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This is a terse description of the new features added to bash-5.2 since
the release of bash-5.1. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. The bash malloc returns memory that is aligned on 16-byte boundaries.
b. There is a new internal timer framework used for read builtin timeouts.
c. Rewrote the command substitution parsing code to call the parser recursively
and rebuild the command string from the parsed command. This allows better
syntax checking and catches errors much earlier. Along with this, if
command substitution parsing completes with here-documents remaining to be
read, the shell prints a warning message and reads the here-document bodies
from the current input stream.
d. The `ulimit' builtin now treats an operand remaining after all of the options
and arguments are parsed as an argument to the last command specified by
an option. This is for POSIX compatibility.
e. Here-document parsing now handles $'...' and $"..." quoting when reading the
here-document body.
f. The `shell-expand-line' and `history-and-alias-expand-line' bindable readline
commands now understand $'...' and $"..." quoting.
g. There is a new `spell-correct-word' bindable readline command to perform
spelling correction on the current word.
h. The `unset' builtin now attempts to treat arguments as array subscripts
without parsing or expanding the subscript, even when `assoc_expand_once'
is not set.
i. There is a default value for $BASH_LOADABLES_PATH in config-top.h.
j. Associative array assignment and certain instances of referencing (e.g.,
`test -v' now allow `@' and `*' to be used as keys.
k. Bash attempts to expand indexed array subscripts only once when executing
shell constructs and word expansions.
l. The `unset' builtin allows a subscript of `@' or `*' to unset a key with
that value for associative arrays instead of unsetting the entire array
(which you can still do with `unset arrayname'). For indexed arrays, it
removes all elements of the array without unsetting it (like `A=()').
m. Additional builtins (printf/test/read/wait) do a better job of not
parsing array subscripts if array_expand_once is set.
n. New READLINE_ARGUMENT variable set to numeric argument for readline commands
defined using `bind -x'.
o. The new `varredir_close' shell option causes bash to automatically close
file descriptors opened with {var}<fn and other styles of varassign
redirection unless they're arguments to the `exec' builtin.
p. The `$0' special parameter is now set to the name of the script when running
any (non-interactive) startup files such as $BASH_ENV.
q. The `enable' builtin tries to load a loadable builtin using the default
search path if `enable name' (without any options) attempts to enable a
non-existent builtin.
r. The `printf' builtin has a new format specifier: %Q. This acts like %q but
applies any specified precision to the original unquoted argument, then
quotes and outputs the result.
s. The new `noexpand_translations' option controls whether or not the translated
output of $"..." is single-quoted.
t. There is a new parameter transformation operator: @k. This is like @K, but
expands the result to separate words after word splitting.
u. There is an alternate array implementation, selectable at `configure' time,
that optimizes access speed over memory use (use the new configure
--enable-alt-array-implementation option).
v. If an [N]<&WORD- or [N]>&WORD- redirection has WORD expand to the empty
string, treat the redirection as [N]<&- or [N]>&- and close file descriptor
N (default 0).
w. Invalid parameter transformation operators are now invalid word expansions,
and so cause fatal errors in non-interactive shells.
x. New shell option: patsub_replacement. When enabled, a `&' in the replacement
string of the pattern substitution expansion is replaced by the portion of
the string that matched the pattern. Backslash will escape the `&' and
insert a literal `&'.
y. `command -p' no longer looks in the hash table for the specified command.
z. The new `--enable-translatable-strings' option to `configure' allows $"..."
support to be compiled in or out.
aa. The new `globskipdots' shell option forces pathname expansion never to
return `.' or `..' unless explicitly matched. It is enabled by default.
bb. Array references using `@' and `*' that are the value of nameref variables
(declare -n ref='v[@]' ; echo $ref) no longer cause the shell to exit if
set -u is enabled and the array (v) is unset.
cc. There is a new bindable readline command name:
`vi-edit-and-execute-command'.
dd. In posix mode, the `printf' builtin checks for the `L' length modifier and
uses long double for floating point conversion specifiers if it's present,
double otherwise.
ee. The `globbing' completion code now takes the `globstar' option into account.
ff. `suspend -f' now forces the shell to suspend even if job control is not
currently enabled.
gg. Since there is no `declare -' equivalent of `local -', make sure to use
`local -' in the output of `local -p'.
