
|
|
|
|
Word designators are used to select desired words from the event.
|
|
A
|
|
<B>:</B>
|
|
|
|
separates the event specification from the word designator.
|
|
It may be omitted if the word designator begins with a
|
|
<B>^</B>,
|
|
|
|
<B>$</B>,
|
|
|
|
<B>*</B>,
|
|
|
|
<B>-</B>,
|
|
|
|
or
|
|
<B>%</B>.
|
|
|
|
Words are numbered from the beginning of the line,
|
|
with the first word being denoted by 0 (zero).
|
|
Words are inserted into the current line separated by single spaces.
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>0 (zero)</B>
|
|
|
|
<DD>
|
|
The zeroth word. For the shell, this is the command
|
|
word.
|
|
<DT><I>n</I>
|
|
|
|
<DD>
|
|
The <I>n</I>th word.
|
|
<DT><B>^</B>
|
|
|
|
<DD>
|
|
The first argument. That is, word 1.
|
|
<DT><B>$</B>
|
|
|
|
<DD>
|
|
The last word. This is usually the last argument, but will expand to the
|
|
zeroth word if there is only one word in the line.
|
|
<DT><B>%</B>
|
|
|
|
<DD>
|
|
The first word matched by the most recent `?<I>string</I>?' search,
|
|
if the search string begins with a character that is part of a word.
|
|
<DT><I>x</I><B>-</B>y
|
|
|
|
<DD>
|
|
A range of words; `-<I>y</I>' abbreviates `0-<I>y</I>'.
|
|
<DT><B>*</B>
|
|
|
|
<DD>
|
|
All of the words but the zeroth. This is a synonym
|
|
for `<I>1-$</I>'. It is not an error to use
|
|
<B>*</B>
|
|
|
|
if there is just one
|
|
word in the event; the empty string is returned in that case.
|
|
<DT><B>x*</B>
|
|
|
|
<DD>
|
|
Abbreviates <I>x-$</I>.
|
|
<DT><B>x-</B>
|
|
|
|
<DD>
|
|
Abbreviates <I>x-$</I> like <B>x*</B>, but omits the last word.
|
|
If <B>x</B> is missing, it defaults to 0.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If a word designator is supplied without an event specification, the
|
|
previous command is used as the event.
|
|
<A NAME="lbDA"> </A>
|
|
<H4>Modifiers</H4>
|
|
|
|
After the optional word designator, there may appear a sequence of
|
|
one or more of the following modifiers, each preceded by a `:'.
|
|
These modify, or edit, the word or words selected from the history event.
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>h</B>
|
|
|
|
<DD>
|
|
Remove a trailing filename component, leaving only the head.
|
|
<DT><B>t</B>
|
|
|
|
<DD>
|
|
Remove all leading filename components, leaving the tail.
|
|
<DT><B>r</B>
|
|
|
|
<DD>
|
|
Remove a trailing suffix of the form <I>.xxx</I>, leaving the
|
|
basename.
|
|
<DT><B>e</B>
|
|
|
|
<DD>
|
|
Remove all but the trailing suffix.
|
|
<DT><B>p</B>
|
|
|
|
<DD>
|
|
Print the new command but do not execute it.
|
|
<DT><B>q</B>
|
|
|
|
<DD>
|
|
Quote the substituted words, escaping further substitutions.
|
|
<DT><B>x</B>
|
|
|
|
<DD>
|
|
Quote the substituted words as with
|
|
<B>q</B>,
|
|
|
|
but break into words at
|
|
<B>blanks</B>
|
|
|
|
and newlines.
|
|
The <B>q</B> and <B>x</B> modifiers are mutually exclusive; the last one
|
|
supplied is used.
|
|
<DT><B>s/</B><I>old</I>/<I>new</I>/
|
|
|
|
<DD>
|
|
Substitute
|
|
<I>new</I>
|
|
|
|
for the first occurrence of
|
|
<I>old</I>
|
|
|
|
in the event line.
|
|
Any character may be used as the delimiter in place of /.
|
|
The final delimiter is optional if it is the last character of the
|
|
event line.
|
|
The delimiter may be quoted in
|
|
<I>old</I>
|
|
|
|
and
|
|
<I>new</I>
|
|
|
|
with a single backslash. If & appears in
|
|
<I>new</I>,
|
|
|
|
it is replaced by
|
|
<I>old</I>.
|
|
|
|
A single backslash will quote the &.
|
|
If
|
|
<I>old</I>
|
|
|
|
is null, it is set to the last
|
|
<I>old</I>
|
|
|
|
substituted, or, if no previous history substitutions took place,
|
|
the last
|
|
<I>string</I>
|
|
|
|
in a
|
|
<B>!?</B><I>string</I><B>[?]</B>
|
|
|
|
search.
|
|
If
|
|
<I>new</I>
|
|
|
|
is null, each matching
|
|
<I>old</I>
|
|
|
|
is deleted.
|
|
<DT><B>&</B>
|
|
|
|
<DD>
|
|
Repeat the previous substitution.
|
|
<DT><B>g</B>
|
|
|
|
<DD>
|
|
Cause changes to be applied over the entire event line. This is
|
|
used in conjunction with `<B>:s</B>' (e.g., `<B>:gs/</B><I>old</I>/<I>new</I>/')
|
|
or `<B>:&</B>'. If used with
|
|
`<B>:s</B>', any delimiter can be used
|
|
in place of /, and the final delimiter is optional
|
|
if it is the last character of the event line.
|
|
An <B>a</B> may be used as a synonym for <B>g</B>.
|
|
<DT><B>G</B>
|
|
|
|
<DD>
|
|
Apply the following `<B>s</B>' or `<B>&</B>' modifier once to each word
|
|
in the event line.
|
|
|
|
</DL>
|
|
<A NAME="lbDB"> </A>
|
|
<H3>SHELL BUILTIN COMMANDS</H3>
|
|
|
|
|
|
|
|
<P>
|
|
|
|
Unless otherwise noted, each builtin command documented in this
|
|
section as accepting options preceded by
|
|
<B>-</B>
|
|
|
|
accepts
|
|
<B>--</B>
|
|
|
|
to signify the end of the options.
|
|
The <B>:</B>, <B>true</B>, <B>false</B>, and <B>test</B>/<B>[</B> builtins
|
|
do not accept options and do not treat <B>--</B> specially.
|
|
The <B>exit</B>, <B>logout</B>, <B>return</B>,
|
|
<B>break</B>, <B>continue</B>, <B>let</B>,
|
|
and <B>shift</B> builtins accept and process arguments beginning with
|
|
<B>-</B> without requiring <B>--</B>.
|
|
Other builtins that accept arguments but are not specified as accepting
|
|
options interpret arguments beginning with <B>-</B> as invalid options and
|
|
require <B>--</B> to prevent this interpretation.
|
|
<P>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>:</B> [<I>arguments</I>]<DD>
|
|
|
|
No effect; the command does nothing beyond expanding
|
|
<I>arguments</I>
|
|
|
|
and performing any specified
|
|
redirections.
|
|
The return status is zero.
|
|
<DT><B> . </B> <I>filename</I> [<I>arguments</I>]<DD>
|
|
|
|
<DT><B>source</B> <I>filename</I> [<I>arguments</I>]<DD>
|
|
|
|
Read and execute commands from
|
|
<I>filename</I>
|
|
|
|
in the current
|
|
shell environment and return the exit status of the last command
|
|
executed from
|
|
<I>filename</I>.
|
|
|
|
If
|
|
<I>filename</I>
|
|
|
|
does not contain a slash, filenames in
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
are used to find the directory containing
|
|
<I>filename</I>,
|
|
|
|
but <I>filename</I> does not need to be executable.
|
|
The file searched for in
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
need not be executable.
|
|
When <B>bash</B> is not in <I>posix mode</I>, it searches
|
|
the current directory if no file is found in
|
|
<FONT SIZE=-1><B>PATH</B>.
|
|
|
|
</FONT>
|
|
If the
|
|
<B>sourcepath</B>
|
|
|
|
option to the
|
|
<B>shopt</B>
|
|
|
|
builtin command is turned off, the
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
is not searched.
|
|
If any <I>arguments</I> are supplied, they become the positional
|
|
parameters when <I>filename</I> is executed. Otherwise the positional
|
|
parameters are unchanged.
|
|
If the <B>-T</B> option is enabled, <B>.</B> inherits any trap on
|
|
<B>DEBUG</B>; if it is not, any <B>DEBUG</B> trap string is saved and
|
|
restored around the call to <B>.</B>, and <B>.</B> unsets the
|
|
<B>DEBUG</B> trap while it executes.
|
|
If <B>-T</B> is not set, and the sourced file changes
|
|
the <B>DEBUG</B> trap, the new value is retained when <B>.</B> completes.
|
|
The return status is the status of the last command exited within
|
|
the script (0 if no commands are executed), and false if
|
|
<I>filename</I>
|
|
|
|
is not found or cannot be read.
|
|
<DT><B>alias</B> [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD>
|
|
<B>Alias</B> with no arguments or with the
|
|
<B>-p</B>
|
|
|
|
option prints the list of aliases in the form
|
|
<B>alias</B> <I>name</I>=<I>value</I> on standard output.
|
|
When arguments are supplied, an alias is defined for
|
|
each <I>name</I> whose <I>value</I> is given.
|
|
A trailing space in <I>value</I> causes the next word to be
|
|
checked for alias substitution when the alias is expanded.
|
|
For each <I>name</I> in the argument list for which no <I>value</I>
|
|
is supplied, the name and value of the alias is printed.
|
|
<B>Alias</B> returns true unless a <I>name</I> is given for which
|
|
no alias has been defined.
|
|
<DT><B>bg</B> [<I>jobspec</I> ...]<DD>
|
|
Resume each suspended job <I>jobspec</I> in the background, as if it
|
|
had been started with
|
|
<B>&</B>.
|
|
|
|
If
|
|
<I>jobspec</I>
|
|
|
|
is not present, the shell's notion of the <I>current job</I> is used.
|
|
<B>bg</B>
|
|
|
|
<I>jobspec</I>
|
|
|
|
returns 0 unless run when job control is disabled or, when run with
|
|
job control enabled, any specified <I>jobspec</I> was not found
|
|
or was started without job control.
|
|
<DT><B>bind</B> [<B>-m</B> <I>keymap</I>] [<B>-lpsvPSVX</B>]<DD>
|
|
|
|
<DT><B>bind</B> [<B>-m</B> <I>keymap</I>] [<B>-q</B> <I>function</I>] [<B>-u</B> <I>function</I>] [<B>-r</B> <I>keyseq</I>]<DD>
|
|
<DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <B>-f</B> <I>filename</I><DD>
|
|
<DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <B>-x</B> <I>keyseq</I>:<I>shell-command</I><DD>
|
|
<DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <I>keyseq</I>:<I>function-name</I><DD>
|
|
<DT><B>bind</B> [<B>-m</B> <I>keymap</I>] <I>keyseq</I>:<I>readline-command</I><DD>
|
|
<DT><B>bind</B> <I>readline-command-line</I><DD>
|
|
|
|
Display current
|
|
<B>readline</B>
|
|
|
|
key and function bindings, bind a key sequence to a
|
|
<B>readline</B>
|
|
|
|
function or macro, or set a
|
|
<B>readline</B>
|
|
|
|
variable.
|
|
Each non-option argument is a command as it would appear in a
|
|
<B>readline</B>
|
|
|
|
initialization file such as
|
|
<I>.inputrc</I>,
|
|
|
|
but each binding or command must be passed as a separate argument;
|
|
e.g., '"\C-x\C-r": re-read-init-file'.
|
|
Options, if supplied, have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-m </B><I>keymap</I>
|
|
|
|
<DD>
|
|
Use
|
|
<I>keymap</I>
|
|
|
|
as the keymap to be affected by the subsequent bindings.
|
|
Acceptable
|
|
<I>keymap</I>
|
|
|
|
names are
|
|
<I>emacs, emacs-standard, emacs-meta, emacs-ctlx, vi,
|
|
vi-move, vi-command</I>, and
|
|
<I>vi-insert</I>.
|
|
|
|
<I>vi</I> is equivalent to <I>vi-command</I> (<I>vi-move</I> is also
|
|
a synonym); <I>emacs</I> is
|
|
equivalent to <I>emacs-standard</I>.
|
|
<DT><B>-l</B>
|
|
|
|
<DD>
|
|
List the names of all <B>readline</B> functions.
|
|
<DT><B>-p</B>
|
|
|
|
<DD>
|
|
Display <B>readline</B> function names and bindings in such a way
|
|
that they can be re-read.
|
|
<DT><B>-P</B>
|
|
|
|
<DD>
|
|
List current <B>readline</B> function names and bindings.
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
Display <B>readline</B> key sequences bound to macros and the strings
|
|
they output in such a way that they can be re-read.
|
|
<DT><B>-S</B>
|
|
|
|
<DD>
|
|
Display <B>readline</B> key sequences bound to macros and the strings
|
|
they output.
|
|
<DT><B>-v</B>
|
|
|
|
<DD>
|
|
Display <B>readline</B> variable names and values in such a way that they
|
|
can be re-read.
|
|
<DT><B>-V</B>
|
|
|
|
<DD>
|
|
List current <B>readline</B> variable names and values.
|
|
<DT><B>-f </B><I>filename</I>
|
|
|
|
<DD>
|
|
Read key bindings from <I>filename</I>.
|
|
<DT><B>-q </B><I>function</I>
|
|
|
|
<DD>
|
|
Query about which keys invoke the named <I>function</I>.
|
|
<DT><B>-u </B><I>function</I>
|
|
|
|
<DD>
|
|
Unbind all keys bound to the named <I>function</I>.
|
|
<DT><B>-r </B><I>keyseq</I>
|
|
|
|
<DD>
|
|
Remove any current binding for <I>keyseq</I>.
|
|
<DT><B>-x </B><I>keyseq</I>:<I>shell-command</I>
|
|
|
|
<DD>
|
|
Cause <I>shell-command</I> to be executed whenever <I>keyseq</I> is
|
|
entered.
|
|
When <I>shell-command</I> is executed, the shell sets the
|
|
<FONT SIZE=-1><B>READLINE_LINE</B>
|
|
|
|
</FONT>
|
|
variable to the contents of the <B>readline</B> line buffer and the
|
|
<FONT SIZE=-1><B>READLINE_POINT</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>READLINE_MARK</B>
|
|
|
|
</FONT>
|
|
variables to the current location of the insertion point and the saved
|
|
insertion point (the mark), respectively.
|
|
The shell assigns any numeric argument the user supplied to the
|
|
<FONT SIZE=-1><B>READLINE_ARGUMENT</B>
|
|
|
|
</FONT>
|
|
variable.
|
|
If there was no argument, that variable is not set.
|
|
If the executed command changes the value of any of
|
|
<FONT SIZE=-1><B>READLINE_LINE</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>READLINE_POINT</B>,
|
|
|
|
</FONT>
|
|
or
|
|
<FONT SIZE=-1><B>READLINE_MARK</B>,
|
|
|
|
</FONT>
|
|
those new values will be reflected in the editing state.
|
|
<DT><B>-X</B>
|
|
|
|
<DD>
|
|
List all key sequences bound to shell commands and the associated commands
|
|
in a format that can be reused as input.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The return value is 0 unless an unrecognized option is given or an
|
|
error occurred.
|
|
</DL>
|
|
|
|
<DT><B>break</B> [<I>n</I>]<DD>
|
|
Exit from within a
|
|
<B>for</B>,
|
|
|
|
<B>while</B>,
|
|
|
|
<B>until</B>,
|
|
|
|
or
|
|
<B>select</B>
|
|
|
|
loop. If <I>n</I> is specified, break <I>n</I> levels.
|
|
<I>n</I>
|
|
|
|
must be >= 1. If
|
|
<I>n</I>
|
|
|
|
is greater than the number of enclosing loops, all enclosing loops
|
|
are exited.
|
|
The return value is 0 unless <I>n</I> is not greater than or equal to 1.
|
|
<DT><B>builtin</B> <I>shell-builtin</I> [<I>arguments</I>]<DD>
|
|
Execute the specified shell builtin, passing it
|
|
<I>arguments</I>,
|
|
|
|
and return its exit status.
|
|
This is useful when defining a
|
|
function whose name is the same as a shell builtin,
|
|
retaining the functionality of the builtin within the function.
|
|
The <B>cd</B> builtin is commonly redefined this way.
|
|
The return status is false if
|
|
<I>shell-builtin</I>
|
|
|
|
is not a shell builtin command.
|
|
<DT><B>caller</B> [<I>expr</I>]<DD>
|
|
Returns the context of any active subroutine call (a shell function or
|
|
a script executed with the <B>.</B> or <B>source</B> builtins).
|
|
Without <I>expr</I>, <B>caller</B> displays the line number and source
|
|
filename of the current subroutine call.
|
|
If a non-negative integer is supplied as <I>expr</I>, <B>caller</B>
|
|
displays the line number, subroutine name, and source file corresponding
|
|
to that position in the current execution call stack. This extra
|
|
information may be used, for example, to print a stack trace. The
|
|
current frame is frame 0.
|
|
The return value is 0 unless the shell is not executing a subroutine
|
|
call or <I>expr</I> does not correspond to a valid position in the
|
|
call stack.
|
|
<DT><B>cd</B> [<B>-L</B>|[<B>-P</B> [<B>-e</B>]] [-@]] [<I>dir</I>]<DD>
|
|
Change the current directory to <I>dir</I>.
|
|
if <I>dir</I> is not supplied, the value of the
|
|
<FONT SIZE=-1><B>HOME</B>
|
|
|
|
</FONT>
|
|
shell variable is the default.
|
|
The variable
|
|
<FONT SIZE=-1><B>CDPATH</B>
|
|
|
|
</FONT>
|
|
defines the search path for the directory containing
|
|
<I>dir</I>:
|
|
|
|
each directory name in
|
|
<FONT SIZE=-1><B>CDPATH</B>
|
|
|
|
</FONT>
|
|
is searched for <I>dir</I>.
|
|
Alternative directory names in
|
|
<FONT SIZE=-1><B>CDPATH</B>
|
|
|
|
</FONT>
|
|
are separated by a colon (:). A null directory name in
|
|
<FONT SIZE=-1><B>CDPATH</B>
|
|
|
|
</FONT>
|
|
is the same as the current directory, i.e., ``<B>.</B>''. If
|
|
<I>dir</I>
|
|
|
|
begins with a slash (/),
|
|
then
|
|
<FONT SIZE=-1><B>CDPATH</B>
|
|
|
|
</FONT>
|
|
is not used. The
|
|
<B>-P</B>
|
|
|
|
option causes <B>cd</B> to use the physical directory structure
|
|
by resolving symbolic links while traversing <I>dir</I> and
|
|
before processing instances of <I>..</I> in <I>dir</I> (see also the
|
|
<B>-P</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin command); the
|
|
<B>-L</B>
|
|
|
|
option forces symbolic links to be followed by resolving the link
|
|
after processing instances of <I>..</I> in <I>dir</I>.
|
|
If <I>..</I> appears in <I>dir</I>, it is processed by removing the
|
|
immediately previous pathname component from <I>dir</I>, back to a slash
|
|
or the beginning of <I>dir</I>.
|
|
If the
|
|
<B>-e</B>
|
|
|
|
option is supplied with
|
|
<B>-P</B>,
|
|
|
|
and the current working directory cannot be successfully determined
|
|
after a successful directory change, <B>cd</B> will return an unsuccessful
|
|
status.
|
|
On systems that support it, the <B>-@</B> option presents the extended
|
|
attributes associated with a file as a directory.
|
|
An argument of
|
|
<B>-</B>
|
|
|
|
is converted to
|
|
<FONT SIZE=-1><B>$OLDPWD</B>
|
|
|
|
</FONT>
|
|
before the directory change is attempted.
|
|
If a non-empty directory name from
|
|
<FONT SIZE=-1><B>CDPATH</B>
|
|
|
|
</FONT>
|
|
is used, or if
|
|
<B>-</B> is the first argument, and the directory change is
|
|
successful, the absolute pathname of the new working directory is
|
|
written to the standard output.
|
|
If the directory change is successful, <B>cd</B> sets the value of the
|
|
<B>PWD</B> environment variable to the new directory name, and sets the
|
|
<B>OLDPWD</B> environment variable to the value of the current working
|
|
directory before the change.
|
|
The return value is true if the directory was successfully changed;
|
|
false otherwise.
|
|
<DT><B>command</B> [<B>-pVv</B>] <I>command</I> [<I>arg</I> ...]<DD>
|
|
Run
|
|
<I>command</I>
|
|
|
|
with
|
|
<I>args</I>
|
|
|
|
suppressing the normal shell function lookup.
|
|
Only builtin commands or commands found in the
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
are executed. If the
|
|
<B>-p</B>
|
|
|
|
option is given, the search for
|
|
<I>command</I>
|
|
|
|
is performed using a default value for
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
that is guaranteed to find all of the standard utilities.
|
|
If either the
|
|
<B>-V</B>
|
|
|
|
or
|
|
<B>-v</B>
|
|
|
|
option is supplied, a description of
|
|
<I>command</I>
|
|
|
|
is printed. The
|
|
<B>-v</B>
|
|
|
|
option causes a single word indicating the command or filename
|
|
used to invoke
|
|
<I>command</I>
|
|
|
|
to be displayed; the
|
|
<B>-V</B>
|
|
|
|
option produces a more verbose description.
|
|
If the
|
|
<B>-V</B>
|
|
|
|
or
|
|
<B>-v</B>
|
|
|
|
option is supplied, the exit status is 0 if
|
|
<I>command</I>
|
|
|
|
was found, and 1 if not. If neither option is supplied and
|
|
an error occurred or
|
|
<I>command</I>
|
|
|
|
cannot be found, the exit status is 127. Otherwise, the exit status of the
|
|
<B>command</B>
|
|
|
|
builtin is the exit status of
|
|
<I>command</I>.
|
|
|
|
<DT><B>compgen</B> [<I>option</I>] [<I>word</I>]<DD>
|
|
Generate possible completion matches for <I>word</I> according to
|
|
the <I>option</I>s, which may be any option accepted by the
|
|
<B>complete</B>
|
|
|
|
builtin with the exception of <B>-p</B> and <B>-r</B>, and write
|
|
the matches to the standard output.
|
|
When using the <B>-F</B> or <B>-C</B> options, the various shell variables
|
|
set by the programmable completion facilities, while available, will not
|
|
have useful values.
|
|
<P>
|
|
The matches will be generated in the same way as if the programmable
|
|
completion code had generated them directly from a completion specification
|
|
with the same flags.
|
|
If <I>word</I> is specified, only those completions matching <I>word</I>
|
|
will be displayed.
|
|
<P>
|
|
The return value is true unless an invalid option is supplied, or no
|
|
matches were generated.
|
|
<DT><B>complete</B> [<B>-abcdefgjksuv</B>] [<B>-o</B> <I>comp-option</I>] [<B>-DEI</B>] [<B>-A</B> <I>action</I>] [<B>-G</B> <I>globpat</I>] [<B>-W</B> <I>wordlist</I>]<DD>
|
|
<BR>
|
|
|
|
[<B>-F</B> <I>function</I>] [<B>-C</B> <I>command</I>] [<B>-X</B> <I>filterpat</I>] [<B>-P</B> <I>prefix</I>] [<B>-S</B> <I>suffix</I>] <I>name</I> [<I>name ...</I>]
|
|
|
|
<DT><B>complete</B> <B>-pr</B> [<B>-DEI</B>] [<I>name</I> ...]<DD>
|
|
|
|
Specify how arguments to each <I>name</I> should be completed.
|
|
If the <B>-p</B> option is supplied, or if no options are supplied,
|
|
existing completion specifications are printed in a way that allows
|
|
them to be reused as input.
|
|
The <B>-r</B> option removes a completion specification for
|
|
each <I>name</I>, or, if no <I>name</I>s are supplied, all
|
|
completion specifications.
|
|
The <B>-D</B> option indicates that other supplied options and actions should
|
|
apply to the ``default'' command completion; that is, completion attempted
|
|
on a command for which no completion has previously been defined.
|
|
The <B>-E</B> option indicates that other supplied options and actions should
|
|
apply to ``empty'' command completion; that is, completion attempted on a
|
|
blank line.
|
|
The <B>-I</B> option indicates that other supplied options and actions should
|
|
apply to completion on the initial non-assignment word on the line, or after
|
|
a command delimiter such as <B>;</B> or <B>|</B>, which is usually command
|
|
name completion.
|
|
If multiple options are supplied, the <B>-D</B> option takes precedence
|
|
over <B>-E</B>, and both take precedence over <B>-I</B>.
|
|
If any of <B>-D</B>, <B>-E</B>, or <B>-I</B> are supplied, any other
|
|
<I>name</I> arguments are ignored; these completions only apply to the case
|
|
specified by the option.
|
|
<P>
|
|
The process of applying these completion specifications when word completion
|
|
is attempted is described
|
|
|
|
above under <B>Programmable Completion</B>.
|
|
<P>
|
|
Other options, if specified, have the following meanings.
|
|
The arguments to the <B>-G</B>, <B>-W</B>, and <B>-X</B> options
|
|
(and, if necessary, the <B>-P</B> and <B>-S</B> options)
|
|
should be quoted to protect them from expansion before the
|
|
<B>complete</B>
|
|
|
|
builtin is invoked.