2. New Features in Readline
a. There is now an HS_HISTORY_VERSION containing the version number of the
history library for applications to use.
b. History expansion better understands multiple history expansions that may
contain strings that would ordinarily inhibit history expansion (e.g.,
`abc!$!$').
c. There is a new framework for readline timeouts, including new public
functions to set timeouts and query how much time is remaining before a
timeout hits, and a hook function that can trigger when readline times
out. There is a new state value to indicate a timeout.
d. Automatically bind termcap key sequences for page-up and page-down to
history-search-backward and history-search-forward, respectively.
e. There is a new `fetch-history' bindable command that retrieves the history
entry corresponding to its numeric argument. Negative arguments count back
from the end of the history.
f. `vi-undo' is now a bindable command.
g. There is a new option: `enable-active-region'. This separates control of
the active region and bracketed-paste. It has the same default value as
bracketed-paste, and enabling bracketed paste enables the active region.
Users can now turn off the active region while leaving bracketed paste
enabled.
h. rl_completer_word_break_characters is now `const char *' like
rl_basic_word_break_characters.
i. Readline looks in $LS_COLORS for a custom filename extension
(*.readline-colored-completion-prefix) and uses that as the default color
for the common prefix displayed when `colored-completion-prefix' is set.
j. Two new bindable string variables: active-region-start-color and
active-region-end-color. The first sets the color used to display the
active region; the second turns it off. If set, these are used in place
of terminal standout mode.
k. New readline state (RL_STATE_EOF) and application-visible variable
(rl_eof_found) to allow applications to detect when readline reads EOF
before calling the deprep-terminal hook.
l. There is a new configuration option: --with-shared-termcap-library, which
forces linking the shared readline library with the shared termcap (or
curses/ncurses/termlib) library so applications don't have to do it.
m. Readline now checks for changes to locale settings (LC_ALL/LC_CTYPE/LANG)
each time it is called, and modifies the appropriate locale-specific display
and key binding variables when the locale changes.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-5.1 since
the release of bash-5.0. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. `bind -x' now supports different bindings for different editing modes and
keymaps.
b. Bash attempts to optimize the number of times it forks when executing
commands in subshells and from `bash -c'.
c. Here documents and here strings now use pipes for the expanded document if
it's smaller than the pipe buffer size, reverting to temporary files if it's
larger.
d. There are new loadable builtins: mktemp, accept, mkfifo, csv, cut/lcut
e. In posix mode, `trap -p' now displays signals whose disposition is SIG_DFL
and those that were SIG_IGN when the shell starts.
f. The shell now expands the history number (e.g., in PS1) even if it is not
currently saving commands to the history list.
g. `read -e' may now be used with arbitrary file descriptors (`read -u N').
h. The `select' builtin now runs traps if its internal call to the read builtin
is interrupted by a signal.
i. SRANDOM: a new variable that expands to a 32-bit random number that is not
produced by an LCRNG, and uses getrandom/getentropy, falling back to
/dev/urandom or arc4random if available. There is a fallback generator if
none of these are available.
j. shell-transpose-words: a new bindable readline command that uses the same
definition of word as shell-forward-word, etc.
k. The shell now adds default bindings for shell-forward-word,
shell-backward-word, shell-transpose-words, and shell-kill-word.
l. Bash now allows ARGV0 appearing in the initial shell environment to set $0.
m. If `unset' is executed without option arguments, bash tries to unset a shell
function if a name argument cannot be a shell variable name because it's not
an identifier.
n. The `test -N' operator uses nanosecond timestamp granularity if it's
available.
o. Bash posix mode now treats assignment statements preceding shell function
definitions the same as in its default mode, since POSIX has changed and
no longer requires those assignments to persist after the function returns
(POSIX interp 654).
p. BASH_REMATCH is no longer readonly.
q. wait: has a new -p VARNAME option, which stores the PID returned by `wait -n'
or `wait' without arguments.
r. Sorting the results of pathname expansion now uses byte-by-byte comparisons
if two strings collate equally to impose a total order; the result of a
POSIX interpretation.
s. Bash now allows SIGINT trap handlers to execute recursively.
t. Bash now saves and restores state around setting and unsetting posix mode,
instead of having unsetting posix mode set a known state.
u. Process substitution is now available in posix mode.
v. READLINE_MARK: a new variable available while executing commands bound with
`bind -x', contains the value of the mark.