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-o</B> <I>comp-option</I><DD>
|
|
The <I>comp-option</I> controls several aspects of the compspec's behavior
|
|
beyond the simple generation of completions.
|
|
<I>comp-option</I> may be one of:
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>bashdefault</B>
|
|
|
|
<DD>
|
|
Perform the rest of the default <B>bash</B> completions if the compspec
|
|
generates no matches.
|
|
<DT><B>default</B>
|
|
|
|
<DD>
|
|
Use readline's default filename completion if the compspec generates
|
|
no matches.
|
|
<DT><B>dirnames</B>
|
|
|
|
<DD>
|
|
Perform directory name completion if the compspec generates no matches.
|
|
<DT><B>filenames</B>
|
|
|
|
<DD>
|
|
Tell readline that the compspec generates filenames, so it can perform any
|
|
filename-specific processing (like adding a slash to directory names,
|
|
quoting special characters, or suppressing trailing spaces).
|
|
Intended to be used with shell functions.
|
|
<DT><B>noquote</B>
|
|
|
|
<DD>
|
|
Tell readline not to quote the completed words if they are filenames
|
|
(quoting filenames is the default).
|
|
<DT><B>nosort</B>
|
|
|
|
<DD>
|
|
Tell readline not to sort the list of possible completions alphabetically.
|
|
<DT><B>nospace</B>
|
|
|
|
<DD>
|
|
Tell readline not to append a space (the default) to words completed at
|
|
the end of the line.
|
|
<DT><B>plusdirs</B>
|
|
|
|
<DD>
|
|
After any matches defined by the compspec are generated,
|
|
directory name completion is attempted and any
|
|
matches are added to the results of the other actions.
|
|
</DL></DL>
|
|
|
|
<DT><B>-A</B> <I>action</I><DD>
|
|
The <I>action</I> may be one of the following to generate a list of possible
|
|
completions:
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>alias</B>
|
|
|
|
<DD>
|
|
Alias names. May also be specified as <B>-a</B>.
|
|
<DT><B>arrayvar</B>
|
|
|
|
<DD>
|
|
Array variable names.
|
|
<DT><B>binding</B>
|
|
|
|
<DD>
|
|
<B>Readline</B> key binding names.
|
|
<DT><B>builtin</B>
|
|
|
|
<DD>
|
|
Names of shell builtin commands. May also be specified as <B>-b</B>.
|
|
<DT><B>command</B>
|
|
|
|
<DD>
|
|
Command names. May also be specified as <B>-c</B>.
|
|
<DT><B>directory</B>
|
|
|
|
<DD>
|
|
Directory names. May also be specified as <B>-d</B>.
|
|
<DT><B>disabled</B>
|
|
|
|
<DD>
|
|
Names of disabled shell builtins.
|
|
<DT><B>enabled</B>
|
|
|
|
<DD>
|
|
Names of enabled shell builtins.
|
|
<DT><B>export</B>
|
|
|
|
<DD>
|
|
Names of exported shell variables. May also be specified as <B>-e</B>.
|
|
<DT><B>file</B>
|
|
|
|
<DD>
|
|
File names. May also be specified as <B>-f</B>.
|
|
<DT><B>function</B>
|
|
|
|
<DD>
|
|
Names of shell functions.
|
|
<DT><B>group</B>
|
|
|
|
<DD>
|
|
Group names. May also be specified as <B>-g</B>.
|
|
<DT><B>helptopic</B>
|
|
|
|
<DD>
|
|
Help topics as accepted by the <B>help</B> builtin.
|
|
<DT><B>hostname</B>
|
|
|
|
<DD>
|
|
Hostnames, as taken from the file specified by the
|
|
<FONT SIZE=-1><B>HOSTFILE</B>
|
|
|
|
</FONT>
|
|
shell variable.
|
|
<DT><B>job</B>
|
|
|
|
<DD>
|
|
Job names, if job control is active. May also be specified as <B>-j</B>.
|
|
<DT><B>keyword</B>
|
|
|
|
<DD>
|
|
Shell reserved words. May also be specified as <B>-k</B>.
|
|
<DT><B>running</B>
|
|
|
|
<DD>
|
|
Names of running jobs, if job control is active.
|
|
<DT><B>service</B>
|
|
|
|
<DD>
|
|
Service names. May also be specified as <B>-s</B>.
|
|
<DT><B>setopt</B>
|
|
|
|
<DD>
|
|
Valid arguments for the <B>-o</B> option to the <B>set</B> builtin.
|
|
<DT><B>shopt</B>
|
|
|
|
<DD>
|
|
Shell option names as accepted by the <B>shopt</B> builtin.
|
|
<DT><B>signal</B>
|
|
|
|
<DD>
|
|
Signal names.
|
|
<DT><B>stopped</B>
|
|
|
|
<DD>
|
|
Names of stopped jobs, if job control is active.
|
|
<DT><B>user</B>
|
|
|
|
<DD>
|
|
User names. May also be specified as <B>-u</B>.
|
|
<DT><B>variable</B>
|
|
|
|
<DD>
|
|
Names of all shell variables. May also be specified as <B>-v</B>.
|
|
</DL></DL>
|
|
|
|
<DT><B>-C</B> <I>command</I><DD>
|
|
<I>command</I> is executed in a subshell environment, and its output is
|
|
used as the possible completions.
|
|
Arguments are passed as with the <B>-F</B> option.
|
|
<DT><B>-F</B> <I>function</I><DD>
|
|
The shell function <I>function</I> is executed in the current shell
|
|
environment.
|
|
When the function is executed,
|
|
the first argument (<B>$1</B>) is the name of the command whose arguments are
|
|
being completed,
|
|
the second argument (<B>$2</B>) is the word being completed,
|
|
and the third argument (<B>$3</B>) is the word preceding the word being
|
|
completed on the current command line.
|
|
When it finishes, the possible completions are retrieved from the value
|
|
of the
|
|
<FONT SIZE=-1><B>COMPREPLY</B>
|
|
|
|
</FONT>
|
|
array variable.
|
|
<DT><B>-G</B> <I>globpat</I><DD>
|
|
The pathname expansion pattern <I>globpat</I> is expanded to generate
|
|
the possible completions.
|
|
<DT><B>-P</B> <I>prefix</I><DD>
|
|
<I>prefix</I> is added at the beginning of each possible completion
|
|
after all other options have been applied.
|
|
<DT><B>-S</B> <I>suffix</I><DD>
|
|
<I>suffix</I> is appended to each possible completion
|
|
after all other options have been applied.
|
|
<DT><B>-W</B> <I>wordlist</I><DD>
|
|
The <I>wordlist</I> is split using the characters in the
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
special variable as delimiters, and each resultant word is expanded.
|
|
Shell quoting is honored within <I>wordlist</I>,
|
|
in order to provide a
|
|
mechanism for the words to contain shell metacharacters or characters
|
|
in the value of
|
|
<FONT SIZE=-1><B>IFS</B>.
|
|
|
|
</FONT>
|
|
The possible completions are the members of the resultant list which
|
|
match the word being completed.
|
|
<DT><B>-X</B> <I>filterpat</I><DD>
|
|
<I>filterpat</I> is a pattern as used for pathname expansion.
|
|
It is applied to the list of possible completions generated by the
|
|
preceding options and arguments, and each completion matching
|
|
<I>filterpat</I> is removed from the list.
|
|
A leading <B>!</B> in <I>filterpat</I> negates the pattern; in this
|
|
case, any completion not matching <I>filterpat</I> is removed.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The return value is true unless an invalid option is supplied, an option
|
|
other than <B>-p</B> or <B>-r</B> is supplied without a <I>name</I>
|
|
argument, an attempt is made to remove a completion specification for
|
|
a <I>name</I> for which no specification exists, or
|
|
an error occurs adding a completion specification.
|
|
</DL>
|
|
|
|
<DT><B>compopt</B> [<B>-o</B> <I>option</I>] [<B>-DEI</B>] [<B>+o</B> <I>option</I>] [<I>name</I>]<DD>
|
|
Modify completion options for each <I>name</I> according to the
|
|
<I>option</I>s, or for the
|
|
currently-executing completion if no <I>name</I>s are supplied.
|
|
If no <I>option</I>s are given, display the completion options for each
|
|
<I>name</I> or the current completion.
|
|
The possible values of <I>option</I> are those valid for the <B>complete</B>
|
|
builtin described above.
|
|
The <B>-D</B> option indicates that other supplied options should
|
|
apply to the ``default'' command completion; that is, completion attempted
|
|
on a command for which no completion has previously been defined.
|
|
The <B>-E</B> option indicates that other supplied options should
|
|
apply to ``empty'' command completion; that is, completion attempted on a
|
|
blank line.
|
|
The <B>-I</B> option indicates that other supplied options should
|
|
apply to completion on the initial non-assignment word on the line,
|
|
or after a command delimiter such as <B>;</B> or <B>|</B>, which is usually
|
|
command name completion.
|
|
<P>
|
|
The return value is true unless an invalid option is supplied, an attempt
|
|
is made to modify the options for a <I>name</I> for which no completion
|
|
specification exists, or an output error occurs.
|
|
<DT><B>continue</B> [<I>n</I>]<DD>
|
|
Resume the next iteration of the enclosing
|
|
<B>for</B>,
|
|
|
|
<B>while</B>,
|
|
|
|
<B>until</B>,
|
|
|
|
or
|
|
<B>select</B>
|
|
|
|
loop.
|
|
If
|
|
<I>n</I>
|
|
|
|
is specified, resume at the <I>n</I>th enclosing loop.
|
|
<I>n</I>
|
|
|
|
must be >= 1. If
|
|
<I>n</I>
|
|
|
|
is greater than the number of enclosing loops, the last enclosing loop
|
|
(the ``top-level'' loop) is resumed.
|
|
The return value is 0 unless <I>n</I> is not greater than or equal to 1.
|
|
<DT><B>declare</B> [<B>-aAfFgiIlnrtux</B>] [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD>
|
|
|
|
<DT><B>typeset</B> [<B>-aAfFgiIlnrtux</B>] [<B>-p</B>] [<I>name</I>[=<I>value</I>] ...]<DD>
|
|
|
|
Declare variables and/or give them attributes.
|
|
If no <I>name</I>s are given then display the values of variables.
|
|
The
|
|
<B>-p</B>
|
|
|
|
option will display the attributes and values of each
|
|
<I>name</I>.
|
|
|
|
When
|
|
<B>-p</B>
|
|
|
|
is used with <I>name</I> arguments, additional options,
|
|
other than <B>-f</B> and <B>-F</B>, are ignored.
|
|
When
|
|
<B>-p</B>
|
|
|
|
is supplied without <I>name</I> arguments, it will display the attributes
|
|
and values of all variables having the attributes specified by the
|
|
additional options.
|
|
If no other options are supplied with <B>-p</B>, <B>declare</B> will display
|
|
the attributes and values of all shell variables. The <B>-f</B> option
|
|
will restrict the display to shell functions.
|
|
The
|
|
<B>-F</B>
|
|
|
|
option inhibits the display of function definitions; only the
|
|
function name and attributes are printed.
|
|
If the <B>extdebug</B> shell option is enabled using <B>shopt</B>,
|
|
the source file name and line number where each <I>name</I>
|
|
is defined are displayed as well. The
|
|
<B>-F</B>
|
|
|
|
option implies
|
|
<B>-f</B>.
|
|
|
|
The
|
|
<B>-g</B>
|
|
|
|
option forces variables to be created or modified at the global scope,
|
|
even when <B>declare</B> is executed in a shell function.
|
|
It is ignored in all other cases.
|
|
The
|
|
<B>-I</B>
|
|
|
|
option causes local variables to inherit the attributes
|
|
(except the <I>nameref</I> attribute)
|
|
and value of any existing variable with the same
|
|
<I>name</I> at a surrounding scope.
|
|
If there is no existing variable, the local variable is initially unset.
|
|
The following options can
|
|
be used to restrict output to variables with the specified attribute or
|
|
to give variables attributes:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-a</B>
|
|
|
|
<DD>
|
|
Each <I>name</I> is an indexed array variable (see
|
|
<B>Arrays</B>
|
|
|
|
|
|
above).
|
|
<DT><B>-A</B>
|
|
|
|
<DD>
|
|
Each <I>name</I> is an associative array variable (see
|
|
<B>Arrays</B>
|
|
|
|
|
|
above).
|
|
<DT><B>-f</B>
|
|
|
|
<DD>
|
|
Use function names only.
|
|
<DT><B>-i</B>
|
|
|
|
<DD>
|
|
The variable is treated as an integer; arithmetic evaluation (see
|
|
<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>
|
|
|
|
</FONT>
|
|
|
|
above)
|
|
is performed when the variable is assigned a value.
|
|
<DT><B>-l</B>
|
|
|
|
<DD>
|
|
When the variable is assigned a value, all upper-case characters are
|
|
converted to lower-case.
|
|
The upper-case attribute is disabled.
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
Give each <I>name</I> the <I>nameref</I> attribute, making
|
|
it a name reference to another variable.
|
|
That other variable is defined by the value of <I>name</I>.
|
|
All references, assignments, and attribute modifications
|
|
to <I>name</I>, except those using or changing the
|
|
<B>-n</B> attribute itself, are performed on the variable referenced by
|
|
<I>name</I>'s value.
|
|
The nameref attribute cannot be applied to array variables.
|
|
<DT><B>-r</B>
|
|
|
|
<DD>
|
|
Make <I>name</I>s readonly. These names cannot then be assigned values
|
|
by subsequent assignment statements or unset.
|
|
<DT><B>-t</B>
|
|
|
|
<DD>
|
|
Give each <I>name</I> the <I>trace</I> attribute.
|
|
Traced functions inherit the <B>DEBUG</B> and <B>RETURN</B> traps from
|
|
the calling shell.
|
|
The trace attribute has no special meaning for variables.
|
|
<DT><B>-u</B>
|
|
|
|
<DD>
|
|
When the variable is assigned a value, all lower-case characters are
|
|
converted to upper-case.
|
|
The lower-case attribute is disabled.
|
|
<DT><B>-x</B>
|
|
|
|
<DD>
|
|
Mark <I>name</I>s for export to subsequent commands via the environment.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
Using `+' instead of `-'
|
|
turns off the attribute instead,
|
|
with the exceptions that <B>+a</B> and <B>+A</B>
|
|
may not be used to destroy array variables and <B>+r</B> will not
|
|
remove the readonly attribute.
|
|
When used in a function,
|
|
<B>declare</B>
|
|
|
|
and
|
|
<B>typeset</B>
|
|
|
|
make each
|
|
<I>name</I> local, as with the
|
|
<B>local</B>
|
|
|
|
command,
|
|
unless the <B>-g</B> option is supplied.
|
|
If a variable name is followed by =<I>value</I>, the value of
|
|
the variable is set to <I>value</I>.
|
|
When using <B>-a</B> or <B>-A</B> and the compound assignment syntax to
|
|
create array variables, additional attributes do not take effect until
|
|
subsequent assignments.
|
|
The return value is 0 unless an invalid option is encountered,
|
|
an attempt is made to define a function using
|
|
|
|
<TT>-f foo=bar</TT>,
|
|
an attempt is made to assign a value to a readonly variable,
|
|
an attempt is made to assign a value to an array variable without
|
|
using the compound assignment syntax (see
|
|
<B>Arrays</B>
|
|
|
|
|
|
above),
|
|
one of the <I>names</I> is not a valid shell variable name,
|
|
an attempt is made to turn off readonly status for a readonly variable,
|
|
an attempt is made to turn off array status for an array variable,
|
|
or an attempt is made to display a non-existent function with <B>-f</B>.
|
|
</DL>
|
|
|
|
<DT><B>dirs [-clpv</B>] [+<I>n</I>] [-<I>n</I>]
|
|
|
|
<DD>
|
|
Without options, displays the list of currently remembered directories.
|
|
The default display is on a single line with directory names separated
|
|
by spaces.
|
|
Directories are added to the list with the
|
|
<B>pushd</B>
|
|
|
|
command; the
|
|
<B>popd</B>
|
|
|
|
command removes entries from the list.
|
|
The current directory is always the first directory in the stack.