w. Bash removes SIGCHLD from the set of blocked signals if it's blocked at shell
startup.
x. `test -v N' can now test whether or not positional parameter N is set.
y. `local' now honors the `-p' option to display all local variables at the
current context.
z. The `@a' variable transformation now prints attributes for unset array
variables.
aa. The `@A' variable transformation now prints a declare command that sets a
variable's attributes if the variable has attributes but is unset.
bb. `declare' and `local' now have a -I option that inherits attributes and
value from a variable with the same name at a previous scope.
cc. When run from a -c command, `jobs' now reports the status of completed jobs.
dd. New `U', `u', and `L' parameter transformations to convert to uppercase,
convert first character to uppercase, and convert to lowercase,
respectively.
ee. PROMPT_COMMAND: can now be an array variable, each element of which can
contain a command to be executed like a string PROMPT_COMMAND variable.
ff. `ulimit' has a -R option to report and set the RLIMIT_RTTIME resource.
gg. Associative arrays may be assigned using a list of key-value pairs within
a compound assignment. Compound assignments where the words are not of
the form [key]=value are assumed to be key-value assignments. A missing or
empty key is an error; a missing value is treated as NULL. Assignments may
not mix the two forms.
hh. New `K' parameter transformation to display associative arrays as key-
value pairs.
ii. Writing history to syslog now handles messages longer than the syslog max
length by writing multiple messages with a sequence number.
jj. SECONDS and RANDOM may now be assigned using arithmetic expressions, since
they are nominally integer variables. LINENO is not an integer variable.
kk. Bash temporarily suppresses the verbose option when running the DEBUG trap
while running a command from the `fc' builtin.
ll. `wait -n' now accepts a list of job specifications as arguments and will
wait for the first one in the list to change state.
mm. The associative array implementation can now dynamically increase the
size of the hash table based on insertion patterns.
nn. HISTFILE is now readonly in a restricted shell.
oo. The bash malloc now returns memory that is 16-byte aligned on 64-bit
systems.
pp. If the hash builtin is listing hashed filenames portably, don't print
anything if the table is empty.
qq. GLOBIGNORE now ignores `.' and `..' as a terminal pathname component.
rr. Bash attempts to optimize away forks in the last command in a function body
under appropriate circumstances.
ss. The globbing code now uses fnmatch(3) to check collation elements (if
available) even in cases without multibyte characters.
tt. The `fg' and `bg' builtins now return an error in a command substitution
when asked to restart a job inherited from the parent shell.
uu. The shell now attempts to unlink all FIFOs on exit, whether a consuming
process has finished with them or not.
vv. There is a new contributed loadable builtin: asort.
2. New Features in Readline
a. If a second consecutive completion attempt produces matches where the first
did not, treat it as a new completion attempt and insert a match as
appropriate.
b. Bracketed paste mode works in more places: incremental search strings, vi
overstrike mode, character search, and reading numeric arguments.
c. Readline automatically switches to horizontal scrolling if the terminal has
only one line.
d. Unbinding all key sequences bound to a particular readline function now
descends into keymaps for multi-key sequences.
e. rl-clear-display: new bindable command that clears the screen and, if
possible, the scrollback buffer (bound to emacs mode M-C-l by default).
f. New active mark and face feature: when enabled, it will highlight the text
inserted by a bracketed paste (the `active region') and the text found by
incremental and non-incremental history searches. This is tied to bracketed
paste and can be disabled by turning off bracketed paste.
g. Readline sets the mark in several additional commands.
h. Bracketed paste mode is enabled by default.
i. Readline tries to take advantage of the more regular structure of UTF-8
characters to identify the beginning and end of characters when moving
through the line buffer.
j. The bindable operate-and-get-next command (and its default bindings) are
now part of readline instead of a bash-specific addition.
k. The signal cleanup code now blocks SIGINT while processing after a SIGINT.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-5.0 since
the release of bash-4.4. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. The `wait' builtin can now wait for the last process substitution created.
b. There is an EPOCHSECONDS variable, which expands to the time in seconds
since the Unix epoch.
c. There is an EPOCHREALTIME variable, which expands to the time in seconds
since the Unix epoch with microsecond granularity.
d. New loadable builtins: rm, stat, fdflags.
e. BASH_ARGV0: a new variable that expands to $0 and sets $0 on assignment.
f. When supplied a numeric argument, the shell-expand-line bindable readline
command does not perform quote removal and suppresses command and process
substitution.
g. `history -d' understands negative arguments: negative arguments offset from
the end of the history list.
h. The `name' argument to the `coproc' reserved word now undergoes word
expansion, so unique coprocs can be created in loops.
i. A nameref name resolution loop in a function now resolves to a variable by
that name in the global scope.
j. The `wait' builtin now has a `-f' option, which signifies to wait until the
specified job or process terminates, instead of waiting until it changes
state.
k. There is a define in config-top.h that allows the shell to use a static
value for $PATH, overriding whatever is in the environment at startup, for
use by the restricted shell.
l. Process substitution does not inherit the `v' option, like command
substitution.
m. If a non-interactive shell with job control enabled detects that a foreground
job died due to SIGINT, it acts as if it received the SIGINT.
n. The SIGCHLD trap is run once for each exiting child process even if job
control is not enabled when the shell is in Posix mode.
o. A new shopt option: localvar_inherit; if set, a local variable inherits the
value of a variable with the same name at the nearest preceding scope.
p. `bind -r' now checks whether a key sequence is bound before binding it to
NULL, to avoid creating keymaps for a multi-key sequence.
q. A numeric argument to the line editing `operate-and-get-next' command
specifies which history entry to use.
r. The positional parameters are now assigned before running the shell startup
files, so startup files can use $@.
s. There is a compile-time option that forces the shell to disable the check
for an inherited OLDPWD being a directory.
t. The `history' builtin can now delete ranges of history entries using
`-d start-end'.
u. The `vi-edit-and-execute-command' bindable readline command now puts readline
back in vi insertion mode after executing commands from the edited file.
v. The command completion code now matches aliases and shell function names
case-insensitively if the readline completion-ignore-case variable is set.
w. There is a new `assoc_expand_once' shell option that attempts to expand
associative array subscripts only once.
x. The shell only sets up BASH_ARGV and BASH_ARGC at startup if extended
debugging mode is active. The old behavior of unconditionally setting them
is available as part of the shell compatibility options.
y. The `umask' builtin now allows modes and masks greater than octal 777.
z. The `times' builtin now honors the current locale when printing a decimal
point.
aa. There is a new (disabled by default, undocumented) shell option to enable
and disable sending history to syslog at runtime.
bb. Bash no longer allows variable assignments preceding a special builtin that
changes variable attributes to propagate back to the calling environment
unless the compatibility level is 44 or lower.
cc. You can set the default value for $HISTSIZE at build time in config-top.h.
dd. The `complete' builtin now accepts a -I option that applies the completion
to the initial word on the line.
ee. The internal bash malloc now uses mmap (if available) to satisfy requests
greater than 128K bytes, so free can use mfree to return the pages to the
kernel.
ff. The shell doesn't automatically set BASH_ARGC and BASH_ARGV at startup
unless it's in debugging mode, as the documentation has always said, but
will dynamically create them if a script references them at the top level
without having enabled debugging mode.
gg. The localvar_inherit option will not attempt to inherit a value from a
variable of an incompatible type (indexed vs. associative arrays, for
example).
hh. The `globasciiranges' option is now enabled by default; it can be set to
off by default at configuration time.
ii. Associative and indexed arrays now allow subscripts consisting solely of
whitespace.
jj. `checkwinsize' is now enabled by default.
kk. The `localvar_unset' shopt option is now visible and documented.
ll. The `progcomp_alias' shopt option is now visible and documented.
mm. The signal name processing code now understands `SIGRTMIN+n' all the way
up to SIGRTMAX.
nn. There is a new `seq' loadable builtin.
oo. Trap execution now honors the (internal) max invocations of `eval', since
traps are supposed to be executed as if using `eval'.
pp. The $_ variable doesn't change when the shell executes a command that forks.
qq. The `kill' builtin now supports -sSIGNAME and -nSIGNUM, even though
conforming applications aren't supposed to use them.
rr. POSIX mode now enables the `shift_verbose' option.