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-c</B>
|
|
|
|
<DD>
|
|
Clears the directory stack by deleting all of the entries.
|
|
<DT><B>-l</B>
|
|
|
|
<DD>
|
|
Produces a listing using full pathnames;
|
|
the default listing format uses a tilde to denote the home directory.
|
|
<DT><B>-p</B>
|
|
|
|
<DD>
|
|
Print the directory stack with one entry per line.
|
|
<DT><B>-v</B>
|
|
|
|
<DD>
|
|
Print the directory stack with one entry per line,
|
|
prefixing each entry with its index in the stack.
|
|
<DT><B>+</B><I>n</I><DD>
|
|
Displays the <I>n</I>th entry counting from the left of the list
|
|
shown by
|
|
<B>dirs</B>
|
|
|
|
when invoked without options, starting with zero.
|
|
<DT><B>-</B><I>n</I><DD>
|
|
Displays the <I>n</I>th entry counting from the right of the list
|
|
shown by
|
|
<B>dirs</B>
|
|
|
|
when invoked without options, starting with zero.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The return value is 0 unless an
|
|
invalid option is supplied or <I>n</I> indexes beyond the end
|
|
of the directory stack.
|
|
</DL>
|
|
|
|
<DT><B>disown</B> [<B>-ar</B>] [<B>-h</B>] [<I>jobspec</I> ... | <I>pid</I> ... ]<DD>
|
|
Without options, remove each
|
|
<I>jobspec</I>
|
|
|
|
from the table of active jobs.
|
|
If
|
|
<I>jobspec</I>
|
|
|
|
is not present, and neither the <B>-a</B> nor the <B>-r</B> option
|
|
is supplied, the <I>current job</I> is used.
|
|
If the <B>-h</B> option is given, each
|
|
<I>jobspec</I>
|
|
|
|
is not removed from the table, but is marked so that
|
|
<FONT SIZE=-1><B>SIGHUP</B>
|
|
|
|
</FONT>
|
|
is not sent to the job if the shell receives a
|
|
<FONT SIZE=-1><B>SIGHUP</B>.
|
|
|
|
</FONT>
|
|
If no
|
|
<I>jobspec</I>
|
|
|
|
is supplied, the
|
|
<B>-a</B>
|
|
|
|
option means to remove or mark all jobs; the
|
|
<B>-r</B>
|
|
|
|
option without a
|
|
<I>jobspec</I>
|
|
|
|
argument restricts operation to running jobs.
|
|
The return value is 0 unless a
|
|
<I>jobspec</I>
|
|
|
|
does not specify a valid job.
|
|
<DT><B>echo</B> [<B>-neE</B>] [<I>arg</I> ...]<DD>
|
|
Output the <I>arg</I>s, separated by spaces, followed by a newline.
|
|
The return status is 0 unless a write error occurs.
|
|
If <B>-n</B> is specified, the trailing newline is
|
|
suppressed. If the <B>-e</B> option is given, interpretation of
|
|
the following backslash-escaped characters is enabled. The
|
|
<B>-E</B>
|
|
|
|
option disables the interpretation of these escape characters,
|
|
even on systems where they are interpreted by default.
|
|
The <B>xpg_echo</B> shell option may be used to
|
|
dynamically determine whether or not <B>echo</B> expands these
|
|
escape characters by default.
|
|
<B>echo</B>
|
|
|
|
does not interpret <B>--</B> to mean the end of options.
|
|
<B>echo</B>
|
|
|
|
interprets the following escape sequences:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>\a</B>
|
|
|
|
<DD>
|
|
alert (bell)
|
|
<DT><B>\b</B>
|
|
|
|
<DD>
|
|
backspace
|
|
<DT><B>\c</B>
|
|
|
|
<DD>
|
|
suppress further output
|
|
<DT><B>\e</B>
|
|
|
|
<DD>
|
|
<DT><B>\E</B>
|
|
|
|
<DD>
|
|
an escape character
|
|
<DT><B>\f</B>
|
|
|
|
<DD>
|
|
form feed
|
|
<DT><B>\n</B>
|
|
|
|
<DD>
|
|
new line
|
|
<DT><B>\r</B>
|
|
|
|
<DD>
|
|
carriage return
|
|
<DT><B>\t</B>
|
|
|
|
<DD>
|
|
horizontal tab
|
|
<DT><B>\v</B>
|
|
|
|
<DD>
|
|
vertical tab
|
|
<DT><B>\\</B>
|
|
|
|
<DD>
|
|
backslash
|
|
<DT><B>\0</B><I>nnn</I>
|
|
|
|
<DD>
|
|
the eight-bit character whose value is the octal value <I>nnn</I>
|
|
(zero to three octal digits)
|
|
<DT><B>\x</B><I>HH</I>
|
|
|
|
<DD>
|
|
the eight-bit character whose value is the hexadecimal value <I>HH</I>
|
|
(one or two hex digits)
|
|
<DT><B>\u</B><I>HHHH</I>
|
|
|
|
<DD>
|
|
the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
|
|
<I>HHHH</I> (one to four hex digits)
|
|
<DT><B>\U</B><I>HHHHHHHH</I>
|
|
|
|
<DD>
|
|
the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value
|
|
<I>HHHHHHHH</I> (one to eight hex digits)
|
|
|
|
</DL></DL>
|
|
|
|
<DT><B>enable</B> [<B>-a</B>] [<B>-dnps</B>] [<B>-f</B> <I>filename</I>] [<I>name</I> ...]<DD>
|
|
Enable and disable builtin shell commands.
|
|
Disabling a builtin allows a disk command which has the same name
|
|
as a shell builtin to be executed without specifying a full pathname,
|
|
even though the shell normally searches for builtins before disk commands.
|
|
If <B>-n</B> is used, each <I>name</I>
|
|
is disabled; otherwise,
|
|
<I>names</I> are enabled. For example, to use the
|
|
<B>test</B>
|
|
|
|
binary found via the
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
instead of the shell builtin version, run
|
|
<TT>enable -n test</TT>.
|
|
|
|
The
|
|
<B>-f</B>
|
|
|
|
option means to load the new builtin command
|
|
<I>name</I>
|
|
|
|
from shared object
|
|
<I>filename</I>,
|
|
|
|
on systems that support dynamic loading.
|
|
Bash will use the value of the <B>BASH_LOADABLES_PATH</B> variable as a
|
|
colon-separated list of directories in which to search for <I>filename</I>.
|
|
The default is system-dependent.
|
|
The
|
|
<B>-d</B>
|
|
|
|
option will delete a builtin previously loaded with
|
|
<B>-f</B>.
|
|
|
|
If no <I>name</I> arguments are given, or if the
|
|
<B>-p</B>
|
|
|
|
option is supplied, a list of shell builtins is printed.
|
|
With no other option arguments, the list consists of all enabled
|
|
shell builtins.
|
|
If <B>-n</B> is supplied, only disabled builtins are printed.
|
|
If <B>-a</B> is supplied, the list printed includes all builtins, with an
|
|
indication of whether or not each is enabled.
|
|
If <B>-s</B> is supplied, the output is restricted to the POSIX
|
|
<I>special</I> builtins.
|
|
If no options are supplied and a <I>name</I> is not a shell builtin,
|
|
<B>enable</B> will attempt to load <I>name</I> from a shared object named
|
|
<I>name</I>, as if the command were
|
|
<TT>enable -f</TT> <I>name name</I> .
|
|
|
|
The return value is 0 unless a
|
|
<I>name</I>
|
|
|
|
is not a shell builtin or there is an error loading a new builtin
|
|
from a shared object.
|
|
<DT><B>eval</B> [<I>arg</I> ...]<DD>
|
|
The <I>arg</I>s are read and concatenated together into a single
|
|
command. This command is then read and executed by the shell, and
|
|
its exit status is returned as the value of
|
|
<B>eval</B>.
|
|
|
|
If there are no
|
|
<I>args</I>,
|
|
|
|
or only null arguments,
|
|
<B>eval</B>
|
|
|
|
returns 0.
|
|
<DT><B>exec</B> [<B>-cl</B>] [<B>-a</B> <I>name</I>] [<I>command</I> [<I>arguments</I>]]<DD>
|
|
If
|
|
<I>command</I>
|
|
|
|
is specified, it replaces the shell.
|
|
No new process is created. The
|
|
<I>arguments</I>
|
|
|
|
become the arguments to <I>command</I>.
|
|
If the
|
|
<B>-l</B>
|
|
|
|
option is supplied,
|
|
the shell places a dash at the beginning of the zeroth argument passed to
|
|
<I>command</I>.
|
|
|
|
This is what
|
|
<I>login</I>(1)
|
|
|
|
does. The
|
|
<B>-c</B>
|
|
|
|
option causes
|
|
<I>command</I>
|
|
|
|
to be executed with an empty environment. If
|
|
<B>-a</B>
|
|
|
|
is supplied, the shell passes
|
|
<I>name</I>
|
|
|
|
as the zeroth argument to the executed command.
|
|
If
|
|
<I>command</I>
|
|
|
|
cannot be executed for some reason, a non-interactive shell exits,
|
|
unless the
|
|
<B>execfail</B>
|
|
|
|
shell option
|
|
is enabled. In that case, it returns failure.
|
|
An interactive shell returns failure if the file cannot be executed.
|
|
A subshell exits unconditionally if <B>exec</B> fails.
|
|
If
|
|
<I>command</I>
|
|
|
|
is not specified, any redirections take effect in the current shell,
|
|
and the return status is 0. If there is a redirection error, the
|
|
return status is 1.
|
|
<DT><B>exit</B> [<I>n</I>]<DD>
|
|
Cause the shell to exit
|
|
with a status of <I>n</I>. If
|
|
<I>n</I>
|
|
|
|
is omitted, the exit status
|
|
is that of the last command executed.
|
|
A trap on
|
|
<FONT SIZE=-1><B>EXIT</B>
|
|
|
|
</FONT>
|
|
is executed before the shell terminates.
|
|
<DT><B>export</B> [<B>-fn</B>] [<I>name</I>[=<I>word</I>]] ...<DD>
|
|
|
|
<DT><B>export -p</B>
|
|
|
|
<DD>
|
|
|
|
The supplied
|
|
<I>names</I>
|
|
|
|
are marked for automatic export to the environment of
|
|
subsequently executed commands. If the
|
|
<B>-f</B>
|
|
|
|
option is given, the
|
|
<I>names</I>
|
|
|
|
refer to functions.
|
|
If no
|
|
<I>names</I>
|
|
|
|
are given, or if the
|
|
<B>-p</B>
|
|
|
|
option is supplied, a list
|
|
of names of all exported variables is printed.
|
|
The
|
|
<B>-n</B>
|
|
|
|
option causes the export property to be removed from each
|
|
<I>name</I>.
|
|
If a variable name is followed by =<I>word</I>, the value of
|
|
the variable is set to <I>word</I>.
|
|
<B>export</B>
|
|
|
|
returns an exit status of 0 unless an invalid option is
|
|
encountered,
|
|
one of the <I>names</I> is not a valid shell variable name, or
|
|
<B>-f</B>
|
|
|
|
is supplied with a
|
|
<I>name</I>
|
|
|
|
that is not a function.
|
|
<DT><B>fc</B> [<B>-e</B> <I>ename</I>] [<B>-lnr</B>] [<I>first</I>] [<I>last</I>]<DD>
|
|
|
|
<DT><B>fc</B> <B>-s</B> [<I>pat</I>=<I>rep</I>] [<I>cmd</I>]<DD>
|
|
|
|
The first form selects a range of commands from
|
|
<I>first</I>
|
|
|
|
to
|
|
<I>last</I>
|
|
|
|
from the history list and displays or edits and re-executes them.
|
|
<I>First</I>
|
|
|
|
and
|
|
<I>last</I>
|
|
|
|
may be specified as a string (to locate the last command beginning
|
|
with that string) or as a number (an index into the history list,
|
|
where a negative number is used as an offset from the current
|
|
command number).
|
|
When listing, a <I>first</I> or <I>last</I> of
|
|
0 is equivalent to -1 and -0 is equivalent to the current
|
|
command (usually the <B>fc</B> command); otherwise 0 is equivalent to -1
|
|
and -0 is invalid.
|
|
If
|
|
<I>last</I>
|
|
|
|
is not specified, it is set to
|
|
the current command for listing (so that
|
|
|
|
<TT>fc -l -10</TT>
|
|
prints the last 10 commands) and to
|
|
<I>first</I>
|
|
|
|
otherwise.
|
|
If
|
|
<I>first</I>
|
|
|
|
is not specified, it is set to the previous
|
|
command for editing and -16 for listing.
|
|
<P>
|
|
The
|
|
<B>-n</B>
|
|
|
|
option suppresses
|
|
the command numbers when listing. The
|
|
<B>-r</B>
|
|
|
|
option reverses the order of
|
|
the commands. If the
|
|
<B>-l</B>
|
|
|
|
option is given,
|
|
the commands are listed on
|
|
standard output. Otherwise, the editor given by
|
|
<I>ename</I>
|
|
|
|
is invoked
|
|
on a file containing those commands. If
|
|
<I>ename</I>
|
|
|
|
is not given, the
|
|
value of the
|
|
<FONT SIZE=-1><B>FCEDIT</B>
|
|
|
|
</FONT>
|
|
variable is used, and
|
|
the value of
|
|
<FONT SIZE=-1><B>EDITOR</B>
|
|
|
|
</FONT>
|
|
if
|
|
<FONT SIZE=-1><B>FCEDIT</B>
|
|
|
|
</FONT>
|
|
is not set. If neither variable is set,
|
|
|
|
<I>vi</I>
|
|
|
|
is used. When editing is complete, the edited commands are
|
|
echoed and executed.
|
|
<P>
|
|
In the second form, <I>command</I> is re-executed after each instance
|
|
of <I>pat</I> is replaced by <I>rep</I>.
|
|
<I>Command</I> is interpreted the same as <I>first</I> above.
|
|
A useful alias to use with this is
|
|
|
|
<TT>r='fc -s'</TT>,
|
|
so that typing
|
|
|
|
<TT>r cc</TT>
|
|
runs the last command beginning with
|
|
|
|
<TT>cc</TT>
|
|
and typing
|
|
|
|
<TT>r</TT>
|
|
re-executes the last command.
|
|
<P>
|
|
If the first form is used, the return value is 0 unless an invalid
|
|
option is encountered or
|
|
<I>first</I>
|
|
|
|
or
|
|
<I>last</I>
|
|
|
|
specify history lines out of range.
|
|
If the
|
|
<B>-e</B>
|
|
|
|
option is supplied, the return value is the value of the last
|
|
command executed or failure if an error occurs with the temporary
|
|
file of commands. If the second form is used, the return status
|
|
is that of the command re-executed, unless
|
|
<I>cmd</I>
|
|
|
|
does not specify a valid history line, in which case
|
|
<B>fc</B>
|
|
|
|
returns failure.
|
|
<DT><B>fg</B> [<I>jobspec</I>]<DD>
|
|
Resume
|
|
<I>jobspec</I>
|
|
|
|
in the foreground, and make it the current job.
|
|
If
|
|
<I>jobspec</I>
|
|
|
|
is not present, the shell's notion of the <I>current job</I> is used.
|
|
The return value is that of the command placed into the foreground,
|
|
or failure if run when job control is disabled or, when run with
|
|
job control enabled, if
|
|
<I>jobspec</I>
|
|
|
|
does not specify a valid job or
|
|
<I>jobspec</I>
|
|
|
|
specifies a job that was started without job control.
|
|
<DT><B>getopts</B> <I>optstring</I> <I>name</I> [<I>arg ...</I>]<DD>
|
|
<B>getopts</B>
|
|
|
|
is used by shell procedures to parse positional parameters.
|
|
<I>optstring</I>
|
|
|
|
contains the option characters to be recognized; if a character
|
|
is followed by a colon, the option is expected to have an
|
|
argument, which should be separated from it by white space.
|
|
The colon and question mark characters may not be used as
|
|
option characters.
|
|
Each time it is invoked,
|
|
<B>getopts</B>
|
|
|
|
places the next option in the shell variable
|
|
<I>name</I>,
|
|
|
|
initializing
|
|
<I>name</I>
|
|
|
|
if it does not exist,
|
|
and the index of the next argument to be processed into the
|
|
variable
|
|
<FONT SIZE=-1><B>OPTIND</B>.
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>OPTIND</B>
|
|
|
|
</FONT>
|
|
is initialized to 1 each time the shell or a shell script
|
|
is invoked. When an option requires an argument,
|
|
<B>getopts</B>
|
|
|
|
places that argument into the variable
|
|
<FONT SIZE=-1><B>OPTARG</B>.
|
|
|
|
</FONT>
|
|
The shell does not reset
|
|
<FONT SIZE=-1><B>OPTIND</B>
|
|
|
|
</FONT>
|
|
automatically; it must be manually reset between multiple
|
|
calls to
|
|
<B>getopts</B>
|
|
|
|
within the same shell invocation if a new set of parameters
|
|
is to be used.
|
|
<P>
|
|
When the end of options is encountered, <B>getopts</B> exits with a
|
|
return value greater than zero.
|
|
<FONT SIZE=-1><B>OPTIND</B>
|
|
|
|
</FONT>
|
|
is set to the index of the first non-option argument,
|
|
and <I>name</I> is set to ?.
|
|
<P>
|
|
<B>getopts</B>
|
|
|
|
normally parses the positional parameters, but if more arguments are
|
|
supplied as
|
|
<I>arg</I>
|
|
|
|
values,
|
|
<B>getopts</B>
|
|
|
|
parses those instead.
|
|
<P>
|
|
<B>getopts</B>
|
|
|
|
can report errors in two ways. If the first character of
|
|
<I>optstring</I>
|
|
|
|
is a colon,
|
|
<I>silent</I>
|
|
|
|
error reporting is used. In normal operation, diagnostic messages
|
|
are printed when invalid options or missing option arguments are
|
|
encountered.
|
|
If the variable
|
|
<FONT SIZE=-1><B>OPTERR</B>
|
|
|
|
</FONT>
|
|
is set to 0, no error messages will be displayed, even if the first
|
|
character of
|
|
<I>optstring</I>
|
|
|
|
is not a colon.
|
|
<P>
|
|
If an invalid option is seen,
|
|
<B>getopts</B>
|
|
|
|
places ? into
|
|
<I>name</I>
|
|
|
|
and, if not silent,
|
|
prints an error message and unsets
|
|
<FONT SIZE=-1><B>OPTARG</B>.
|
|
|
|
</FONT>
|
|
If
|
|
<B>getopts</B>
|
|
|
|
is silent,
|
|
the option character found is placed in
|
|
<FONT SIZE=-1><B>OPTARG</B>
|
|
|
|
</FONT>
|
|
and no diagnostic message is printed.
|
|
<P>
|
|
If a required argument is not found, and
|
|
<B>getopts</B>
|
|
|
|
is not silent,
|
|
a question mark (<B>?</B>) is placed in
|
|
<I>name</I>,
|
|
|
|
<FONT SIZE=-1><B>OPTARG</B>
|
|
|
|
</FONT>
|
|
is unset, and a diagnostic message is printed.
|
|
If
|
|
<B>getopts</B>
|
|
|
|
is silent, then a colon (<B>:</B>) is placed in
|
|
<I>name</I>
|
|
|
|
and
|
|
<FONT SIZE=-1><B>OPTARG</B>
|
|
|
|
</FONT>
|
|
is set to the option character found.
|
|
<P>
|
|
<B>getopts</B>
|
|
|
|
returns true if an option, specified or unspecified, is found.
|
|
It returns false if the end of options is encountered or an
|
|
error occurs.
|
|
<DT><B>hash</B> [<B>-lr</B>] [<B>-p</B> <I>filename</I>] [<B>-dt</B>] [<I>name</I>]<DD>
|
|
Each time <B>hash</B> is invoked,
|
|
the full pathname of the command
|
|
<I>name</I>
|
|
|
|
is determined by searching
|
|
the directories in
|
|
<B>$PATH</B>
|
|
|
|
and remembered. Any previously-remembered pathname is discarded.
|
|
If the
|
|
<B>-p</B>
|
|
|
|
option is supplied, no path search is performed, and
|
|
<I>filename</I>
|
|
|
|
is used as the full filename of the command.
|
|
The
|
|
<B>-r</B>
|
|
|
|
option causes the shell to forget all
|
|
remembered locations.
|
|
The
|
|
<B>-d</B>
|
|
|
|
option causes the shell to forget the remembered location of each <I>name</I>.
|
|
If the
|
|
<B>-t</B>
|
|
|
|
option is supplied, the full pathname to which each <I>name</I> corresponds
|
|
is printed. If multiple <I>name</I> arguments are supplied with <B>-t</B>,
|
|
the <I>name</I> is printed before the hashed full pathname.
|
|
The
|
|
<B>-l</B>
|
|
|
|
option causes output to be displayed in a format that may be reused as input.
|
|
If no arguments are given, or if only <B>-l</B> is supplied,
|
|
information about remembered commands is printed.
|
|
The return status is true unless a
|
|
<I>name</I>
|
|
|
|
is not found or an invalid option is supplied.
|
|
<DT><B>help</B> [<B>-dms</B>] [<I>pattern</I>]<DD>
|
|
Display helpful information about builtin commands. If
|
|
<I>pattern</I>
|
|
|
|
is specified,
|
|
<B>help</B>
|
|
|
|
gives detailed help on all commands matching
|
|
<I>pattern</I>;
|
|
|
|
otherwise help for all the builtins and shell control structures
|
|
is printed.
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-d</B>
|
|
|
|
<DD>
|
|
Display a short description of each <I>pattern</I>
|
|
<DT><B>-m</B>
|
|
|
|
<DD>
|
|
Display the description of each <I>pattern</I> in a manpage-like format
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
Display only a short usage synopsis for each <I>pattern</I>
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The return status is 0 unless no command matches
|
|
<I>pattern</I>.
|
|
|
|
</DL>
|
|
|
|
<DT><B>history [</B><I>n</I>]<DD>
|
|
|
|
<DT><B>history</B> <B>-c</B><DD>
|
|
<DT><B>history -d</B> <I>offset</I><DD>
|
|
<DT><B>history -d</B> <I>start</I>-<I>end</I><DD>
|
|
<DT><B>history</B> <B>-anrw</B> [<I>filename</I>]<DD>
|
|
<DT><B>history</B> <B>-p</B> <I>arg</I> [<I>arg ...</I>]<DD>
|
|
<DT><B>history</B> <B>-s</B> <I>arg</I> [<I>arg ...</I>]<DD>
|
|
|
|
With no options, display the command
|
|
history list with line numbers. Lines listed
|
|
with a
|
|
<B>*</B>
|
|
|
|
have been modified. An argument of
|
|
<I>n</I>
|
|
|
|
lists only the last
|
|
<I>n</I>
|
|
|
|
lines.
|
|
If the shell variable
|
|
<FONT SIZE=-1><B>HISTTIMEFORMAT</B>
|
|
|
|
</FONT>
|
|
is set and not null,
|
|
it is used as a format string for <I>strftime</I>(3) to display
|
|
the time stamp associated with each displayed history entry.
|
|
No intervening blank is printed between the formatted time stamp
|
|
and the history line.
|
|
If <I>filename</I> is supplied, it is used as the
|
|
name of the history file; if not, the value of
|
|
<FONT SIZE=-1><B>HISTFILE</B>
|
|
|
|
</FONT>
|
|
is used. Options, if supplied, have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-c</B>
|
|
|
|
<DD>
|
|
Clear the history list by deleting all the entries.
|
|
<DT><B>-d</B> <I>offset</I><DD>
|
|
Delete the history entry at position <I>offset</I>.
|
|
If <I>offset</I> is negative, it is interpreted as relative to one greater
|
|
than the last history position, so negative indices count back from the
|
|
end of the history, and an index of -1 refers to the current
|
|
<B>history -d</B> command.
|
|
<DT><B>-d</B> <I>start</I>-<I>end</I><DD>
|
|
Delete the range of history entries between positions <I>start</I> and
|
|
<I>end</I>, inclusive.
|
|
Positive and negative values for <I>start</I> and <I>end</I>
|
|
are interpreted as described above.
|
|
<DT><B>-a</B>
|
|
|
|
<DD>
|
|
Append the ``new'' history lines to the history file.
|
|
These are history lines entered since the beginning of the current
|
|
<B>bash</B> session, but not already appended to the history file.
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
Read the history lines not already read from the history
|
|
file into the current history list. These are lines
|
|
appended to the history file since the beginning of the
|
|
current <B>bash</B> session.
|
|
<DT><B>-r</B>
|
|
|
|
<DD>
|
|
Read the contents of the history file
|
|
and append them to the current history list.
|
|
<DT><B>-w</B>
|
|
|
|
<DD>
|
|
Write the current history list to the history file, overwriting the
|
|
history file's contents.
|
|
<DT><B>-p</B>
|
|
|
|
<DD>
|
|
Perform history substitution on the following <I>args</I> and display
|
|
the result on the standard output.
|
|
Does not store the results in the history list.
|
|
Each <I>arg</I> must be quoted to disable normal history expansion.
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
Store the
|
|
<I>args</I>
|
|
|
|
in the history list as a single entry. The last command in the
|
|
history list is removed before the
|
|
<I>args</I>
|
|
|
|
are added.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If the
|
|
<FONT SIZE=-1><B>HISTTIMEFORMAT</B>
|
|
|
|
</FONT>
|
|
variable is set, the time stamp information
|
|
associated with each history entry is written to the history file,
|
|
marked with the history comment character.
|
|
When the history file is read, lines beginning with the history
|
|
comment character followed immediately by a digit are interpreted
|
|
as timestamps for the following history entry.
|
|
The return value is 0 unless an invalid option is encountered, an
|
|
error occurs while reading or writing the history file, an invalid
|
|
<I>offset</I> or range is supplied as an argument to <B>-d</B>, or the
|
|
history expansion supplied as an argument to <B>-p</B> fails.
|
|
</DL>
|
|
|
|
<DT><B>jobs</B> [<B>-lnprs</B>] [ <I>jobspec</I> ... ]<DD>
|
|
|
|
<DT><B>jobs</B> <B>-x</B> <I>command</I> [ <I>args</I> ... ]<DD>
|
|
|
|
The first form lists the active jobs. The options have the following
|
|
meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-l</B>
|
|
|
|
<DD>
|
|
List process IDs
|
|
in addition to the normal information.
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
Display information only about jobs that have changed status since
|
|
the user was last notified of their status.
|
|
<DT><B>-p</B>
|
|
|
|
<DD>
|
|
List only the process ID of the job's process group
|
|
leader.
|
|
<DT><B>-r</B>
|
|
|
|
<DD>
|
|
Display only running jobs.
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
Display only stopped jobs.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If
|
|
<I>jobspec</I>
|
|
|
|
is given, output is restricted to information about that job.
|
|
The return status is 0 unless an invalid option is encountered
|
|
or an invalid
|
|
<I>jobspec</I>
|
|
|
|
is supplied.
|
|
<P>
|
|
|
|
If the
|
|
<B>-x</B>
|
|
|
|
option is supplied,
|
|
<B>jobs</B>
|
|
|
|
replaces any
|
|
<I>jobspec</I>
|
|
|
|
found in
|
|
<I>command</I>
|
|
|
|
or
|
|
<I>args</I>
|
|
|
|
with the corresponding process group ID, and executes
|
|
<I>command</I>
|
|
|
|
passing it
|
|
<I>args</I>,
|
|
|
|
returning its exit status.
|
|
</DL>
|
|
|
|
<DT><B>kill</B> [<B>-s</B> <I>sigspec</I> | <B>-n</B> <I>signum</I> | <B>-</B><I>sigspec</I>] [<I>pid</I> | <I>jobspec</I>] ...<DD>
|
|
|
|
<DT><B>kill</B> <B>-l</B>|<B>-L</B> [<I>sigspec</I> | <I>exit_status</I>]<DD>
|
|
|
|
Send the signal named by
|
|
<I>sigspec</I>
|
|
|
|
or
|
|
<I>signum</I>
|
|
|
|
to the processes named by
|
|
<I>pid</I>
|
|
|
|
or
|
|
<I>jobspec</I>.
|
|
|
|
<I>sigspec</I>
|
|
|
|
is either a case-insensitive signal name such as
|
|
<FONT SIZE=-1><B>SIGKILL</B>
|
|
|
|
</FONT>
|
|
(with or without the
|
|
<FONT SIZE=-1><B>SIG</B>
|
|
|
|
</FONT>
|
|
prefix) or a signal number;
|
|
<I>signum</I>
|
|
|
|
is a signal number.
|
|
If
|
|
<I>sigspec</I>
|
|
|
|
is not present, then
|
|
<FONT SIZE=-1><B>SIGTERM</B>
|
|
|
|
</FONT>
|
|
is assumed.
|
|
An argument of
|
|
<B>-l</B>
|
|
|
|
lists the signal names.
|
|
If any arguments are supplied when
|
|
<B>-l</B>
|
|
|
|
is given, the names of the signals corresponding to the arguments are
|
|
listed, and the return status is 0.
|
|
The <I>exit_status</I> argument to
|
|
<B>-l</B>
|
|
|
|
is a number specifying either a signal number or the exit status of
|
|
a process terminated by a signal.
|
|
The
|
|
<B>-L</B>
|
|
|
|
option is equivalent to <B>-l</B>.
|
|
<B>kill</B>
|
|
|
|
returns true if at least one signal was successfully sent, or false
|
|
if an error occurs or an invalid option is encountered.
|
|
<DT><B>let</B> <I>arg</I> [<I>arg</I> ...]<DD>
|
|
Each
|
|
<I>arg</I>
|
|
|
|
is an arithmetic expression to be evaluated (see
|
|
<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B>
|
|
|
|
</FONT>
|
|
|
|
above).
|
|
If the last
|
|
<I>arg</I>
|
|
|
|
evaluates to 0,
|
|
<B>let</B>
|
|
|
|
returns 1; 0 is returned otherwise.
|
|
<DT><B>local</B> [<I>option</I>] [<I>name</I>[=<I>value</I>] ... | - ]<DD>
|
|
For each argument, a local variable named
|
|
<I>name</I>
|
|
|
|
is created, and assigned
|
|
<I>value</I>.
|
|
|
|
The <I>option</I> can be any of the options accepted by <B>declare</B>.
|
|
When
|
|
<B>local</B>
|
|
|
|
is used within a function, it causes the variable
|
|
<I>name</I>
|
|
|
|
to have a visible scope restricted to that function and its children.
|
|
If <I>name</I> is -, the set of shell options is made local to the function
|
|
in which <B>local</B> is invoked: shell options changed using the
|
|
<B>set</B> builtin inside the function are restored to their original values
|
|
when the function returns.
|
|
The restore is effected as if a series of <B>set</B> commands were executed
|
|
to restore the values that were in place before the function.
|
|
With no operands,
|
|
<B>local</B>
|
|
|
|
writes a list of local variables to the standard output. It is
|
|
an error to use
|
|
<B>local</B>
|
|
|
|
when not within a function. The return status is 0 unless
|
|
<B>local</B>
|
|
|
|
is used outside a function, an invalid
|
|
<I>name</I>
|
|
|
|
is supplied, or
|
|
<I>name</I> is a readonly variable.
|
|
<DT><B>logout</B>
|
|
|
|
<DD>
|
|
Exit a login shell.
|
|
<DT><B>mapfile</B> [<B>-d</B> <I>delim</I>] [<B>-n</B> <I>count</I>] [<B>-O</B> <I>origin</I>] [<B>-s</B> <I>count</I>] [<B>-t</B>] [<B>-u</B> <I>fd</I>] [<B>-C</B> <I>callback</I>] [<B>-c</B> <I>quantum</I>] [<I>array</I>]<DD>
|
|
|
|
<DT><B>readarray</B> [<B>-d</B> <I>delim</I>] [<B>-n</B> <I>count</I>] [<B>-O</B> <I>origin</I>] [<B>-s</B> <I>count</I>] [<B>-t</B>] [<B>-u</B> <I>fd</I>] [<B>-C</B> <I>callback</I>] [<B>-c</B> <I>quantum</I>] [<I>array</I>]<DD>
|
|
|
|
Read lines from the standard input into the indexed array variable
|
|
<I>array</I>,
|
|
|
|
or from file descriptor
|
|
<I>fd</I>
|
|
|
|
if the
|
|
<B>-u</B>
|
|
|
|
option is supplied.
|
|
The variable
|
|
<FONT SIZE=-1><B>MAPFILE</B>
|
|
|
|
</FONT>
|
|
is the default <I>array</I>.
|
|
Options, if supplied, have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-d</B>
|
|
|
|
<DD>
|
|
The first character of <I>delim</I> is used to terminate each input line,
|
|
rather than newline.
|
|
If <I>delim</I> is the empty string, <B>mapfile</B> will terminate a line
|
|
when it reads a NUL character.
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
Copy at most
|
|
<I>count</I>
|
|
|
|
lines. If <I>count</I> is 0, all lines are copied.
|
|
<DT><B>-O</B>
|
|
|
|
<DD>
|
|
Begin assigning to
|
|
<I>array</I>
|
|
|
|
at index
|
|
<I>origin</I>.
|
|
|
|
The default index is 0.
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
Discard the first <I>count</I> lines read.
|
|
<DT><B>-t</B>
|
|
|
|
<DD>
|
|
Remove a trailing <I>delim</I> (default newline) from each line read.
|
|
<DT><B>-u</B>
|
|
|
|
<DD>
|
|
Read lines from file descriptor <I>fd</I> instead of the standard input.
|
|
<DT><B>-C</B>
|
|
|
|
<DD>
|
|
Evaluate
|
|
<I>callback</I>
|
|
|
|
each time <I>quantum</I> lines are read. The <B>-c</B> option specifies
|
|
<I>quantum</I>.
|
|
|
|
<DT><B>-c</B>
|
|
|
|
<DD>
|
|
Specify the number of lines read between each call to
|
|
<I>callback</I>.
|
|
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If
|
|
<B>-C</B>
|
|
|
|
is specified without
|
|
<B>-c</B>,
|
|
|
|
the default quantum is 5000.
|
|
When <I>callback</I> is evaluated, it is supplied the index of the next
|
|
array element to be assigned and the line to be assigned to that element
|
|
as additional arguments.
|
|
<I>callback</I> is evaluated after the line is read but before the
|
|
array element is assigned.
|
|
<P>
|
|
|
|
If not supplied with an explicit origin, <B>mapfile</B> will clear <I>array</I>
|
|
before assigning to it.
|
|
<P>
|
|
|
|
<B>mapfile</B> returns successfully unless an invalid option or option
|
|
argument is supplied, <I>array</I> is invalid or unassignable, or if
|
|
<I>array</I> is not an indexed array.
|
|
</DL>
|
|
|
|
<DT><B>popd</B> [-<B>n</B>] [+<I>n</I>] [-<I>n</I>]<DD>
|
|
Removes entries from the directory stack.
|
|
The elements are numbered from 0 starting at the first directory
|
|
listed by <B>dirs</B>.
|
|
With no arguments, <B>popd</B>
|
|
removes the top directory from the stack, and
|
|
changes to the new top directory.
|
|
Arguments, if supplied, have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
Suppresses the normal change of directory when removing directories
|
|
from the stack, so that only the stack is manipulated.
|
|
<DT><B>+</B><I>n</I><DD>
|
|
Removes the <I>n</I>th entry counting from the left of the list
|
|
shown by
|
|
<B>dirs</B>,
|
|
|
|
starting with zero, from the stack.
|
|
For example:
|
|
|
|
<TT>popd +0</TT>
|
|
removes the first directory,
|
|
|
|
<TT>popd +1</TT>
|
|
the second.
|
|
<DT><B>-</B><I>n</I><DD>
|
|
Removes the <I>n</I>th entry counting from the right of the list
|
|
shown by
|
|
<B>dirs</B>,
|
|
|
|
starting with zero. For example:
|
|
|
|
<TT>popd -0</TT>
|
|
removes the last directory,
|
|
|
|
<TT>popd -1</TT>
|
|
the next to last.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If the top element of the directory stack is modified, and
|
|
the <I>-n</I> option was not supplied, <B>popd</B> uses the <B>cd</B>
|
|
builtin to change to the directory at the top of the stack.
|
|
If the <B>cd</B> fails, <B>popd</B> returns a non-zero value.
|
|
<P>
|
|
|
|
Otherwise,
|
|
<B>popd</B>
|
|
|
|
returns false if an invalid option is encountered, the directory stack
|
|
is empty, or a non-existent directory stack entry is specified.
|
|
<P>
|
|
|
|
If the
|
|
<B>popd</B>
|
|
|
|
command is successful,
|
|
bash runs
|
|
<B>dirs</B>
|
|
|
|
to show the final contents of the directory stack,
|
|
and the return status is 0.
|
|
</DL>
|
|
|
|
<DT><B>printf</B> [<B>-v</B> <I>var</I>] <I>format</I> [<I>arguments</I>]<DD>
|
|
Write the formatted <I>arguments</I> to the standard output under the
|
|
control of the <I>format</I>.
|
|
The <B>-v</B> option causes the output to be assigned to the variable
|
|
<I>var</I> rather than being printed to the standard output.
|
|
<P>
|
|
The <I>format</I> is a character string which contains three types of objects:
|
|
plain characters, which are simply copied to standard output, character
|
|
escape sequences, which are converted and copied to the standard output, and
|
|
format specifications, each of which causes printing of the next successive
|
|
<I>argument</I>.
|
|
In addition to the standard <I>printf</I>(1) format specifications,
|
|
<B>printf</B> interprets the following extensions:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>%b</B>
|
|
|
|
<DD>
|
|
causes
|
|
<B>printf</B> to expand backslash escape sequences in the corresponding
|
|
<I>argument</I>
|
|
in the same way as <B>echo -e</B>.
|
|
<DT><B>%q</B>
|
|
|
|
<DD>
|
|
causes <B>printf</B> to output the corresponding
|
|
<I>argument</I> in a format that can be reused as shell input.
|
|
<DT><B>%Q</B>
|
|
|
|
<DD>
|
|
like <B>%q</B>, but applies any supplied precision to the <I>argument</I>
|
|
before quoting it.
|
|
<DT><B>%(</B><I>datefmt</I>)T
|
|
|
|
<DD>
|
|
causes <B>printf</B> to output the date-time string resulting from using
|
|
<I>datefmt</I> as a format string for <I>strftime</I>(3).
|
|
The corresponding <I>argument</I> is an integer representing the number of
|
|
seconds since the epoch.
|
|
Two special argument values may be used: -1 represents the current
|
|
time, and -2 represents the time the shell was invoked.
|
|
If no argument is specified, conversion behaves as if -1 had been given.
|
|
This is an exception to the usual <B>printf</B> behavior.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The %b, %q, and %T directives all use the field width and precision
|
|
arguments from the format specification and write that many bytes from
|
|
(or use that wide a field for) the expanded argument, which usually
|
|
contains more characters than the original.
|
|
<P>
|
|
|
|
Arguments to non-string format specifiers are treated as C constants,
|
|
except that a leading plus or minus sign is allowed, and if the leading
|
|
character is a single or double quote, the value is the ASCII value of
|
|
the following character.
|
|
<P>
|
|
|
|
The <I>format</I> is reused as necessary to consume all of the <I>arguments</I>.
|
|
If the <I>format</I> requires more <I>arguments</I> than are supplied, the
|
|
extra format specifications behave as if a zero value or null string, as
|
|
appropriate, had been supplied.
|
|
The return value is zero on success, non-zero on failure.
|
|
</DL>
|
|
|
|
<DT><B>pushd</B> [<B>-n</B>] [+<I>n</I>] [-<I>n</I>]<DD>
|
|
|
|
<DT><B>pushd</B> [<B>-n</B>] [<I>dir</I>]<DD>
|
|
|
|
Adds a directory to the top of the directory stack, or rotates
|
|
the stack, making the new top of the stack the current working
|
|
directory.
|
|
With no arguments, <B>pushd</B> exchanges the top two elements of
|
|
the directory stack.
|
|
Arguments, if supplied, have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
Suppresses the normal change of directory when rotating or
|
|
adding directories to the stack, so that only the stack is manipulated.
|
|
<DT><B>+</B><I>n</I><DD>
|
|
Rotates the stack so that the <I>n</I>th directory
|
|
(counting from the left of the list shown by
|
|
<B>dirs</B>,
|
|
|
|
starting with zero)
|
|
is at the top.
|
|
<DT><B>-</B><I>n</I><DD>
|
|
Rotates the stack so that the <I>n</I>th directory
|
|
(counting from the right of the list shown by
|
|
<B>dirs</B>,
|
|
|
|
starting with zero) is at the top.
|
|
<DT><I>dir</I>
|
|
|
|
<DD>
|
|
Adds
|
|
<I>dir</I>
|
|
|
|
to the directory stack at the top
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
After the stack has been modified, if the <B>-n</B> option was not
|
|
supplied, <B>pushd</B> uses the <B>cd</B> builtin to change to the
|
|
directory at the top of the stack.
|
|
If the <B>cd</B> fails, <B>pushd</B> returns a non-zero value.
|
|
<P>
|
|
|
|
Otherwise, if no arguments are supplied,
|
|
<B>pushd</B>
|
|
|
|
returns 0 unless the directory stack is empty.
|
|
When rotating the directory stack,
|
|
<B>pushd</B>
|
|
|
|
returns 0 unless the directory stack is empty or
|
|
a non-existent directory stack element is specified.
|
|
<P>
|
|
|
|
If the
|
|
<B>pushd</B>
|
|
|
|
command is successful,
|
|
bash runs
|
|
<B>dirs</B>
|
|
|
|
to show the final contents of the directory stack.
|
|
</DL>
|
|
|
|
<DT><B>pwd</B> [<B>-LP</B>]<DD>
|
|
Print the absolute pathname of the current working directory.
|
|
The pathname printed contains no symbolic links if the
|
|
<B>-P</B>
|
|
|
|
option is supplied or the
|
|
<B>-o physical</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin command is enabled.
|
|
If the
|
|
<B>-L</B>
|
|
|
|
option is used, the pathname printed may contain symbolic links.
|
|
The return status is 0 unless an error occurs while
|
|
reading the name of the current directory or an
|
|
invalid option is supplied.
|
|
<DT><B>read</B> [<B>-ers</B>] [<B>-a</B> <I>aname</I>] [<B>-d</B> <I>delim</I>] [<B>-i</B> <I>text</I>] [<B>-n</B> <I>nchars</I>] [<B>-N</B> <I>nchars</I>] [<B>-p</B> <I>prompt</I>] [<B>-t</B> <I>timeout</I>] [<B>-u</B> <I>fd</I>] [<I>name</I> ...]<DD>
|
|
One line is read from the standard input, or from the file descriptor
|
|
<I>fd</I> supplied as an argument to the <B>-u</B> option,
|
|
split into words as described
|
|
|
|
above
|
|
under <B>Word Splitting</B>,
|
|
and the first word
|
|
is assigned to the first
|
|
<I>name</I>,
|
|
|
|
the second word to the second
|
|
<I>name</I>,
|
|
|
|
and so on.
|
|
If there are more words than names, the remaining words and their
|
|
intervening delimiters are assigned to the last
|
|
<I>name</I>.
|
|
|
|
If there are fewer words read from the input stream than names,
|
|
the remaining names are assigned empty values.
|
|
The characters in
|
|
<FONT SIZE=-1><B>IFS</B>
|
|
|
|
</FONT>
|
|
are used to split the line into words using the same rules the shell
|
|
uses for expansion (described
|
|
|
|
above
|
|
under <B>Word Splitting</B>).
|
|
The backslash character (<B>\</B>) may be used to remove any special
|
|
meaning for the next character read and for line continuation.
|
|
Options, if supplied, have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-a </B><I>aname</I>
|
|
|
|
<DD>
|
|
The words are assigned to sequential indices
|
|
of the array variable
|
|
<I>aname</I>,
|
|
|
|
starting at 0.
|
|
<I>aname</I>
|
|
|
|
is unset before any new values are assigned.
|
|
Other <I>name</I> arguments are ignored.
|
|
<DT><B>-d </B><I>delim</I>
|
|
|
|
<DD>
|
|
The first character of <I>delim</I> is used to terminate the input line,
|
|
rather than newline.
|
|
If <I>delim</I> is the empty string, <B>read</B> will terminate a line
|
|
when it reads a NUL character.
|
|
<DT><B>-e</B>
|
|
|
|
<DD>
|
|
If the standard input
|
|
is coming from a terminal,
|
|
<B>readline</B>
|
|
|
|
(see
|
|
<FONT SIZE=-1><B>READLINE</B>
|
|
|
|
</FONT>
|
|
|
|
above)
|
|
is used to obtain the line.
|
|
Readline uses the current (or default, if line editing was not previously
|
|
active) editing settings, but uses readline's default filename completion.
|
|
<DT><B>-i </B><I>text</I>
|
|
|
|
<DD>
|
|
If
|
|
<B>readline</B>
|
|
|
|
is being used to read the line, <I>text</I> is placed into the editing
|
|
buffer before editing begins.
|
|
<DT><B>-n </B><I>nchars</I>
|
|
|
|
<DD>
|
|
<B>read</B> returns after reading <I>nchars</I> characters rather than
|
|
waiting for a complete line of input, but honors a delimiter if fewer
|
|
than <I>nchars</I> characters are read before the delimiter.
|
|
<DT><B>-N </B><I>nchars</I>
|
|
|
|
<DD>
|
|
<B>read</B> returns after reading exactly <I>nchars</I> characters rather
|
|
than waiting for a complete line of input, unless EOF is encountered or
|
|
<B>read</B> times out.
|
|
Delimiter characters encountered in the input are
|
|
not treated specially and do not cause <B>read</B> to return until
|
|
<I>nchars</I> characters are read.
|
|
The result is not split on the characters in <B>IFS</B>; the intent is
|
|
that the variable is assigned exactly the characters read
|
|
(with the exception of backslash; see the <B>-r</B> option below).
|
|
<DT><B>-p </B><I>prompt</I>
|
|
|
|
<DD>
|
|
Display <I>prompt</I> on standard error, without a
|
|
trailing newline, before attempting to read any input. The prompt
|
|
is displayed only if input is coming from a terminal.
|
|
<DT><B>-r</B>
|
|
|
|
<DD>
|
|
Backslash does not act as an escape character.
|
|
The backslash is considered to be part of the line.
|
|
In particular, a backslash-newline pair may not then be used as a line
|
|
continuation.