2. New Features in Readline
a. Non-incremental vi-mode search (`N', `n') can search for a shell pattern, as
Posix specifies (uses fnmatch(3) if available).
b. There are new `next-screen-line' and `previous-screen-line' bindable
commands, which move the cursor to the same column in the next, or previous,
physical line, respectively.
c. There are default key bindings for control-arrow-key key combinations.
d. A negative argument (-N) to `quoted-insert' means to insert the next N
characters using quoted-insert.
e. New public function: rl_check_signals(), which allows applications to
respond to signals that readline catches while waiting for input using
a custom read function.
f. There is new support for conditionally testing the readline version in an
inputrc file, with a full set of arithmetic comparison operators available.
g. There is a simple variable comparison facility available for use within an
inputrc file. Allowable operators are equality and inequality; string
variables may be compared to a value; boolean variables must be compared to
either `on' or `off'; variable names are separated from the operator by
whitespace.
h. The history expansion library now understands command and process
substitution and extended globbing and allows them to appear anywhere in a
word.
i. The history library has a new variable that allows applications to set the
initial quoting state, so quoting state can be inherited from a previous
line.
j. Readline now allows application-defined keymap names; there is a new public
function, rl_set_keymap_name(), to do that.
k. The "Insert" keypad key, if available, now puts readline into overwrite
mode.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-4.4 since
the release of bash-4.3. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. There is now a settable configuration #define that will cause the shell
to exit if the shell is running setuid without the -p option and setuid
to the real uid fails.
b. Command and process substitutions now turn off the `-v' option when
executing, as other shells seem to do.
c. The default value for the `checkhash' shell option may now be set at
compile time with a #define.
d. The `mapfile' builtin now has a -d option to use an arbitrary character
as the record delimiter, and a -t option to strip the delimiter as
supplied with -d.
e. The maximum number of nested recursive calls to `eval' is now settable in
config-top.h; the default is no limit.
f. The `-p' option to declare and similar builtins will display attributes for
named variables even when those variables have not been assigned values
(which are technically unset).
g. The maximum number of nested recursive calls to `source' is now settable
in config-top.h; the default is no limit.
h. All builtin commands recognize the `--help' option and print a usage
summary.
i. Bash does not allow function names containing `/' and `=' to be exported.
j. The `ulimit' builtin has new -k (kqueues) and -P (pseudoterminals) options.
k. The shell now allows `time ; othercommand' to time null commands.
l. There is a new `--enable-function-import' configuration option to allow
importing shell functions from the environment; import is enabled by
default.
m. `printf -v var ""' will now set `var' to the empty string, as if `var=""'
had been executed.
n. GLOBIGNORE, the pattern substitution word expansion, and programmable
completion match filtering now honor the value of the `nocasematch' option.
o. There is a new ${parameter@spec} family of operators to transform the
value of `parameter'.
p. Bash no longer attempts to perform compound assignment if a variable on the
rhs of an assignment statement argument to `declare' has the form of a
compound assignment (e.g., w='(word)' ; declare foo=$w); compound
assignments are accepted if the variable was already declared as an array,
but with a warning.
q. The declare builtin no longer displays array variables using the compound
assignment syntax with quotes; that will generate warnings when re-used as
input, and isn't necessary.
r. Executing the rhs of && and || will no longer cause the shell to fork if
it's not necessary.
s. The `local' builtin takes a new argument: `-', which will cause it to save
and the single-letter shell options and restore their previous values at
function return.
t. `complete' and `compgen' have a new `-o nosort' option, which forces
readline to not sort the completion matches.
u. Bash now allows waiting for the most recent process substitution, since it
appears as $!.
v. The `unset' builtin now unsets a scalar variable if it is subscripted with
a `0', analogous to the ${var[0]} expansion.
w. `set -i' is no longer valid, as in other shells.
x. BASH_SUBSHELL is now updated for process substitution and group commands
in pipelines, and is available with the same value when running any exit
trap.
y. Bash now checks $INSIDE_EMACS as well as $EMACS when deciding whether or
not bash is being run in a GNU Emacs shell window.
z. Bash now treats SIGINT received when running a non-builtin command in a
loop the way it has traditionally treated running a builtin command:
running any trap handler and breaking out of the loop.
aa. New variable: EXECIGNORE; a colon-separate list of patterns that will
cause matching filenames to be ignored when searching for commands.
bb. Aliases whose value ends in a shell metacharacter now expand in a way to
allow them to be `pasted' to the next token, which can potentially change
the meaning of a command (e.g., turning `&' into `&&').
cc. `make install' now installs the example loadable builtins and a set of
bash headers to use when developing new loadable builtins.
dd. `enable -f' now attempts to call functions named BUILTIN_builtin_load when
loading BUILTIN, and BUILTIN_builtin_unload when deleting it. This allows
loadable builtins to run initialization and cleanup code.
ee. There is a new BASH_LOADABLES_PATH variable containing a list of directories
where the `enable -f' command looks for shared objects containing loadable
builtins.
ff. The `complete_fullquote' option to `shopt' changes filename completion to
quote all shell metacharacters in filenames and directory names.
gg. The `kill' builtin now has a `-L' option, equivalent to `-l', for
compatibility with Linux standalone versions of kill.
hh. BASH_COMPAT and FUNCNEST can be inherited and set from the shell's initial
environment.
ii. inherit_errexit: a new `shopt' option that, when set, causes command
substitutions to inherit the -e option. By default, those subshells disable
-e. It's enabled as part of turning on posix mode.
jj. New prompt string: PS0. Expanded and displayed by interactive shells after
reading a complete command but before executing it.
kk. Interactive shells now behave as if SIGTSTP/SIGTTIN/SIGTTOU are set to
SIG_DFL when the shell is started, so they are set to SIG_DFL in child
processes.
ll. Posix-mode shells now allow double quotes to quote the history expansion
character.
mm. OLDPWD can be inherited from the environment if it names a directory.
nn. Shells running as root no longer inherit PS4 from the environment, closing
a security hole involving PS4 expansion performing command substitution.
oo. If executing an implicit `cd' when the `autocd' option is set, bash will
now invoke a function named `cd' if one exists before executing the `cd'
builtin.
pp. Value conversions (arithmetic expansions, case modification, etc.) now
happen when assigning elements of an array using compound assignment.
qq. There is a new option settable in config-top.h that makes multiple
directory arguments to `cd' a fatal error.
rr. Bash now uses mktemp() when creating internal temporary files; it produces
a warning at build time on many Linux systems.
2. New Features in Readline
a. The history truncation code now uses the same error recovery mechanism as
the history writing code, and restores the old version of the history file
on error. The error recovery mechanism handles symlinked history files.
b. There is a new bindable variable, `enable-bracketed-paste', which enables
support for a terminal's bracketed paste mode.
c. The editing mode indicators can now be strings and are user-settable
(new `emacs-mode-string', `vi-cmd-mode-string' and `vi-ins-mode-string'
variables). Mode strings can contain invisible character sequences.
Setting mode strings to null strings restores the defaults.
d. Prompt expansion adds the mode string to the last line of a multi-line
prompt (one with embedded newlines).
e. There is a new bindable variable, `colored-completion-prefix', which, if
set, causes the common prefix of a set of possible completions to be
displayed in color.
f. There is a new bindable command `vi-yank-pop', a vi-mode version of emacs-
mode yank-pop.
g. The redisplay code underwent several efficiency improvements for multibyte
locales.
h. The insert-char function attempts to batch-insert all pending typeahead
that maps to self-insert, as long as it is coming from the terminal.
i. rl_callback_sigcleanup: a new application function that can clean up and
unset any state set by readline's callback mode. Intended to be used
after a signal.
j. If an incremental search string has its last character removed with DEL, the
resulting empty search string no longer matches the previous line.
k. If readline reads a history file that begins with `#' (or the value of
the history comment character) and has enabled history timestamps, the
history entries are assumed to be delimited by timestamps. This allows
multi-line history entries.
l. Readline now throws an error if it parses a key binding without a
terminating `:' or whitespace.
m. The default binding for ^W in vi mode now uses word boundaries specified
by Posix (vi-unix-word-rubout is bindable command name).
n. rl_clear_visible_line: new application-callable function; clears all
screen lines occupied by the current visible readline line.
o. rl_tty_set_echoing: application-callable function that controls whether
or not readline thinks it is echoing terminal output.
p. Handle >| and strings of digits preceding and following redirection
specifications as single tokens when tokenizing the line for history
expansion.
q. Fixed a bug with displaying completions when the prefix display length
is greater than the length of the completions to be displayed.
r. The :p history modifier now applies to the entire line, so any expansion
specifying :p causes the line to be printed instead of expanded.
s. New application-callable function: rl_pending_signal(): returns the signal
number of any signal readline has caught but not yet handled.