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
Silent mode. If input is coming from a terminal, characters are
|
|
not echoed.
|
|
<DT><B>-t </B><I>timeout</I>
|
|
|
|
<DD>
|
|
Cause <B>read</B> to time out and return failure if a complete line of
|
|
input (or a specified number of characters)
|
|
is not read within <I>timeout</I> seconds.
|
|
<I>timeout</I> may be a decimal number with a fractional portion following
|
|
the decimal point.
|
|
This option is only effective if <B>read</B> is reading input from a
|
|
terminal, pipe, or other special file; it has no effect when reading
|
|
from regular files.
|
|
If <B>read</B> times out, <B>read</B> saves any partial input read into
|
|
the specified variable <I>name</I>.
|
|
If <I>timeout</I> is 0, <B>read</B> returns immediately, without trying to
|
|
read any data.
|
|
The exit status is 0 if input is available on the specified file descriptor,
|
|
or the read will return EOF,
|
|
non-zero otherwise.
|
|
The exit status is greater than 128 if the timeout is exceeded.
|
|
<DT><B>-u </B><I>fd</I>
|
|
|
|
<DD>
|
|
Read input from file descriptor <I>fd</I>.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If no
|
|
<I>names</I>
|
|
|
|
are supplied, the line read,
|
|
without the ending delimiter but otherwise unmodified,
|
|
is assigned to the variable
|
|
<FONT SIZE=-1><B>REPLY</B>.
|
|
|
|
</FONT>
|
|
The exit status is zero, unless end-of-file is encountered, <B>read</B>
|
|
times out (in which case the status is greater than 128),
|
|
a variable assignment error (such as assigning to a readonly variable) occurs,
|
|
or an invalid file descriptor is supplied as the argument to <B>-u</B>.
|
|
</DL>
|
|
|
|
<DT><B>readonly</B> [<B>-aAf</B>] [<B>-p</B>] [<I>name</I>[=<I>word</I>] ...]<DD>
|
|
|
|
The given
|
|
<I>names</I> are marked readonly; the values of these
|
|
<I>names</I>
|
|
|
|
may not be changed by subsequent assignment.
|
|
If the
|
|
<B>-f</B>
|
|
|
|
option is supplied, the functions corresponding to the
|
|
<I>names</I> are so
|
|
marked.
|
|
The
|
|
<B>-a</B>
|
|
|
|
option restricts the variables to indexed arrays; the
|
|
<B>-A</B>
|
|
|
|
option restricts the variables to associative arrays.
|
|
If both options are supplied,
|
|
<B>-A</B>
|
|
|
|
takes precedence.
|
|
If no
|
|
<I>name</I>
|
|
|
|
arguments are given, or if the
|
|
<B>-p</B>
|
|
|
|
option is supplied, a list of all readonly names is printed.
|
|
The other options may be used to restrict the output to a subset of
|
|
the set of readonly names.
|
|
The
|
|
<B>-p</B>
|
|
|
|
option causes output to be displayed in a format that
|
|
may be reused as input.
|
|
If a variable name is followed by =<I>word</I>, the value of
|
|
the variable is set to <I>word</I>.
|
|
The return status is 0 unless an invalid option is encountered,
|
|
one of the
|
|
<I>names</I>
|
|
|
|
is not a valid shell variable name, or
|
|
<B>-f</B>
|
|
|
|
is supplied with a
|
|
<I>name</I>
|
|
|
|
that is not a function.
|
|
<DT><B>return</B> [<I>n</I>]<DD>
|
|
Causes a function to stop executing and return the value specified by
|
|
<I>n</I>
|
|
|
|
to its caller.
|
|
If
|
|
<I>n</I>
|
|
|
|
is omitted, the return status is that of the last command
|
|
executed in the function body.
|
|
If <B>return</B> is executed by a trap handler, the last command used to
|
|
determine the status is the last command executed before the trap handler.
|
|
If <B>return</B> is executed during a <B>DEBUG</B> trap, the last command
|
|
used to determine the status is the last command executed by the trap
|
|
handler before <B>return</B> was invoked.
|
|
If
|
|
<B>return</B>
|
|
|
|
is used outside a function,
|
|
but during execution of a script by the
|
|
<B>.</B>
|
|
|
|
(<B>source</B>) command, it causes the shell to stop executing
|
|
that script and return either
|
|
<I>n</I>
|
|
|
|
or the exit status of the last command executed within the
|
|
script as the exit status of the script.
|
|
If <I>n</I> is supplied, the return value is its least significant
|
|
8 bits.
|
|
The return status is non-zero if
|
|
<B>return</B>
|
|
|
|
is supplied a non-numeric argument, or
|
|
is used outside a
|
|
function and not during execution of a script by <B>.</B> or <B>source</B>.
|
|
Any command associated with the <B>RETURN</B> trap is executed
|
|
before execution resumes after the function or script.
|
|
<DT><B>set</B> [<B>-abefhkmnptuvxBCEHPT</B>] [<B>-o</B> <I>option-name</I>] [<B>--</B>] [<B>-</B>] [<I>arg</I> ...]<DD>
|
|
|
|
<DT><B>set</B> [<B>+abefhkmnptuvxBCEHPT</B>] [<B>+o</B> <I>option-name</I>] [<B>--</B>] [<B>-</B>] [<I>arg</I> ...]<DD>
|
|
|
|
Without options, display the name and value of each shell variable
|
|
in a format that can be reused as input
|
|
for setting or resetting the currently-set variables.
|
|
Read-only variables cannot be reset.
|
|
In <I>posix mode</I>, only shell variables are listed.
|
|
The output is sorted according to the current locale.
|
|
When options are specified, they set or unset shell attributes.
|
|
Any arguments remaining after option processing are treated
|
|
as values for the positional parameters and are assigned, in order, to
|
|
<B>$1</B>,
|
|
|
|
<B>$2</B>,
|
|
|
|
<B>...</B>
|
|
|
|
<B>$</B><I>n</I>.
|
|
|
|
Options, if specified, have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-a</B>
|
|
|
|
<DD>
|
|
Each variable or function that is created or modified is given the
|
|
export attribute and marked for export to the environment of
|
|
subsequent commands.
|
|
<DT><B>-b</B>
|
|
|
|
<DD>
|
|
Report the status of terminated background jobs
|
|
immediately, rather than before the next primary prompt. This is
|
|
effective only when job control is enabled.
|
|
<DT><B>-e</B>
|
|
|
|
<DD>
|
|
Exit immediately if a
|
|
<I>pipeline</I> (which may consist of a single <I>simple command</I>),
|
|
a <I>list</I>,
|
|
or a <I>compound command</I>
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL GRAMMAR</B>
|
|
|
|
</FONT>
|
|
|
|
above),
|
|
exits with a non-zero status.
|
|
The shell does not exit if the
|
|
command that fails is part of the command list immediately following a
|
|
<B>while</B>
|
|
|
|
or
|
|
<B>until</B>
|
|
|
|
keyword,
|
|
part of the test following the
|
|
<B>if</B>
|
|
|
|
or
|
|
<B>elif</B>
|
|
|
|
reserved words, part of any command executed in a
|
|
<B>&&</B>
|
|
|
|
or
|
|
<B>||</B>
|
|
|
|
list except the command following the final <B>&&</B> or <B>||</B>,
|
|
any command in a pipeline but the last,
|
|
or if the command's return value is
|
|
being inverted with
|
|
<B>!</B>.
|
|
|
|
If a compound command other than a subshell
|
|
returns a non-zero status because a command failed
|
|
while <B>-e</B> was being ignored, the shell does not exit.
|
|
A trap on <B>ERR</B>, if set, is executed before the shell exits.
|
|
This option applies to the shell environment and each subshell environment
|
|
separately (see
|
|
<FONT SIZE=-1><B>COMMAND EXECUTION ENVIRONMENT</B>
|
|
|
|
</FONT>
|
|
|
|
above),
|
|
and may cause
|
|
subshells to exit before executing all the commands in the subshell.
|
|
<P>
|
|
|
|
|
|
If a compound command or shell function executes in a context
|
|
where <B>-e</B> is being ignored,
|
|
none of the commands executed within the compound command or function body
|
|
will be affected by the <B>-e</B> setting, even if <B>-e</B> is set
|
|
and a command returns a failure status.
|
|
If a compound command or shell function sets <B>-e</B> while executing in
|
|
a context where <B>-e</B> is ignored, that setting will not have any
|
|
effect until the compound command or the command containing the function
|
|
call completes.
|
|
<DT><B>-f</B>
|
|
|
|
<DD>
|
|
Disable pathname expansion.
|
|
<DT><B>-h</B>
|
|
|
|
<DD>
|
|
Remember the location of commands as they are looked up for execution.
|
|
This is enabled by default.
|
|
<DT><B>-k</B>
|
|
|
|
<DD>
|
|
All arguments in the form of assignment statements
|
|
are placed in the environment for a command, not just
|
|
those that precede the command name.
|
|
<DT><B>-m</B>
|
|
|
|
<DD>
|
|
Monitor mode. Job control is enabled. This option is on
|
|
by default for interactive shells on systems that support
|
|
it (see
|
|
<FONT SIZE=-1><B>JOB CONTROL</B>
|
|
|
|
</FONT>
|
|
|
|
above).
|
|
All processes run in a separate process group.
|
|
When a background job completes, the shell prints a line
|
|
containing its exit status.
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
Read commands but do not execute them.
|
|
This may be used to check a shell script for syntax errors.
|
|
This is ignored by interactive shells.
|
|
<DT><B>-o </B><I>option-name</I>
|
|
|
|
<DD>
|
|
The <I>option-name</I> can be one of the following:
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>allexport</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-a</B>.
|
|
|
|
<DT><B>braceexpand</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-B</B>.
|
|
|
|
<DT><B>emacs</B>
|
|
|
|
<DD>
|
|
Use an emacs-style command line editing interface. This is enabled
|
|
by default when the shell is interactive, unless the shell is started
|
|
with the
|
|
<B>--noediting</B>
|
|
|
|
option.
|
|
This also affects the editing interface used for <B>read -e</B>.
|
|
<DT><B>errexit</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-e</B>.
|
|
|
|
<DT><B>errtrace</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-E</B>.
|
|
|
|
<DT><B>functrace</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-T</B>.
|
|
|
|
<DT><B>hashall</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-h</B>.
|
|
|
|
<DT><B>histexpand</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-H</B>.
|
|
|
|
<DT><B>history</B>
|
|
|
|
<DD>
|
|
Enable command history, as described
|
|
|
|
above
|
|
under
|
|
<FONT SIZE=-1><B>HISTORY</B>.
|
|
|
|
</FONT>
|
|
This option is on by default in interactive shells.
|
|
<DT><B>ignoreeof</B>
|
|
|
|
<DD>
|
|
The effect is as if the shell command
|
|
<TT>IGNOREEOF=10</TT>
|
|
|
|
had been executed
|
|
(see
|
|
<B>Shell Variables</B>
|
|
|
|
|
|
above).
|
|
<DT><B>keyword</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-k</B>.
|
|
|
|
<DT><B>monitor</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-m</B>.
|
|
|
|
<DT><B>noclobber</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-C</B>.
|
|
|
|
<DT><B>noexec</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-n</B>.
|
|
|
|
<DT><B>noglob</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-f</B>.
|
|
|
|
<DT><B>nolog</B>
|
|
|
|
<DD>
|
|
Currently ignored.
|
|
<DT><B>notify</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-b</B>.
|
|
|
|
<DT><B>nounset</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-u</B>.
|
|
|
|
<DT><B>onecmd</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-t</B>.
|
|
|
|
<DT><B>physical</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-P</B>.
|
|
|
|
<DT><B>pipefail</B>
|
|
|
|
<DD>
|
|
If set, the return value of a pipeline is the value of the last
|
|
(rightmost) command to exit with a non-zero status, or zero if all
|
|
commands in the pipeline exit successfully.
|
|
This option is disabled by default.
|
|
<DT><B>posix</B>
|
|
|
|
<DD>
|
|
Change the behavior of
|
|
<B>bash</B>
|
|
|
|
where the default operation differs
|
|
from the POSIX standard to match the standard (<I>posix mode</I>).
|
|
See
|
|
<FONT SIZE=-1><B>SEE ALSO</B>
|
|
|
|
</FONT>
|
|
|
|
below
|
|
for a reference to a document that details how posix mode affects
|
|
bash's behavior.
|
|
<DT><B>privileged</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-p</B>.
|
|
|
|
<DT><B>verbose</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-v</B>.
|
|
|
|
<DT><B>vi</B>
|
|
|
|
<DD>
|
|
Use a vi-style command line editing interface.
|
|
This also affects the editing interface used for <B>read -e</B>.
|
|
<DT><B>xtrace</B>
|
|
|
|
<DD>
|
|
Same as
|
|
<B>-x</B>.
|
|
|
|
<P>
|
|
</DL>
|
|
<P>
|
|
|
|
If
|
|
<B>-o</B>
|
|
|
|
is supplied with no <I>option-name</I>, the values of the current options are
|
|
printed.
|
|
If
|
|
<B>+o</B>
|
|
|
|
is supplied with no <I>option-name</I>, a series of
|
|
<B>set</B>
|
|
|
|
commands to recreate the current option settings is displayed on
|
|
the standard output.
|
|
</DL>
|
|
|
|
<DT><B>-p</B>
|
|
|
|
<DD>
|
|
Turn on
|
|
<I>privileged</I>
|
|
|
|
mode. In this mode, the
|
|
<FONT SIZE=-1><B>$ENV</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>$BASH_ENV</B>
|
|
|
|
</FONT>
|
|
files are not processed, shell functions are not inherited from the
|
|
environment, and the
|
|
<FONT SIZE=-1><B>SHELLOPTS</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>BASHOPTS</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>CDPATH</B>,
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>GLOBIGNORE</B>
|
|
|
|
</FONT>
|
|
variables, if they appear in the environment, are ignored.
|
|
If the shell is started with the effective user (group) id not equal to the
|
|
real user (group) id, and the <B>-p</B> option is not supplied, these actions
|
|
are taken and the effective user id is set to the real user id.
|
|
If the <B>-p</B> option is supplied at startup, the effective user id is
|
|
not reset.
|
|
Turning this option off causes the effective user
|
|
and group ids to be set to the real user and group ids.
|
|
<DT><B>-r</B>
|
|
|
|
<DD>
|
|
Enable restricted shell mode.
|
|
This option cannot be unset once it has been set.
|
|
<DT><B>-t</B>
|
|
|
|
<DD>
|
|
Exit after reading and executing one command.
|
|
<DT><B>-u</B>
|
|
|
|
<DD>
|
|
Treat unset variables and parameters other than the special
|
|
parameters "@" and "*",
|
|
or array variables subscripted with "@" or "*",
|
|
as an error when performing
|
|
parameter expansion. If expansion is attempted on an
|
|
unset variable or parameter, the shell prints an error message, and,
|
|
if not interactive, exits with a non-zero status.
|
|
<DT><B>-v</B>
|
|
|
|
<DD>
|
|
Print shell input lines as they are read.
|
|
<DT><B>-x</B>
|
|
|
|
<DD>
|
|
After expanding each <I>simple command</I>,
|
|
<B>for</B> command, <B>case</B> command, <B>select</B> command, or
|
|
arithmetic <B>for</B> command, display the expanded value of
|
|
<FONT SIZE=-1><B>PS4</B>,
|
|
|
|
</FONT>
|
|
followed by the command and its expanded arguments
|
|
or associated word list.
|
|
<DT><B>-B</B>
|
|
|
|
<DD>
|
|
The shell performs brace expansion (see
|
|
<B>Brace Expansion</B>
|
|
|
|
|
|
above).
|
|
This is on by default.
|
|
<DT><B>-C</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
does not overwrite an existing file with the
|
|
<B>></B>,
|
|
|
|
<B>>&</B>,
|
|
|
|
and
|
|
<B><></B>
|
|
|
|
redirection operators. This may be overridden when
|
|
creating output files by using the redirection operator
|
|
<B>>|</B>
|
|
|
|
instead of
|
|
<B>></B>.
|
|
|
|
<DT><B>-E</B>
|
|
|
|
<DD>
|
|
If set, any trap on <B>ERR</B> is inherited by shell functions, command
|
|
substitutions, and commands executed in a subshell environment.
|
|
The <B>ERR</B> trap is normally not inherited in such cases.
|
|
<DT><B>-H</B>
|
|
|
|
<DD>
|
|
Enable
|
|
<B>!</B>
|
|
|
|
style history substitution. This option is on by
|
|
default when the shell is interactive.
|
|
<DT><B>-P</B>
|
|
|
|
<DD>
|
|
If set, the shell does not resolve symbolic links when executing
|
|
commands such as
|
|
<B>cd</B>
|
|
|
|
that change the current working directory. It uses the
|
|
physical directory structure instead. By default,
|
|
<B>bash</B>
|
|
|
|
follows the logical chain of directories when performing commands
|
|
which change the current directory.
|
|
<DT><B>-T</B>
|
|
|
|
<DD>
|
|
If set, any traps on <B>DEBUG</B> and <B>RETURN</B> are inherited by shell
|
|
functions, command substitutions, and commands executed in a
|
|
subshell environment.
|
|
The <B>DEBUG</B> and <B>RETURN</B> traps are normally not inherited
|
|
in such cases.
|
|
<DT><B>--</B>
|
|
|
|
<DD>
|
|
If no arguments follow this option, then the positional parameters are
|
|
unset. Otherwise, the positional parameters are set to the
|
|
<I>arg</I>s, even if some of them begin with a
|
|
<B>-</B>.
|
|
|
|
<DT><B>-</B>
|
|
|
|
<DD>
|
|
Signal the end of options, cause all remaining <I>arg</I>s to be
|
|
assigned to the positional parameters. The
|
|
<B>-x</B>
|
|
|
|
and
|
|
<B>-v</B>
|
|
|
|
options are turned off.
|
|
If there are no <I>arg</I>s,
|
|
the positional parameters remain unchanged.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
The options are off by default unless otherwise noted.
|
|
Using + rather than - causes these options to be turned off.
|
|
The options can also be specified as arguments to an invocation of
|
|
the shell.
|
|
The current set of options may be found in
|
|
<B>$-</B>.
|
|
|
|
The return status is always true unless an invalid option is encountered.
|
|
</DL>
|
|
|
|
<DT><B>shift</B> [<I>n</I>]<DD>
|
|
The positional parameters from <I>n</I>+1 ... are renamed to
|
|
<B>$1</B>
|
|
|
|
<B>....</B>
|
|
|
|
Parameters represented by the numbers <B>$#</B>
|
|
down to <B>$#</B>-<I>n</I>+1 are unset.
|
|
<I>n</I>
|
|
|
|
must be a non-negative number less than or equal to <B>$#</B>.
|
|
If
|
|
<I>n</I>
|
|
|
|
is 0, no parameters are changed.
|
|
If
|
|
<I>n</I>
|
|
|
|
is not given, it is assumed to be 1.
|
|
If
|
|
<I>n</I>
|
|
|
|
is greater than <B>$#</B>, the positional parameters are not changed.
|
|
The return status is greater than zero if
|
|
<I>n</I>
|
|
|
|
is greater than
|
|
<B>$#</B>
|
|
|
|
or less than zero; otherwise 0.
|
|
<DT><B>shopt</B> [<B>-pqsu</B>] [<B>-o</B>] [<I>optname</I> ...]<DD>
|
|
Toggle the values of settings controlling optional shell behavior.
|
|
The settings can be either those listed below, or, if the
|
|
<B>-o</B>
|
|
|
|
option is used, those available with the
|
|
<B>-o</B>
|
|
|
|
option to the <B>set</B> builtin command.
|
|
With no options, or with the
|
|
<B>-p</B>
|
|
|
|
option, a list of all settable options is displayed, with
|
|
an indication of whether or not each is set;
|
|
if <I>optnames</I> are supplied, the output is restricted to those options.
|
|
The <B>-p</B> option causes output to be displayed in a form that
|
|
may be reused as input.
|
|
Other options have the following meanings:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
Enable (set) each <I>optname</I>.
|
|
<DT><B>-u</B>
|
|
|
|
<DD>
|
|
Disable (unset) each <I>optname</I>.
|
|
<DT><B>-q</B>
|
|
|
|
<DD>
|
|
Suppresses normal output (quiet mode); the return status indicates
|
|
whether the <I>optname</I> is set or unset.
|
|
If multiple <I>optname</I> arguments are given with
|
|
<B>-q</B>,
|
|
|
|
the return status is zero if all <I>optnames</I> are enabled; non-zero
|
|
otherwise.
|
|
<DT><B>-o</B>
|
|
|
|
<DD>
|
|
Restricts the values of <I>optname</I> to be those defined for the
|
|
<B>-o</B>
|
|
|
|
option to the
|
|
<B>set</B>
|
|
|
|
builtin.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If either
|
|
<B>-s</B>
|
|
|
|
or
|
|
<B>-u</B>
|
|
|
|
is used with no <I>optname</I> arguments,
|
|
<B>shopt</B>
|
|
|
|
shows only those options which are set or unset, respectively.
|
|
Unless otherwise noted, the <B>shopt</B> options are disabled (unset)
|
|
by default.
|
|
<P>
|
|
|
|
The return status when listing options is zero if all <I>optnames</I>
|
|
are enabled, non-zero otherwise. When setting or unsetting options,
|
|
the return status is zero unless an <I>optname</I> is not a valid shell
|
|
option.
|
|
<P>
|
|
|
|
The list of <B>shopt</B> options is:
|
|
<P>
|
|
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><B>assoc_expand_once</B>
|
|
|
|
<DD>
|
|
If set, the shell suppresses multiple evaluation of associative array
|
|
subscripts during arithmetic expression evaluation, while executing
|
|
builtins that can perform variable assignments,
|
|
and while executing builtins that perform array dereferencing.
|
|
<DT><B>autocd</B>
|
|
|
|
<DD>
|
|
If set, a command name that is the name of a directory is executed as if
|
|
it were the argument to the <B>cd</B> command.
|
|
This option is only used by interactive shells.
|
|
<DT><B>cdable_vars</B>
|
|
|
|
<DD>
|
|
If set, an argument to the
|
|
<B>cd</B>
|
|
|
|
builtin command that
|
|
is not a directory is assumed to be the name of a variable whose
|
|
value is the directory to change to.