t. New application-settable variable: rl_persistent_signal_handlers: if set
to a non-zero value, readline will enable the readline-6.2 signal handler
behavior in callback mode: handlers are installed when
rl_callback_handler_install is called and removed removed when a complete
line has been read.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-4.3 since
the release of bash-4.2. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. The `helptopic' completion action now maps to all the help topics, not just
the shell builtins.
b. The `help' builtin no longer does prefix substring matching first, so
`help read' does not match `readonly', but will do it if exact string
matching fails.
c. The shell can be compiled to not display a message about processes that
terminate due to SIGTERM.
d. Non-interactive shells now react to the setting of checkwinsize and set
LINES and COLUMNS after a foreground job exits.
e. There is a new shell option, `globasciiranges', which, when set to on,
forces globbing range comparisons to use character ordering as if they
were run in the C locale.
f. There is a new shell option, `direxpand', which makes filename completion
expand variables in directory names in the way bash-4.1 did.
g. In Posix mode, the `command' builtin does not change whether or not a
builtin it shadows is treated as an assignment builtin.
h. The `return' and `exit' builtins accept negative exit status arguments.
i. The word completion code checks whether or not a filename containing a
shell variable expands to a directory name and appends `/' to the word
as appropriate. The same code expands shell variables in command names
when performing command completion.
j. In Posix mode, it is now an error to attempt to define a shell function
with the same name as a Posix special builtin.
k. When compiled for strict Posix conformance, history expansion is disabled
by default.
l. The history expansion character (!) does not cause history expansion when
followed by the closing quote in a double-quoted string.
m. `complete' and its siblings compgen/compopt now takes a new `-o noquote'
option to inhibit quoting of the completions.
n. Setting HISTSIZE to a value less than zero causes the history list to be
unlimited (setting it 0 zero disables the history list).
o. Setting HISTFILESIZE to a value less than zero causes the history file size
to be unlimited (setting it to 0 causes the history file to be truncated
to zero size).
p. The `read' builtin now skips NUL bytes in the input.
q. There is a new `bind -X' option to print all key sequences bound to Unix
commands.
r. When in Posix mode, `read' is interruptible by a trapped signal. After
running the trap handler, read returns 128+signal and throws away any
partially-read input.
s. The command completion code skips whitespace and assignment statements
before looking for the command name word to be completed.
t. The build process has a new mechanism for constructing separate help files
that better reflects the current set of compilation options.
u. The -nt and -ot options to test now work with files with nanosecond
timestamp resolution.
v. The shell saves the command history in any shell for which history is
enabled and HISTFILE is set, not just interactive shells.
w. The shell has `nameref' variables and new -n(/+n) options to declare and
unset to use them, and a `test -R' option to test for them.
x. The shell now allows assigning, referencing, and unsetting elements of
indexed arrays using negative subscripts (a[-1]=2, echo ${a[-1]}) which
count back from the last element of the array.
y. The {x}<word redirection feature now allows words like {array[ind]} and
can use variables with special meanings to the shell (e.g., BASH_XTRACEFD).
z. There is a new CHILD_MAX special shell variable; its value controls the
number of exited child statues the shell remembers.
aa. There is a new configuration option (--enable-direxpand-default) that
causes the `direxpand' shell option to be enabled by default.
bb. Bash does not do anything special to ensure that the file descriptor
assigned to X in {x}<foo remains open after the block containing it
completes.
cc. The `wait' builtin has a new `-n' option to wait for the next child to
change status.
dd. The `printf' %(...)T format specifier now uses the current time if no
argument is supplied.
ee. There is a new variable, BASH_COMPAT, that controls the current shell
compatibility level.
ff. The `popd' builtin now treats additional arguments as errors.
gg. The brace expansion code now treats a failed sequence expansion as a
simple string and will continue to expand brace terms in the remainder
of the word.
hh. Shells started to run process substitutions now run any trap set on EXIT.
ii. The fc builtin now interprets -0 as the current command line.
jj. Completing directory names containing shell variables now adds a trailing
slash if the expanded result is a directory.
kk. `cd' has a new `-@' option to browse a file's extended attributes on
systems that support O_XATTR.
ll. The test/[/[[ `-v variable' binary operator now understands array
references.