|
|
<DT><B>cdspell</B>
|
|
|
|
<DD>
|
|
If set, minor errors in the spelling of a directory component in a
|
|
<B>cd</B>
|
|
|
|
command will be corrected.
|
|
The errors checked for are transposed characters,
|
|
a missing character, and one character too many.
|
|
If a correction is found, the corrected filename is printed,
|
|
and the command proceeds.
|
|
This option is only used by interactive shells.
|
|
<DT><B>checkhash</B>
|
|
|
|
<DD>
|
|
If set, <B>bash</B> checks that a command found in the hash
|
|
table exists before trying to execute it. If a hashed command no
|
|
longer exists, a normal path search is performed.
|
|
<DT><B>checkjobs</B>
|
|
|
|
<DD>
|
|
If set, <B>bash</B> lists the status of any stopped and running jobs before
|
|
exiting an interactive shell. If any jobs are running, this causes
|
|
the exit to be deferred until a second exit is attempted without an
|
|
intervening command (see
|
|
<FONT SIZE=-1><B>JOB CONTROL</B>
|
|
|
|
</FONT>
|
|
|
|
above).
|
|
The shell always postpones exiting if any jobs are stopped.
|
|
<DT><B>checkwinsize</B>
|
|
|
|
<DD>
|
|
If set, <B>bash</B> checks the window size after each external (non-builtin)
|
|
command and, if necessary, updates the values of
|
|
<FONT SIZE=-1><B>LINES</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>COLUMNS</B>.
|
|
|
|
</FONT>
|
|
This option is enabled by default.
|
|
<DT><B>cmdhist</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
attempts to save all lines of a multiple-line
|
|
command in the same history entry. This allows
|
|
easy re-editing of multi-line commands.
|
|
This option is enabled by default, but only has an effect if command
|
|
history is enabled, as described
|
|
|
|
above
|
|
under
|
|
<FONT SIZE=-1><B>HISTORY</B>.
|
|
|
|
</FONT>
|
|
|
|
<DT><B>compat31</B>
|
|
|
|
<DD>
|
|
<DT><B>compat32</B>
|
|
|
|
<DD>
|
|
<DT><B>compat40</B>
|
|
|
|
<DD>
|
|
<DT><B>compat41</B>
|
|
|
|
<DD>
|
|
<DT><B>compat42</B>
|
|
|
|
<DD>
|
|
<DT><B>compat43</B>
|
|
|
|
<DD>
|
|
<DT><B>compat44</B>
|
|
|
|
<DD>
|
|
<DT><B>compat50</B>
|
|
|
|
<DD>
|
|
|
|
These control aspects of the shell's compatibility mode
|
|
(see
|
|
<FONT SIZE=-1><B>SHELL COMPATIBILITY MODE</B>
|
|
|
|
</FONT>
|
|
|
|
below).
|
|
<DT><B>complete_fullquote</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
quotes all shell metacharacters in filenames and directory names when
|
|
performing completion.
|
|
If not set,
|
|
<B>bash</B>
|
|
|
|
removes metacharacters such as the dollar sign from the set of
|
|
characters that will be quoted in completed filenames
|
|
when these metacharacters appear in shell variable references in words to be
|
|
completed.
|
|
This means that dollar signs in variable names that expand to directories
|
|
will not be quoted;
|
|
however, any dollar signs appearing in filenames will not be quoted, either.
|
|
This is active only when bash is using backslashes to quote completed
|
|
filenames.
|
|
This variable is set by default, which is the default bash behavior in
|
|
versions through 4.2.
|
|
<DT><B>direxpand</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
replaces directory names with the results of word expansion when performing
|
|
filename completion. This changes the contents of the readline editing
|
|
buffer.
|
|
If not set,
|
|
<B>bash</B>
|
|
|
|
attempts to preserve what the user typed.
|
|
<DT><B>dirspell</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
attempts spelling correction on directory names during word completion
|
|
if the directory name initially supplied does not exist.
|
|
<DT><B>dotglob</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
includes filenames beginning with a `.' in the results of pathname
|
|
expansion.
|
|
The filenames
|
|
<B>``.''</B>
|
|
|
|
and
|
|
<B>``..''</B>
|
|
|
|
must always be matched explicitly, even if
|
|
<B>dotglob</B>
|
|
|
|
is set.
|
|
<DT><B>execfail</B>
|
|
|
|
<DD>
|
|
If set, a non-interactive shell will not exit if
|
|
it cannot execute the file specified as an argument to the
|
|
<B>exec</B>
|
|
|
|
builtin command. An interactive shell does not exit if
|
|
<B>exec</B>
|
|
|
|
fails.
|
|
<DT><B>expand_aliases</B>
|
|
|
|
<DD>
|
|
If set, aliases are expanded as described
|
|
|
|
above
|
|
under
|
|
<FONT SIZE=-1><B>ALIASES</B>.
|
|
|
|
</FONT>
|
|
This option is enabled by default for interactive shells.
|
|
<DT><B>extdebug</B>
|
|
|
|
<DD>
|
|
If set at shell invocation,
|
|
or in a shell startup file,
|
|
arrange to execute the debugger profile
|
|
before the shell starts, identical to the <B>--debugger</B> option.
|
|
If set after invocation, behavior intended for use by debuggers is enabled:
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT><B>1.</B>
|
|
|
|
<DD>
|
|
The <B>-F</B> option to the <B>declare</B> builtin displays the source
|
|
file name and line number corresponding to each function name supplied
|
|
as an argument.
|
|
<DT><B>2.</B>
|
|
|
|
<DD>
|
|
If the command run by the <B>DEBUG</B> trap returns a non-zero value, the
|
|
next command is skipped and not executed.
|
|
<DT><B>3.</B>
|
|
|
|
<DD>
|
|
If the command run by the <B>DEBUG</B> trap returns a value of 2, and the
|
|
shell is executing in a subroutine (a shell function or a shell script
|
|
executed by the <B>.</B> or <B>source</B> builtins), the shell simulates
|
|
a call to <B>return</B>.
|
|
<DT><B>4.</B>
|
|
|
|
<DD>
|
|
<FONT SIZE=-1><B>BASH_ARGC</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>BASH_ARGV</B>
|
|
|
|
</FONT>
|
|
are updated as described in their descriptions
|
|
|
|
above).
|
|
<DT><B>5.</B>
|
|
|
|
<DD>
|
|
Function tracing is enabled: command substitution, shell functions, and
|
|
subshells invoked with <B>(</B> <I>command</I> <B>)</B> inherit the
|
|
<B>DEBUG</B> and <B>RETURN</B> traps.
|
|
<DT><B>6.</B>
|
|
|
|
<DD>
|
|
Error tracing is enabled: command substitution, shell functions, and
|
|
subshells invoked with <B>(</B> <I>command</I> <B>)</B> inherit the
|
|
<B>ERR</B> trap.
|
|
</DL></DL>
|
|
|
|
<DT><B>extglob</B>
|
|
|
|
<DD>
|
|
If set, the extended pattern matching features described
|
|
|
|
above
|
|
under
|
|
<B>Pathname Expansion</B> are enabled.
|
|
<DT><B>extquote</B>
|
|
|
|
<DD>
|
|
If set, <B>$</B>aq<I>string</I>aq and <B>$</B>"<I>string</I>" quoting is
|
|
performed within <B>${</B><I>parameter</I><B>}</B> expansions
|
|
enclosed in double quotes. This option is enabled by default.
|
|
<DT><B>failglob</B>
|
|
|
|
<DD>
|
|
If set, patterns which fail to match filenames during pathname expansion
|
|
result in an expansion error.
|
|
<DT><B>force_fignore</B>
|
|
|
|
<DD>
|
|
If set, the suffixes specified by the
|
|
<FONT SIZE=-1><B>FIGNORE</B>
|
|
|
|
</FONT>
|
|
shell variable
|
|
cause words to be ignored when performing word completion even if
|
|
the ignored words are the only possible completions.
|
|
See
|
|
<FONT SIZE=-1><B>SHELL VARIABLES</B></FONT>
|
|
|
|
above
|
|
for a description of
|
|
<FONT SIZE=-1><B>FIGNORE</B>.
|
|
|
|
</FONT>
|
|
This option is enabled by default.
|
|
<DT><B>globasciiranges</B>
|
|
|
|
<DD>
|
|
If set, range expressions used in pattern matching bracket expressions (see
|
|
<FONT SIZE=-1><B>Pattern Matching</B>
|
|
|
|
</FONT>
|
|
|
|
above)
|
|
behave as if in the traditional C locale when performing
|
|
comparisons. That is, the current locale's collating sequence
|
|
is not taken into account, so
|
|
<B>b</B>
|
|
|
|
will not collate between
|
|
<B>A</B>
|
|
|
|
and
|
|
<B>B</B>,
|
|
|
|
and upper-case and lower-case ASCII characters will collate together.
|
|
<DT><B>globskipdots</B>
|
|
|
|
<DD>
|
|
If set, pathname expansion will never match the filenames
|
|
<B>``.''</B>
|
|
|
|
and
|
|
<B>``..''</B>,
|
|
|
|
even if the pattern begins with a
|
|
<B>``.''</B>.
|
|
|
|
This option is enabled by default.
|
|
<DT><B>globstar</B>
|
|
|
|
<DD>
|
|
If set, the pattern <B>**</B> used in a pathname expansion context will
|
|
match all files and zero or more directories and subdirectories.
|
|
If the pattern is followed by a <B>/</B>, only directories and
|
|
subdirectories match.
|
|
<DT><B>gnu_errfmt</B>
|
|
|
|
<DD>
|
|
If set, shell error messages are written in the standard GNU error
|
|
message format.
|
|
<DT><B>histappend</B>
|
|
|
|
<DD>
|
|
If set, the history list is appended to the file named by the value
|
|
of the
|
|
<FONT SIZE=-1><B>HISTFILE</B>
|
|
|
|
</FONT>
|
|
variable when the shell exits, rather than overwriting the file.
|
|
<DT><B>histreedit</B>
|
|
|
|
<DD>
|
|
If set, and
|
|
<B>readline</B>
|
|
|
|
is being used, a user is given the opportunity to re-edit a
|
|
failed history substitution.
|
|
<DT><B>histverify</B>
|
|
|
|
<DD>
|
|
If set, and
|
|
<B>readline</B>
|
|
|
|
is being used, the results of history substitution are not immediately
|
|
passed to the shell parser. Instead, the resulting line is loaded into
|
|
the <B>readline</B> editing buffer, allowing further modification.
|
|
<DT><B>hostcomplete</B>
|
|
|
|
<DD>
|
|
If set, and
|
|
<B>readline</B>
|
|
|
|
is being used, <B>bash</B> will attempt to perform hostname completion when a
|
|
word containing a <B>@</B> is being completed (see
|
|
<B>Completing</B>
|
|
|
|
under
|
|
<FONT SIZE=-1><B>READLINE</B>
|
|
|
|
</FONT>
|
|
|
|
above).
|
|
This is enabled by default.
|
|
<DT><B>huponexit</B>
|
|
|
|
<DD>
|
|
If set, <B>bash</B> will send
|
|
<FONT SIZE=-1><B>SIGHUP</B>
|
|
|
|
</FONT>
|
|
to all jobs when an interactive login shell exits.
|
|
<DT><B>inherit_errexit</B>
|
|
|
|
<DD>
|
|
If set, command substitution inherits the value of the <B>errexit</B> option,
|
|
instead of unsetting it in the subshell environment.
|
|
This option is enabled when <I>posix mode</I> is enabled.
|
|
<DT><B>interactive_comments</B>
|
|
|
|
<DD>
|
|
If set, allow a word beginning with
|
|
<B>#</B>
|
|
|
|
to cause that word and all remaining characters on that
|
|
line to be ignored in an interactive shell (see
|
|
<FONT SIZE=-1><B>COMMENTS</B>
|
|
|
|
</FONT>
|
|
|
|
above).
|
|
This option is enabled by default.
|
|
<DT><B>lastpipe</B>
|
|
|
|
<DD>
|
|
If set, and job control is not active, the shell runs the last command of
|
|
a pipeline not executed in the background in the current shell environment.
|
|
<DT><B>lithist</B>
|
|
|
|
<DD>
|
|
If set, and the
|
|
<B>cmdhist</B>
|
|
|
|
option is enabled, multi-line commands are saved to the history with
|
|
embedded newlines rather than using semicolon separators where possible.
|
|
<DT><B>localvar_inherit</B>
|
|
|
|
<DD>
|
|
If set, local variables inherit the value and attributes of a variable of
|
|
the same name that exists at a previous scope before any new value is
|
|
assigned. The nameref attribute is not inherited.
|
|
<DT><B>localvar_unset</B>
|
|
|
|
<DD>
|
|
If set, calling <B>unset</B> on local variables in previous function scopes
|
|
marks them so subsequent lookups find them unset until that function
|
|
returns. This is identical to the behavior of unsetting local variables
|
|
at the current function scope.
|
|
<DT><B>login_shell</B>
|
|
|
|
<DD>
|
|
The shell sets this option if it is started as a login shell (see
|
|
<FONT SIZE=-1><B>INVOCATION</B>
|
|
|
|
</FONT>
|
|
|
|
above).
|
|
The value may not be changed.
|
|
<DT><B>mailwarn</B>
|
|
|
|
<DD>
|
|
If set, and a file that <B>bash</B> is checking for mail has been
|
|
accessed since the last time it was checked, the message ``The mail in
|
|
<I>mailfile</I> has been read'' is displayed.
|
|
<DT><B>no_empty_cmd_completion</B>
|
|
|
|
<DD>
|
|
If set, and
|
|
<B>readline</B>
|
|
|
|
is being used,
|
|
<B>bash</B>
|
|
|
|
will not attempt to search the
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
for possible completions when
|
|
completion is attempted on an empty line.
|
|
<DT><B>nocaseglob</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
matches filenames in a case-insensitive fashion when performing pathname
|
|
expansion (see
|
|
<B>Pathname Expansion</B>
|
|
|
|
|
|
above).
|
|
<DT><B>nocasematch</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
matches patterns in a case-insensitive fashion when performing matching
|
|
while executing <B>case</B> or <B>[[</B> conditional commands,
|
|
when performing pattern substitution word expansions,
|
|
or when filtering possible completions as part of programmable completion.
|
|
<DT><B>noexpand_translation</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
encloses the translated results of $"..." quoting in single quotes
|
|
instead of double quotes.
|
|
If the string is not translated, this has no effect.
|
|
<DT><B>nullglob</B>
|
|
|
|
<DD>
|
|
If set,
|
|
<B>bash</B>
|
|
|
|
allows patterns which match no
|
|
files (see
|
|
<B>Pathname Expansion</B>
|
|
|
|
|
|
above)
|
|
to expand to a null string, rather than themselves.
|
|
<DT><B>patsub_replacement</B>
|
|
|
|
<DD>
|
|
If set, <B>bash</B>
|
|
expands occurrences of <B>&</B> in the replacement string of pattern
|
|
substitution to the text matched by the pattern, as described
|
|
under <B>Parameter Expansion</B>
|
|
|
|
above.
|
|
This option is enabled by default.
|
|
<DT><B>progcomp</B>
|
|
|
|
<DD>
|
|
If set, the programmable completion facilities (see
|
|
<B>Programmable Completion</B>
|
|
|
|
above)
|
|
are enabled.
|
|
This option is enabled by default.
|
|
<DT><B>progcomp_alias</B>
|
|
|
|
<DD>
|
|
If set, and programmable completion is enabled, <B>bash</B> treats a command
|
|
name that doesn't have any completions as a possible alias and attempts
|
|
alias expansion. If it has an alias, <B>bash</B> attempts programmable
|
|
completion using the command word resulting from the expanded alias.
|
|
<DT><B>promptvars</B>
|
|
|
|
<DD>
|
|
If set, prompt strings undergo
|
|
parameter expansion, command substitution, arithmetic
|
|
expansion, and quote removal after being expanded as described in
|
|
<FONT SIZE=-1><B>PROMPTING</B>
|
|
|
|
</FONT>
|
|
|
|
above.
|
|
This option is enabled by default.
|
|
<DT><B>restricted_shell</B>
|
|
|
|
<DD>
|
|
The shell sets this option if it is started in restricted mode
|
|
(see
|
|
<FONT SIZE=-1><B>RESTRICTED SHELL</B>
|
|
|
|
</FONT>
|
|
|
|
below).
|
|
The value may not be changed.
|
|
This is not reset when the startup files are executed, allowing
|
|
the startup files to discover whether or not a shell is restricted.
|
|
<DT><B>shift_verbose</B>
|
|
|
|
<DD>
|
|
If set, the
|
|
<B>shift</B>
|
|
|
|
builtin prints an error message when the shift count exceeds the
|
|
number of positional parameters.
|
|
<DT><B>sourcepath</B>
|
|
|
|
<DD>
|
|
If set, the
|
|
<B>.</B> (<B>source</B>) builtin uses the value of
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
to find the directory containing the file supplied as an argument.
|
|
This option is enabled by default.
|
|
<DT><B>varredir_close</B>
|
|
|
|
<DD>
|
|
If set, the shell automatically closes file descriptors assigned using the
|
|
<I>{varname}</I> redirection syntax (see
|
|
<FONT SIZE=-1><B>REDIRECTION</B>
|
|
|
|
</FONT>
|
|
|
|
above)
|
|
instead of leaving them open when the command completes.
|
|
<DT><B>xpg_echo</B>
|
|
|
|
<DD>
|
|
If set, the <B>echo</B> builtin expands backslash-escape sequences
|
|
by default.
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>suspend</B> [<B>-f</B>]<DD>
|
|
Suspend the execution of this shell until it receives a
|
|
<FONT SIZE=-1><B>SIGCONT</B>
|
|
|
|
</FONT>
|
|
signal. A login shell,
|
|
or a shell without job control enabled,
|
|
cannot be suspended; the
|
|
<B>-f</B>
|
|
|
|
option can be used to override this and force the suspension.
|
|
The return status is 0 unless the shell is a login shell
|
|
or job control is not enabled
|
|
and
|
|
<B>-f</B>
|
|
|
|
is not supplied.
|
|
<DT><B>test</B> <I>expr</I><DD>
|
|
|
|
<DT><B>[</B> <I>expr</I> <B>]</B><DD>
|
|
Return a status of 0 (true) or 1 (false) depending on
|
|
the evaluation of the conditional expression
|
|
<I>expr</I>.
|
|
|
|
Each operator and operand must be a separate argument.
|
|
Expressions are composed of the primaries described
|
|
|
|
above
|
|
under
|
|
<FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>.
|
|
|
|
</FONT>
|
|
<B>test</B> does not accept any options, nor does it accept and ignore
|
|
an argument of <B>--</B> as signifying the end of options.
|
|
<P>
|
|
|
|
|
|
Expressions may be combined using the following operators, listed
|
|
in decreasing order of precedence.
|
|
The evaluation depends on the number of arguments; see below.
|
|
Operator precedence is used when there are five or more arguments.
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>! </B><I>expr</I>
|
|
|
|
<DD>
|
|
True if
|
|
<I>expr</I>
|
|
|
|
is false.
|
|
<DT><B>( </B><I>expr</I> )
|
|
|
|
<DD>
|
|
Returns the value of <I>expr</I>.
|
|
This may be used to override the normal precedence of operators.
|
|
<DT><I>expr1</I> -<B>a</B> <I>expr2</I><DD>
|
|
True if both
|
|
<I>expr1</I>
|
|
|
|
and
|
|
<I>expr2</I>
|
|
|
|
are true.
|
|
<DT><I>expr1</I> -<B>o</B> <I>expr2</I><DD>
|
|
True if either
|
|
<I>expr1</I>
|
|
|
|
or
|
|
<I>expr2</I>
|
|
|
|
is true.
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
<B>test</B> and <B>[</B> evaluate conditional
|
|
expressions using a set of rules based on the number of arguments.
|
|
<P>
|
|
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT>0 arguments<DD>
|
|
The expression is false.
|
|
<DT>1 argument<DD>
|
|
The expression is true if and only if the argument is not null.
|
|
<DT>2 arguments<DD>
|
|
If the first argument is <B>!</B>, the expression is true if and
|
|
only if the second argument is null.
|
|
If the first argument is one of the unary conditional operators listed
|
|
|
|
above
|
|
under
|
|
<FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>,
|
|
|
|
</FONT>
|
|
the expression is true if the unary test is true.
|
|
If the first argument is not a valid unary conditional operator, the expression
|
|
is false.
|
|
<DT>3 arguments<DD>
|
|
The following conditions are applied in the order listed.
|
|
If the second argument is one of the binary conditional operators listed
|
|
|
|
above
|
|
under
|
|
<FONT SIZE=-1><B>CONDITIONAL EXPRESSIONS</B>,
|
|
|
|
</FONT>
|
|
the result of the expression is the result of the binary test using
|
|
the first and third arguments as operands.
|
|
The <B>-a</B> and <B>-o</B> operators are considered binary operators
|
|
when there are three arguments.
|
|
If the first argument is <B>!</B>, the value is the negation of
|
|
the two-argument test using the second and third arguments.
|
|
If the first argument is exactly <B>(</B> and the third argument is
|
|
exactly <B>)</B>, the result is the one-argument test of the second
|
|
argument.
|
|
Otherwise, the expression is false.
|
|
<DT>4 arguments<DD>
|
|
The following conditions are applied in the order listed.
|
|
If the first argument is <B>!</B>, the result is the negation of
|
|
the three-argument expression composed of the remaining arguments.
|
|
the two-argument test using the second and third arguments.
|
|
If the first argument is exactly <B>(</B> and the fourth argument is
|
|
exactly <B>)</B>, the result is the two-argument test of the second
|
|
and third arguments.
|
|
Otherwise, the expression is parsed and evaluated according to
|
|
precedence using the rules listed above.
|
|
<DT>5 or more arguments<DD>
|
|
The expression is parsed and evaluated according to precedence
|
|
using the rules listed above.
|
|
<P>
|
|
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
When used with <B>test</B> or <B>[</B>, the <B><</B> and <B>></B> operators
|
|
sort lexicographically using ASCII ordering.
|
|
</DL>
|
|
|
|
|
|
<DT><B>times</B>
|
|
|
|
<DD>
|
|
Print the accumulated user and system times for the shell and
|
|
for processes run from the shell. The return status is 0.
|
|
<DT><B>trap</B> [<B>-lp</B>] [[<I>arg</I>] <I>sigspec</I> ...]<DD>
|
|
The command
|
|
<I>arg</I>
|
|
|
|
is to be read and executed when the shell receives
|
|
signal(s)
|
|
<I>sigspec</I>.
|
|
|
|
If
|
|
<I>arg</I>
|
|
|
|
is absent (and there is a single <I>sigspec</I>) or
|
|
<B>-</B>,
|
|
|
|
each specified signal is
|
|
reset to its original disposition (the value it had
|
|
upon entrance to the shell).
|
|
If
|
|
<I>arg</I>
|
|
|
|
is the null string the signal specified by each
|
|
<I>sigspec</I>
|
|
|
|
is ignored by the shell and by the commands it invokes.
|
|
If
|
|
<I>arg</I>
|
|
|
|
is not present and
|
|
<B>-p</B>
|
|
|
|
has been supplied, then the trap commands associated with each
|
|
<I>sigspec</I>
|
|
|
|
are displayed.
|
|
If no arguments are supplied or if only
|
|
<B>-p</B>
|
|
|
|
is given,
|
|
<B>trap</B>
|
|
|
|
prints the list of commands associated with each signal.
|
|
The
|
|
<B>-l</B>
|
|
|
|
option causes the shell to print a list of signal names and
|
|
their corresponding numbers.
|
|
Each
|
|
<I>sigspec</I>
|
|
|
|
is either
|
|
a signal name defined in <<I>signal.h</I>>, or a signal number.
|
|
Signal names are case insensitive and the
|
|
<FONT SIZE=-1><B>SIG</B>
|
|
|
|
</FONT>
|
|
prefix is optional.
|
|
<P>
|
|
|
|
|
|
If a
|
|
<I>sigspec</I>
|
|
|
|
is
|
|
<FONT SIZE=-1><B>EXIT</B>
|
|
|
|
</FONT>
|
|
(0) the command
|
|
<I>arg</I>
|
|
|
|
is executed on exit from the shell.
|
|
If a
|
|
<I>sigspec</I>
|
|
|
|
is
|
|
<FONT SIZE=-1><B>DEBUG</B>,
|
|
|
|
</FONT>
|
|
the command
|
|
<I>arg</I>
|
|
|
|
is executed before every <I>simple command</I>, <I>for</I> command,
|
|
<I>case</I> command, <I>select</I> command, every arithmetic <I>for</I>
|
|
command, and before the first command executes in a shell function (see
|
|
<FONT SIZE=-1><B>SHELL GRAMMAR</B>
|
|
|
|
</FONT>
|
|
|
|
above).
|
|
Refer to the description of the <B>extdebug</B> option to the
|
|
<B>shopt</B> builtin for details of its effect on the <B>DEBUG</B> trap.
|
|
If a
|
|
<I>sigspec</I>
|
|
|
|
is
|
|
<FONT SIZE=-1><B>RETURN</B>,
|
|
|
|
</FONT>
|
|
the command
|
|
<I>arg</I>
|
|
|
|
is executed each time a shell function or a script executed with
|
|
the <B>.</B> or <B>source</B> builtins finishes executing.
|
|
<P>
|
|
|
|
|
|
If a
|
|
<I>sigspec</I>
|
|
|
|
is
|
|
<FONT SIZE=-1><B>ERR</B>,
|
|
|
|
</FONT>
|
|
the command
|
|
<I>arg</I>
|
|
|
|
is executed whenever
|
|
a pipeline (which may consist of a single simple
|
|
command), a list, or a compound command returns a
|
|
non-zero exit status,
|
|
subject to the following conditions.
|
|
The
|
|
<FONT SIZE=-1><B>ERR</B>
|
|
|
|
</FONT>
|
|
trap is not executed if the failed
|
|
command is part of the command list immediately following a
|
|
<B>while</B>
|
|
|
|
or
|
|
<B>until</B>
|
|
|
|
keyword,
|
|
part of the test in an
|
|
<I>if</I>
|
|
|
|
statement, part of a command executed in a
|
|
<B>&&</B>
|
|
|
|
or
|
|
<B>||</B>
|
|
|
|
list except the command following the final <B>&&</B> or <B>||</B>,
|
|
any command in a pipeline but the last,
|
|
or if the command's return value is
|
|
being inverted using
|
|
<B>!</B>.
|
|
|
|
These are the same conditions obeyed by the <B>errexit</B> (<B>-e</B>) option.
|
|
<P>
|
|
|
|
|
|
Signals ignored upon entry to the shell cannot be trapped or reset.
|
|
Trapped signals that are not being ignored are reset to their original
|
|
values in a subshell or subshell environment when one is created.
|
|
The return status is false if any
|
|
<I>sigspec</I>
|
|
|
|
is invalid; otherwise
|
|
<B>trap</B>
|
|
|
|
returns true.
|
|
<DT><B>type</B> [<B>-aftpP</B>] <I>name</I> [<I>name</I> ...]<DD>
|
|
With no options,
|
|
indicate how each
|
|
<I>name</I>
|
|
|
|
would be interpreted if used as a command name.
|
|
If the
|
|
<B>-t</B>
|
|
|
|
option is used,
|
|
<B>type</B>
|
|
|
|
prints a string which is one of
|
|
<I>alias</I>,
|
|
|
|
<I>keyword</I>,
|
|
|
|
<I>function</I>,
|
|
|
|
<I>builtin</I>,
|
|
|
|
or
|
|
<I>file</I>
|
|
|
|
if
|
|
<I>name</I>
|
|
|
|
is an alias, shell reserved word, function, builtin, or disk file,
|
|
respectively.
|
|
If the
|
|
<I>name</I>
|
|
|
|
is not found, then nothing is printed, and an exit status of false
|
|
is returned.
|
|
If the
|
|
<B>-p</B>
|
|
|
|
option is used,
|
|
<B>type</B>
|
|
|
|
either returns the name of the disk file
|
|
that would be executed if
|
|
<I>name</I>
|
|
|
|
were specified as a command name,
|
|
or nothing if
|
|
<TT>type -t name</TT>
|
|
|
|
would not return
|
|
<I>file</I>.
|
|
|
|
The
|
|
<B>-P</B>
|
|
|
|
option forces a
|
|
<FONT SIZE=-1><B>PATH</B>
|
|
|
|
</FONT>
|
|
search for each <I>name</I>, even if
|
|
<TT>type -t name</TT>
|
|
|
|
would not return
|
|
<I>file</I>.
|
|
|
|
If a command is hashed,
|
|
<B>-p</B>
|
|
|
|
and
|
|
<B>-P</B>
|
|
|
|
print the hashed value, which is not necessarily the file that appears
|
|
first in
|
|
<FONT SIZE=-1><B>PATH</B>.
|
|
|
|
</FONT>
|
|
If the
|
|
<B>-a</B>
|
|
|
|
option is used,
|
|
<B>type</B>
|
|
|
|
prints all of the places that contain
|
|
an executable named
|
|
<I>name</I>.
|
|
|
|
This includes aliases and functions,
|
|
if and only if the
|
|
<B>-p</B>
|
|
|
|
option is not also used.
|
|
The table of hashed commands is not consulted
|
|
when using
|
|
<B>-a</B>.
|
|
|
|
The
|
|
<B>-f</B>
|
|
|
|
option suppresses shell function lookup, as with the <B>command</B> builtin.
|
|
<B>type</B>
|
|
|
|
returns true if all of the arguments are found, false if
|
|
any are not found.
|
|
<DT><B>ulimit</B> [<B>-HS</B>] <B>-a</B><DD>
|
|
|
|
<DT><B>ulimit</B> [<B>-HS</B>] [<B>-bcdefiklmnpqrstuvxPRT</B> [<I>limit</I>]]<DD>
|
|
|
|
Provides control over the resources available to the shell and to
|
|
processes started by it, on systems that allow such control.
|
|
The <B>-H</B> and <B>-S</B> options specify that the hard or soft limit is
|
|
set for the given resource.
|
|
A hard limit cannot be increased by a non-root user once it is set;
|
|
a soft limit may be increased up to the value of the hard limit.
|
|
If neither <B>-H</B> nor <B>-S</B> is specified, both the soft and hard
|
|
limits are set.
|
|
The value of
|
|
<I>limit</I>
|
|
|
|
can be a number in the unit specified for the resource
|
|
or one of the special values
|
|
<B>hard</B>,
|
|
|
|
<B>soft</B>,
|
|
|
|
or
|
|
<B>unlimited</B>,
|
|
|
|
which stand for the current hard limit, the current soft limit, and
|
|
no limit, respectively.
|
|
If
|
|
<I>limit</I>
|
|
|
|
is omitted, the current value of the soft limit of the resource is
|
|
printed, unless the <B>-H</B> option is given. When more than one
|
|
resource is specified, the limit name and unit, if appropriate,
|
|
are printed before the value.
|
|
Other options are interpreted as follows:
|
|
<DL COMPACT><DT><DD>
|
|
|
|
<DL COMPACT>
|
|
<DT><B>-a</B>
|
|
|
|
<DD>
|
|
All current limits are reported; no limits are set
|
|
<DT><B>-b</B>
|
|
|
|
<DD>
|
|
The maximum socket buffer size
|
|
<DT><B>-c</B>
|
|
|
|
<DD>
|
|
The maximum size of core files created
|
|
<DT><B>-d</B>
|
|
|
|
<DD>
|
|
The maximum size of a process's data segment
|
|
<DT><B>-e</B>
|
|
|
|
<DD>
|
|
The maximum scheduling priority ("nice")
|
|
<DT><B>-f</B>
|
|
|
|
<DD>
|
|
The maximum size of files written by the shell and its children
|
|
<DT><B>-i</B>
|
|
|
|
<DD>
|
|
The maximum number of pending signals
|
|
<DT><B>-k</B>
|
|
|
|
<DD>
|
|
The maximum number of kqueues that may be allocated
|
|
<DT><B>-l</B>
|
|
|
|
<DD>
|
|
The maximum size that may be locked into memory
|
|
<DT><B>-m</B>
|
|
|
|
<DD>
|
|
The maximum resident set size (many systems do not honor this limit)
|
|
<DT><B>-n</B>
|
|
|
|
<DD>
|
|
The maximum number of open file descriptors (most systems do not
|
|
allow this value to be set)
|
|
<DT><B>-p</B>
|
|
|
|
<DD>
|
|
The pipe size in 512-byte blocks (this may not be set)
|
|
<DT><B>-q</B>
|
|
|
|
<DD>
|
|
The maximum number of bytes in POSIX message queues
|
|
<DT><B>-r</B>
|
|
|
|
<DD>
|
|
The maximum real-time scheduling priority
|
|
<DT><B>-s</B>
|
|
|
|
<DD>
|
|
The maximum stack size
|
|
<DT><B>-t</B>
|
|
|
|
<DD>
|
|
The maximum amount of cpu time in seconds
|
|
<DT><B>-u</B>
|
|
|
|
<DD>
|
|
The maximum number of processes available to a single user
|
|
<DT><B>-v</B>
|
|
|
|
<DD>
|
|
The maximum amount of virtual memory available to the shell and, on
|
|
some systems, to its children
|
|
<DT><B>-x</B>
|
|
|
|
<DD>
|
|
The maximum number of file locks
|
|
<DT><B>-P</B>
|
|
|
|
<DD>
|
|
The maximum number of pseudoterminals
|
|
<DT><B>-R</B>
|
|
|
|
<DD>
|
|
The maximum time a real-time process can run before blocking, in microseconds
|
|
<DT><B>-T</B>
|
|
|
|
<DD>
|
|
The maximum number of threads
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
If
|
|
<I>limit</I>
|
|
|
|
is given, and the
|
|
<B>-a</B>
|
|
|
|
option is not used,
|
|
<I>limit</I> is the new value of the specified resource.
|
|
If no option is given, then
|
|
<B>-f</B>
|
|
|
|
is assumed. Values are in 1024-byte increments, except for
|
|
<B>-t</B>,
|
|
|
|
which is in seconds;
|
|
<B>-R</B>,
|
|
|
|
which is in microseconds;
|
|
<B>-p</B>,
|
|
|
|
which is in units of 512-byte blocks;
|
|
<B>-P</B>,
|
|
|
|
<B>-T</B>,
|
|
|
|
<B>-b</B>,
|
|
|
|
<B>-k</B>,
|
|
|
|
<B>-n</B>,
|
|
|
|
and
|
|
<B>-u</B>,
|
|
|
|
which are unscaled values;
|
|
and, when in posix mode,
|
|
<B>-c</B>
|
|
|
|
and
|
|
<B>-f</B>,
|
|
|
|
which are in 512-byte increments.
|
|
The return status is 0 unless an invalid option or argument is supplied,
|
|
or an error occurs while setting a new limit.
|
|
</DL>
|
|
|
|
<DT><B>umask</B> [<B>-p</B>] [<B>-S</B>] [<I>mode</I>]<DD>
|
|
The user file-creation mask is set to
|
|
<I>mode</I>.
|
|
|
|
If
|
|
<I>mode</I>
|
|
|
|
begins with a digit, it
|
|
is interpreted as an octal number; otherwise
|
|
it is interpreted as a symbolic mode mask similar
|
|
to that accepted by
|
|
<I>chmod</I>(1).
|
|
|
|
If
|
|
<I>mode</I>
|
|
|
|
is omitted, the current value of the mask is printed.
|
|
The
|
|
<B>-S</B>
|
|
|
|
option causes the mask to be printed in symbolic form; the
|
|
default output is an octal number.
|
|
If the
|
|
<B>-p</B>
|
|
|
|
option is supplied, and
|
|
<I>mode</I>
|
|
|
|
is omitted, the output is in a form that may be reused as input.
|
|
The return status is 0 if the mode was successfully changed or if
|
|
no <I>mode</I> argument was supplied, and false otherwise.
|
|
<DT><B>unalias</B> [-<B>a</B>] [<I>name</I> ...]<DD>
|
|
Remove each <I>name</I> from the list of defined aliases. If
|
|
<B>-a</B>
|
|
|
|
is supplied, all alias definitions are removed. The return
|
|
value is true unless a supplied
|
|
<I>name</I>
|
|
|
|
is not a defined alias.
|
|
<DT><B>unset</B> [-<B>fv</B>] [-<B>n</B>] [<I>name</I> ...]<DD>
|
|
For each
|
|
<I>name</I>,
|
|
|
|
remove the corresponding variable or function.
|
|
If the
|
|
<B>-v</B>
|
|
|
|
option is given, each
|
|
<I>name</I>
|
|
|
|
refers to a shell variable, and that variable is removed.
|
|
Read-only variables may not be unset.
|
|
If
|
|
<B>-f</B>
|
|
|
|
is specified, each
|
|
<I>name</I>
|
|
|
|
refers to a shell function, and the function definition
|
|
is removed.
|
|
If the
|
|
<B>-n</B>
|
|
|
|
option is supplied, and <I>name</I> is a variable with the <I>nameref</I>
|
|
attribute, <I>name</I> will be unset rather than the variable it
|
|
references.
|
|
<B>-n</B> has no effect if the <B>-f</B> option is supplied.
|
|
If no options are supplied, each <I>name</I> refers to a variable; if
|
|
there is no variable by that name, a function with that name, if any, is
|
|
unset.
|
|
Each unset variable or function is removed from the environment
|
|
passed to subsequent commands.
|
|
If any of
|
|
<FONT SIZE=-1><B>BASH_ALIASES</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>BASH_ARGV0</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>BASH_CMDS</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>BASH_COMMAND</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>BASH_SUBSHELL</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>BASHPID</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>COMP_WORDBREAKS</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>DIRSTACK</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>EPOCHREALTIME</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>EPOCHSECONDS</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>FUNCNAME</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>GROUPS</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>HISTCMD</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>LINENO</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>RANDOM</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>SECONDS</B>,
|
|
|
|
</FONT>
|
|
or
|
|
<FONT SIZE=-1><B>SRANDOM</B>
|
|
|
|
</FONT>
|
|
are unset, they lose their special properties, even if they are
|
|
subsequently reset. The exit status is true unless a
|
|
<I>name</I>
|
|
|
|
is readonly or may not be unset.
|
|
<DT><B>wait</B> [<B>-fn</B>] [-p <I>varname</I>] [<I>id ...</I>]<DD>
|
|
Wait for each specified child process and return its termination status.
|
|
Each
|
|
<I>id</I>
|
|
|
|
may be a process
|
|
ID or a job specification; if a job spec is given, all processes
|
|
in that job's pipeline are waited for. If
|
|
<I>id</I>
|
|
|
|
is not given,
|
|
<B>wait</B> waits for all running background jobs and
|
|
the last-executed process substitution, if its process id is the same as
|
|
<B>$!</B>,
|
|
and the return status is zero.
|
|
If the <B>-n</B> option is supplied,
|
|
<B>wait</B> waits for a single job
|
|
from the list of <I>id</I>s or, if no <I>id</I>s are supplied, any job,
|
|
to complete and returns its exit status.
|
|
If none of the supplied arguments is a child of the shell, or if no arguments
|
|
are supplied and the shell has no unwaited-for children, the exit status
|
|
is 127.
|
|
If the <B>-p</B> option is supplied, the process or job identifier of the job
|
|
for which the exit status is returned is assigned to the variable
|
|
<I>varname</I> named by the option argument.
|
|
The variable will be unset initially, before any assignment.
|
|
This is useful only when the <B>-n</B> option is supplied.
|
|
Supplying the <B>-f</B> option, when job control is enabled,
|
|
forces <B>wait</B> to wait for <I>id</I> to terminate before returning
|
|
its status, instead of returning when it changes status.
|
|
If
|
|
<I>id</I>
|
|
|
|
specifies a non-existent process or job, the return status is 127.
|
|
If <B>wait</B> is interrupted by a signal, the return status will be greater
|
|
than 128, as described under
|
|
<B>SIGNALS</B>
|
|
|
|
|
|
above.
|
|
Otherwise, the return status is the exit status of the last
|
|
process or job waited for.
|
|
</DL>
|
|
<A NAME="lbDC"> </A>
|
|
<H3>SHELL COMPATIBILITY MODE</H3>
|
|
|
|
Bash-4.0 introduced the concept of a <I>shell compatibility level</I>,
|
|
specified as a set of options to the shopt builtin (
|
|
<B>compat31</B>,
|
|
|
|
<B>compat32</B>,
|
|
|
|
<B>compat40</B>,
|
|
|
|
<B>compat41</B>,
|
|
|
|
and so on).
|
|
There is only one current
|
|
compatibility level -- each option is mutually exclusive.
|
|
The compatibility level is intended to allow users to select behavior
|
|
from previous versions that is incompatible with newer versions
|
|
while they migrate scripts to use current features and
|
|
behavior. It's intended to be a temporary solution.
|
|
<P>
|
|
|
|
This section does not mention behavior that is standard for a particular
|
|
version (e.g., setting <B>compat32</B> means that quoting the rhs of the regexp
|
|
matching operator quotes special regexp characters in the word, which is
|
|
default behavior in bash-3.2 and subsequent versions).
|
|
<P>
|
|
|
|
If a user enables, say, <B>compat32</B>, it may affect the behavior of other
|
|
compatibility levels up to and including the current compatibility level.
|
|
The idea is that each compatibility level controls behavior that changed
|
|
in that version of <B>bash</B>,
|
|
but that behavior may have been present in earlier versions.
|
|
For instance, the change to use locale-based comparisons with the <B>[[</B>
|
|
command came in bash-4.1, and earlier versions used ASCII-based comparisons,
|
|
so enabling <B>compat32</B> will enable ASCII-based comparisons as well.
|
|
That granularity may not be sufficient for
|
|
all uses, and as a result users should employ compatibility levels carefully.
|
|
Read the documentation for a particular feature to find out the
|
|
current behavior.
|
|
<P>
|
|
|
|
Bash-4.3 introduced a new shell variable:
|
|
<FONT SIZE=-1><B>BASH_COMPAT</B>.
|
|
|
|
</FONT>
|
|
The value assigned
|
|
to this variable (a decimal version number like 4.2, or an integer
|
|
corresponding to the <B>compat</B><I>NN</I> option, like 42) determines the
|
|
compatibility level.
|
|
<P>
|
|
|
|
Starting with bash-4.4, Bash has begun deprecating older compatibility
|
|
levels.
|
|
Eventually, the options will be removed in favor of
|
|
<FONT SIZE=-1><B>BASH_COMPAT</B>.
|
|
|
|
</FONT>
|
|
<P>
|
|
|
|
Bash-5.0 is the final version for which there will be an individual shopt
|
|
option for the previous version. Users should use
|
|
<FONT SIZE=-1><B>BASH_COMPAT</B>
|
|
|
|
</FONT>
|
|
on bash-5.0 and later versions.
|
|
<P>
|
|
|
|
The following table describes the behavior changes controlled by each
|
|
compatibility level setting.
|
|
The <B>compat</B><I>NN</I> tag is used as shorthand for setting the
|
|
compatibility level
|
|
to <I>NN</I> using one of the following mechanisms.
|
|
For versions prior to bash-5.0, the compatibility level may be set using
|
|
the corresponding <B>compat</B><I>NN</I> shopt option.
|
|
For bash-4.3 and later versions, the
|
|
<FONT SIZE=-1><B>BASH_COMPAT</B>
|
|
|
|
</FONT>
|
|
variable is preferred,
|
|
and it is required for bash-5.1 and later versions.
|
|
<DL COMPACT>
|
|
<DT><B>compat31</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
quoting the rhs of the <B>[[</B> command's regexp matching operator (=~)
|
|
has no special effect
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat32</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
interrupting a command list such as "a ; b ; c" causes the execution
|
|
of the next command in the list (in bash-4.0 and later versions,
|
|
the shell acts as if it received the interrupt, so
|
|
interrupting one command in a list aborts the execution of the
|
|
entire list)
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat40</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
the <B><</B> and <B>></B> operators to the <B>[[</B> command do not
|
|
consider the current locale when comparing strings; they use ASCII
|
|
ordering.
|
|
Bash versions prior to bash-4.1 use ASCII collation and
|
|
<I>strcmp</I>(3);
|
|
|
|
bash-4.1 and later use the current locale's collation sequence and
|
|
<I>strcoll</I>(3).
|
|
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat41</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
in <I>posix</I> mode, <B>time</B> may be followed by options and still be
|
|
recognized as a reserved word (this is POSIX interpretation 267)
|
|
<DT>*<DD>
|
|
in <I>posix</I> mode, the parser requires that an even number of single
|
|
quotes occur in the <I>word</I> portion of a double-quoted
|
|
parameter expansion and treats them specially, so that characters within
|
|
the single quotes are considered quoted
|
|
(this is POSIX interpretation 221)
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat42</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
the replacement string in double-quoted pattern substitution does not
|
|
undergo quote removal, as it does in versions after bash-4.2
|
|
<DT>*<DD>
|
|
in posix mode, single quotes are considered special when expanding
|
|
the <I>word</I> portion of a double-quoted parameter expansion
|
|
and can be used to quote a closing brace or other special character
|
|
(this is part of POSIX interpretation 221);
|
|
in later versions, single quotes
|
|
are not special within double-quoted word expansions
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat43</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
the shell does not print a warning message if an attempt is made to
|
|
use a quoted compound assignment as an argument to declare
|
|
(e.g., declare -a foo=aq(1 2)aq). Later versions warn that this usage is
|
|
deprecated
|
|
<DT>*<DD>
|
|
word expansion errors are considered non-fatal errors that cause the
|
|
current command to fail, even in posix mode
|
|
(the default behavior is to make them fatal errors that cause the shell
|
|
to exit)
|
|
<DT>*<DD>
|
|
when executing a shell function, the loop state (while/until/etc.)
|
|
is not reset, so <B>break</B> or <B>continue</B> in that function will break
|
|
or continue loops in the calling context. Bash-4.4 and later reset
|
|
the loop state to prevent this
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat44</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
the shell sets up the values used by
|
|
<FONT SIZE=-1><B>BASH_ARGV</B>
|
|
|
|
</FONT>
|
|
and
|
|
<FONT SIZE=-1><B>BASH_ARGC</B>
|
|
|
|
</FONT>
|
|
so they can expand to the shell's positional parameters even if extended
|
|
debugging mode is not enabled
|
|
<DT>*<DD>
|
|
a subshell inherits loops from its parent context, so <B>break</B>
|
|
or <B>continue</B> will cause the subshell to exit.
|
|
Bash-5.0 and later reset the loop state to prevent the exit
|
|
<DT>*<DD>
|
|
variable assignments preceding builtins like <B>export</B> and <B>readonly</B>
|
|
that set attributes continue to affect variables with the same
|
|
name in the calling environment even if the shell is not in posix
|
|
mode
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat50</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
Bash-5.1 changed the way
|
|
<FONT SIZE=-1><B>$RANDOM</B>
|
|
|
|
</FONT>
|
|
is generated to introduce slightly
|
|
more randomness. If the shell compatibility level is set to 50 or
|
|
lower, it reverts to the method from bash-5.0 and previous versions,
|
|
so seeding the random number generator by assigning a value to
|
|
<FONT SIZE=-1><B>RANDOM</B>
|
|
|
|
</FONT>
|
|
will produce the same sequence as in bash-5.0
|
|
<DT>*<DD>
|
|
If the command hash table is empty, bash versions prior to bash-5.1
|
|
printed an informational message to that effect, even when producing
|
|
output that can be reused as input. Bash-5.1 suppresses that message
|
|
when the <B>-l</B> option is supplied.
|
|
</DL></DL>
|
|
|
|
|
|
<DT><B>compat51</B><DD>
|
|
|
|
<DL COMPACT><DT><DD>
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
The <B>unset</B> builtin treats attempts to unset array subscripts <B>@</B>
|
|
and <B>*</B> differently depending on whether the array is indexed or
|
|
associative, and differently than in previous versions.
|
|
</DL></DL>
|
|
|
|
|
|
|
|
|
|
</DL>
|
|
<A NAME="lbDD"> </A>
|
|
<H3>RESTRICTED SHELL</H3>
|
|
|
|
|
|
|
|
<P>
|
|
|
|
If
|
|
<B>bash</B>
|
|
|
|
is started with the name
|
|
<B>rbash</B>,
|
|
|
|
or the
|
|
<B>-r</B>
|
|
|
|
option is supplied at invocation,
|
|
the shell becomes restricted.
|
|
A restricted shell is used to
|
|
set up an environment more controlled than the standard shell.
|
|
It behaves identically to
|
|
<B>bash</B>
|
|
|
|
with the exception that the following are disallowed or not performed:
|
|
<DL COMPACT>
|
|
<DT>*<DD>
|
|
changing directories with <B>cd</B>
|
|
<DT>*<DD>
|
|
setting or unsetting the values of
|
|
<FONT SIZE=-1><B>SHELL</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>PATH</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>HISTFILE</B>,
|
|
|
|
</FONT>
|
|
<FONT SIZE=-1><B>ENV</B>,
|
|
|
|
</FONT>
|
|
or
|
|
<FONT SIZE=-1><B>BASH_ENV</B>
|
|
|
|
</FONT>
|
|
<DT>*<DD>
|
|
specifying command names containing
|
|
<B>/</B>
|
|
|
|
<DT>*<DD>
|
|
specifying a filename containing a
|
|
<B>/</B>
|
|
|
|
as an argument to the
|
|
<B>.</B>
|
|
|
|
builtin command
|
|
<DT>*<DD>
|
|
specifying a filename containing a slash as an argument to the
|
|
<B>history</B>
|
|
|
|
builtin command
|
|
<DT>*<DD>
|
|
specifying a filename containing a slash as an argument to the
|
|
<B>-p</B>
|
|
|
|
option to the
|
|
<B>hash</B>
|
|
|
|
builtin command
|
|
<DT>*<DD>
|
|
importing function definitions from the shell environment at startup
|
|
<DT>*<DD>
|
|
parsing the value of
|
|
<FONT SIZE=-1><B>SHELLOPTS</B>
|
|
|
|
</FONT>
|
|
from the shell environment at startup
|
|
<DT>*<DD>
|
|
redirecting output using the >, >|, <>, >&, &>, and >> redirection operators
|
|
<DT>*<DD>
|
|
using the
|
|
<B>exec</B>
|
|
|
|
builtin command to replace the shell with another command
|
|
<DT>*<DD>
|
|
adding or deleting builtin commands with the
|
|
<B>-f</B>
|
|
|
|
and
|
|
<B>-d</B>
|
|
|
|
options to the
|
|
<B>enable</B>
|
|
|
|
builtin command
|
|
<DT>*<DD>
|
|
using the <B>enable</B> builtin command to enable disabled shell builtins
|
|
<DT>*<DD>
|
|
specifying the
|
|
<B>-p</B>
|
|
|
|
option to the
|
|
<B>command</B>
|
|
|
|
builtin command
|
|
<DT>*<DD>
|
|
turning off restricted mode with
|
|
<B>set +r</B> or <B>shopt -u restricted_shell</B>.
|
|
</DL>
|
|
<P>
|
|
|
|
These restrictions are enforced after any startup files are read.
|
|
<P>
|
|
|
|
|
|
When a command that is found to be a shell script is executed
|
|
(see
|
|
<FONT SIZE=-1><B>COMMAND EXECUTION</B>
|
|
|
|
</FONT>
|
|
|
|
above),
|
|
|
|
<B>rbash</B>
|
|
|
|
turns off any restrictions in the shell spawned to execute the
|
|
script.
|
|
|
|
|
|
<A NAME="lbDE"> </A>
|
|
<H3>SEE ALSO</H3>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT><I>Bash Reference Manual</I>, Brian Fox and Chet Ramey<DD>
|
|
<DT><I>The Gnu Readline Library</I>, Brian Fox and Chet Ramey<DD>
|
|
<DT><I>The Gnu History Library</I>, Brian Fox and Chet Ramey<DD>
|
|
<DT><I>Portable Operating System Interface (POSIX) Part 2: Shell and Utilities</I>, IEEE --<DD>
|
|
<A HREF="http://pubs.opengroup.org/onlinepubs/9699919799/">http://pubs.opengroup.org/onlinepubs/9699919799/</A>
|
|
<DT><A HREF="http://tiswww.case.edu/~chet/bash/POSIX">http://tiswww.case.edu/~chet/bash/POSIX</A> -- a description of posix mode<DD>
|
|
<DT><I>sh</I>(1), <I>ksh</I>(1), <I>csh</I>(1)<DD>
|
|
<DT><I>emacs</I>(1), <I>vi</I>(1)<DD>
|
|
<DT><I>readline</I>(3)<DD>
|
|
|
|
</DL>
|
|
<A NAME="lbDF"> </A>
|
|
<H3>FILES</H3>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT>
|
|
<A HREF="file:/bin/bash"><I>/bin/bash</I></A>
|
|
|
|
<DD>
|
|
The <B>bash</B> executable
|
|
<DT>
|
|
<A HREF="file:/etc/profile"><I>/etc/profile</I></A>
|
|
|
|
<DD>
|
|
The systemwide initialization file, executed for login shells
|
|
<DT>
|
|
<A HREF="file:~/.bash_profile"><I>~/.bash_profile</I></A>
|
|
|
|
<DD>
|
|
The personal initialization file, executed for login shells
|
|
<DT>
|
|
<A HREF="file:~/.bashrc"><I>~/.bashrc</I></A>
|
|
|
|
<DD>
|
|
The individual per-interactive-shell startup file
|
|
<DT>
|
|
<A HREF="file:~/.bash_logout"><I>~/.bash_logout</I></A>
|
|
|
|
<DD>
|
|
The individual login shell cleanup file, executed when a login shell exits
|
|
<DT>
|
|
<A HREF="file:~/.bash_history"><I>~/.bash_history</I></A>
|
|
|
|
<DD>
|
|
The default value of <B>HISTFILE</B>, the file in which bash saves the
|
|
command history
|
|
<DT>
|
|
<A HREF="file:~/.inputrc"><I>~/.inputrc</I></A>
|
|
|
|
<DD>
|
|
Individual <I>readline</I> initialization file
|
|
|
|
</DL>
|
|
<A NAME="lbDG"> </A>
|
|
<H3>AUTHORS</H3>
|
|
|
|
Brian Fox, Free Software Foundation
|
|
<BR>
|
|
|
|
<A HREF="mailto:bfox@gnu.org">bfox@gnu.org</A>
|
|
<P>
|
|
|
|
Chet Ramey, Case Western Reserve University
|
|
<BR>
|
|
|
|
<A HREF="mailto:chet.ramey@case.edu">chet.ramey@case.edu</A>
|
|
<A NAME="lbDH"> </A>
|
|
<H3>BUG REPORTS</H3>
|
|
|
|
If you find a bug in
|
|
<B>bash,</B>
|
|
|
|
you should report it. But first, you should
|
|
make sure that it really is a bug, and that it appears in the latest
|
|
version of
|
|
<B>bash</B>.
|
|
|
|
The latest version is always available from
|
|
<I><A HREF="ftp://ftp.gnu.org/pub/gnu/bash/">ftp://ftp.gnu.org/pub/gnu/bash/</A></I> and
|
|
<I><A HREF="http://git.savannah.gnu.org/cgit/bash.git/snapshot/bash-master.tar.gz">http://git.savannah.gnu.org/cgit/bash.git/snapshot/bash-master.tar.gz</A></I>.
|
|
<P>
|
|
|
|
Once you have determined that a bug actually exists, use the
|
|
<I>bashbug</I>
|
|
|
|
command to submit a bug report.
|
|
If you have a fix, you are encouraged to mail that as well!
|
|
Suggestions and `philosophical' bug reports may be mailed
|
|
to <I><A HREF="mailto:bug-bash@gnu.org">bug-bash@gnu.org</A></I> or posted to the Usenet
|
|
newsgroup
|
|
<A HREF="news:gnu.bash.bug">gnu.bash.bug</A>.
|
|
|
|
<P>
|
|
|
|
ALL bug reports should include:
|
|
<P>
|
|
|
|
|
|
<DL COMPACT>
|
|
<DT>The version number of <B>bash</B><DD>
|
|
<DT>The hardware and operating system<DD>
|
|
<DT>The compiler used to compile<DD>
|
|
<DT>A description of the bug behaviour<DD>
|
|
<DT>A short script or `recipe' which exercises the bug<DD>
|
|
|
|
</DL>
|
|
<P>
|
|
|
|
<I>bashbug</I>
|
|
|
|
inserts the first three items automatically into the template
|
|
it provides for filing a bug report.
|
|
<P>
|
|
|
|
Comments and bug reports concerning
|
|
this manual page should be directed to
|
|
<I><A HREF="mailto:chet.ramey@case.edu">chet.ramey@case.edu</A></I>.
|
|
|
|
<A NAME="lbDI"> </A>
|
|
<H3>BUGS</H3>
|
|
|
|
It's too big and too slow.
|
|
<P>
|
|
|
|
There are some subtle differences between
|
|
<B>bash</B>
|
|
|
|
and traditional versions of
|
|
<B>sh</B>,
|
|
|
|
mostly because of the
|
|
<FONT SIZE=-1><B>POSIX</B>
|
|
|
|
</FONT>
|
|
specification.
|
|
<P>
|
|
|
|
Aliases are confusing in some uses.
|
|
<P>
|
|
|
|
Shell builtin commands and functions are not stoppable/restartable.
|
|
<P>
|
|
|
|
Compound commands and command sequences of the form `a ; b ; c'
|
|
are not handled gracefully when process suspension is attempted.
|
|
When a process is stopped, the shell immediately executes the next
|
|
command in the sequence.
|
|
It suffices to place the sequence of commands between
|
|
parentheses to force it into a subshell, which may be stopped as
|
|
a unit.
|
|
<P>
|
|
|
|
Array variables may not (yet) be exported.
|
|
<P>
|
|
|
|
There may be only one active coprocess at a time.
|
|
|
|
|
|
|
|
<HR>
|
|
<TABLE WIDTH=100%>
|
|
<TR>
|
|
<TH ALIGN=LEFT width=33%>GNU Bash 5.2<TH ALIGN=CENTER width=33%>2022 September 19<TH ALIGN=RIGHT width=33%>BASH(1)
|
|
</TR>
|
|
</TABLE>
|
|
<HR>
|
|
<A NAME="index"> </A><H2>Index</H2>
|
|
<DL>
|
|
<DT><A HREF="#lbAB">NAME</A><DD>
|
|
<DT><A HREF="#lbAC">SYNOPSIS</A><DD>
|
|
<DT><A HREF="#lbAD">COPYRIGHT</A><DD>
|
|
<DT><A HREF="#lbAE">DESCRIPTION</A><DD>
|
|
<DT><A HREF="#lbAF">OPTIONS</A><DD>
|
|
<DT><A HREF="#lbAG">ARGUMENTS</A><DD>
|
|
<DT><A HREF="#lbAH">INVOCATION</A><DD>
|
|
<DT><A HREF="#lbAI">DEFINITIONS</A><DD>
|
|
<DT><A HREF="#lbAJ">RESERVED WORDS</A><DD>
|
|
<DT><A HREF="#lbAK">SHELL GRAMMAR</A><DD>
|
|
<DL>
|
|
<DT><A HREF="#lbAL">Simple Commands</A><DD>
|
|
<DT><A HREF="#lbAM">Pipelines</A><DD>
|
|
<DT><A HREF="#lbAN">Lists</A><DD>
|
|
<DT><A HREF="#lbAO">Compound Commands</A><DD>
|
|
<DT><A HREF="#lbAP">Coprocesses</A><DD>
|
|
<DT><A HREF="#lbAQ">Shell Function Definitions</A><DD>
|
|
</DL>
|
|
<DT><A HREF="#lbAR">COMMENTS</A><DD>
|
|
<DT><A HREF="#lbAS">QUOTING</A><DD>
|
|
<DT><A HREF="#lbAT">PARAMETERS</A><DD>
|
|
<DL>
|
|
<DT><A HREF="#lbAU">Positional Parameters</A><DD>
|
|
<DT><A HREF="#lbAV">Special Parameters</A><DD>
|
|
<DT><A HREF="#lbAW">Shell Variables</A><DD>
|
|
<DT><A HREF="#lbAX">Arrays</A><DD>
|
|
</DL>
|
|
<DT><A HREF="#lbAY">EXPANSION</A><DD>
|
|
<DL>
|
|
<DT><A HREF="#lbAZ">Brace Expansion</A><DD>
|
|
<DT><A HREF="#lbBA">Tilde Expansion</A><DD>
|
|
<DT><A HREF="#lbBB">Parameter Expansion</A><DD>
|
|
<DT><A HREF="#lbBC">Command Substitution</A><DD>
|
|
<DT><A HREF="#lbBD">Arithmetic Expansion</A><DD>
|
|
<DT><A HREF="#lbBE">Process Substitution</A><DD>
|
|
<DT><A HREF="#lbBF">Word Splitting</A><DD>
|
|
<DT><A HREF="#lbBG">Pathname Expansion</A><DD>
|
|
<DT><A HREF="#lbBH">Quote Removal</A><DD>
|
|
</DL>
|
|
<DT><A HREF="#lbBI">REDIRECTION</A><DD>
|
|
<DL>
|
|
<DT><A HREF="#lbBJ">Redirecting Input</A><DD>
|
|
<DT><A HREF="#lbBK">Redirecting Output</A><DD>
|
|
<DT><A HREF="#lbBL">Appending Redirected Output</A><DD>
|
|
<DT><A HREF="#lbBM">Redirecting Standard Output and Standard Error</A><DD>
|
|
<DT><A HREF="#lbBN">Appending Standard Output and Standard Error</A><DD>
|
|
<DT><A HREF="#lbBO">Here Documents</A><DD>
|
|
<DT><A HREF="#lbBP">Here Strings</A><DD>
|
|
<DT><A HREF="#lbBQ">Duplicating File Descriptors</A><DD>
|
|
<DT><A HREF="#lbBR">Moving File Descriptors</A><DD>
|
|
<DT><A HREF="#lbBS">Opening File Descriptors for Reading and Writing</A><DD>
|
|
</DL>
|
|
<DT><A HREF="#lbBT">ALIASES</A><DD>
|
|
<DT><A HREF="#lbBU">FUNCTIONS</A><DD>
|
|
<DT><A HREF="#lbBV">ARITHMETIC EVALUATION</A><DD>
|
|
<DT><A HREF="#lbBW">CONDITIONAL EXPRESSIONS</A><DD>
|
|
<DT><A HREF="#lbBX">SIMPLE COMMAND EXPANSION</A><DD>
|
|
<DT><A HREF="#lbBY">COMMAND EXECUTION</A><DD>
|
|
<DT><A HREF="#lbBZ">COMMAND EXECUTION ENVIRONMENT</A><DD>
|
|
<DT><A HREF="#lbCA">ENVIRONMENT</A><DD>
|
|
<DT><A HREF="#lbCB">EXIT STATUS</A><DD>
|
|
<DT><A HREF="#lbCC">SIGNALS</A><DD>
|
|
<DT><A HREF="#lbCD">JOB CONTROL</A><DD>
|
|
<DT><A HREF="#lbCE">PROMPTING</A><DD>
|
|
<DT><A HREF="#lbCF">READLINE</A><DD>
|
|
<DL>
|
|
<DT><A HREF="#lbCG">Readline Notation</A><DD>
|
|
<DT><A HREF="#lbCH">Readline Initialization</A><DD>
|
|
<DT><A HREF="#lbCI">Readline Key Bindings</A><DD>
|
|
<DT><A HREF="#lbCJ">Readline Variables</A><DD>
|
|
<DT><A HREF="#lbCK">Readline Conditional Constructs</A><DD>
|
|
<DT><A HREF="#lbCL">Searching</A><DD>
|
|
<DT><A HREF="#lbCM">Readline Command Names</A><DD>
|
|
<DT><A HREF="#lbCN">Commands for Moving</A><DD>
|
|
<DT><A HREF="#lbCO">Commands for Manipulating the History</A><DD>
|
|
<DT><A HREF="#lbCP">Commands for Changing Text</A><DD>
|
|
<DT><A HREF="#lbCQ">Killing and Yanking</A><DD>
|
|
<DT><A HREF="#lbCR">Numeric Arguments</A><DD>
|
|
<DT><A HREF="#lbCS">Completing</A><DD>
|
|
<DT><A HREF="#lbCT">Keyboard Macros</A><DD>
|
|
<DT><A HREF="#lbCU">Miscellaneous</A><DD>
|
|
<DT><A HREF="#lbCV">Programmable Completion</A><DD>
|
|
</DL>
|
|
<DT><A HREF="#lbCW">HISTORY</A><DD>
|
|
<DT><A HREF="#lbCX">HISTORY EXPANSION</A><DD>
|
|
<DL>
|
|
<DT><A HREF="#lbCY">Event Designators</A><DD>
|
|
<DT><A HREF="#lbCZ">Word Designators</A><DD>
|
|
<DT><A HREF="#lbDA">Modifiers</A><DD>
|
|
</DL>
|
|
<DT><A HREF="#lbDB">SHELL BUILTIN COMMANDS</A><DD>
|
|
<DT><A HREF="#lbDC">SHELL COMPATIBILITY MODE</A><DD>
|
|
<DT><A HREF="#lbDD">RESTRICTED SHELL</A><DD>
|
|
<DT><A HREF="#lbDE">SEE ALSO</A><DD>
|
|
<DT><A HREF="#lbDF">FILES</A><DD>
|
|
<DT><A HREF="#lbDG">AUTHORS</A><DD>
|
|
<DT><A HREF="#lbDH">BUG REPORTS</A><DD>
|
|
<DT><A HREF="#lbDI">BUGS</A><DD>
|
|
</DL>
|
|
<HR>
|
|
This document was created by man2html from /usr/local/src/bash/bash-20220907/doc/bash.1.<BR>
|
|
Time: 19 September 2022 12:02:51 EDT
|
|
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|
|
</HTML>
|