2. New Features in Readline
a. Readline is now more responsive to SIGHUP and other fatal signals when
reading input from the terminal or performing word completion but no
longer attempts to run any not-allowable functions from a signal handler
context.
b. There are new bindable commands to search the history for the string of
characters between the beginning of the line and the point
(history-substring-search-forward, history-substring-search-backward)
c. Readline allows quoted strings as the values of variables when setting
them with `set'. As a side effect, trailing spaces and tabs are ignored
when setting a string variable's value.
d. The history library creates a backup of the history file when writing it
and restores the backup on a write error.
e. New application-settable variable: rl_filename_stat_hook: a function called
with a filename before using it in a call to stat(2). Bash uses it to
expand shell variables so things like $HOME/Downloads have a slash
appended.
f. New bindable function `print-last-kbd-macro', prints the most-recently-
defined keyboard macro in a reusable format.
g. New user-settable variable `colored-stats', enables use of colored text
to denote file types when displaying possible completions (colored analog
of visible-stats).
h. New user-settable variable `keyseq-timout', acts as an inter-character
timeout when reading input or incremental search strings.
i. New application-callable function: rl_clear_history. Clears the history list
and frees all readline-associated private data.
j. New user-settable variable, show-mode-in-prompt, adds a characters to the
beginning of the prompt indicating the current editing mode.
k. New application-settable variable: rl_input_available_hook; function to be
called when readline detects there is data available on its input file
descriptor.
l. Readline calls an application-set event hook (rl_event_hook) after it gets
a signal while reading input (read returns -1/EINTR but readline does not
handle the signal immediately) to allow the application to handle or
otherwise note it.
m. If the user-settable variable `history-size' is set to a value less than
0, the history list size is unlimited.
n. New application-settable variable: rl_signal_event_hook; function that is
called when readline is reading terminal input and read(2) is interrupted
by a signal. Currently not called for SIGHUP or SIGTERM.
o. rl_change_environment: new application-settable variable that controls
whether or not Readline modifies the environment (currently readline
modifies only LINES and COLUMNS).
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-4.2 since
the release of bash-4.1. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. `exec -a foo' now sets $0 to `foo' in an executable shell script without a
leading #!.
b. Subshells begun to execute command substitutions or run shell functions or
builtins in subshells do not reset trap strings until a new trap is
specified. This allows $(trap) to display the caller's traps and the
trap strings to persist until a new trap is set.
c. `trap -p' will now show signals ignored at shell startup, though their
disposition still cannot be modified.
d. $'...', echo, and printf understand \uXXXX and \UXXXXXXXX escape sequences.
e. declare/typeset has a new `-g' option, which creates variables in the
global scope even when run in a shell function.
f. test/[/[[ have a new -v variable unary operator, which returns success if
`variable' has been set.
g. Posix parsing changes to allow `! time command' and multiple consecutive
instances of `!' (which toggle) and `time' (which have no cumulative
effect).
h. Posix change to allow `time' as a command by itself to print the elapsed
user, system, and real times for the shell and its children.
j. $((...)) is always parsed as an arithmetic expansion first, instead of as
a potential nested command substitution, as Posix requires.
k. A new FUNCNEST variable to allow the user to control the maximum shell
function nesting (recursive execution) level.
l. The mapfile builtin now supplies a third argument to the callback command:
the line about to be assigned to the supplied array index.
m. The printf builtin has a new %(fmt)T specifier, which allows time values
to use strftime-like formatting.
n. There is a new `compat41' shell option.
o. The cd builtin has a new Posix-mandated `-e' option.
p. Negative subscripts to indexed arrays, previously errors, now are treated
as offsets from the maximum assigned index + 1.
q. Negative length specifications in the ${var:offset:length} expansion,
previously errors, are now treated as offsets from the end of the variable.
r. Parsing change to allow `time -p --'.
s. Posix-mode parsing change to not recognize `time' as a keyword if the
following token begins with a `-'. This means no more Posix-mode
`time -p'. Posix interpretation 267.
t. There is a new `lastpipe' shell option that runs the last command of a
pipeline in the current shell context. The lastpipe option has no
effect if job control is enabled.
u. History expansion no longer expands the `$!' variable expansion.
v. Posix mode shells no longer exit if a variable assignment error occurs
with an assignment preceding a command that is not a special builtin.
w. Non-interactive mode shells exit if -u is enabled and an attempt is made
to use an unset variable with the % or # expansions, the `//', `^', or
`,' expansions, or the parameter length expansion.
x. Posix-mode shells use the argument passed to `.' as-is if a $PATH search
fails, effectively searching the current directory. Posix-2008 change.
2. New Features in Readline
a. The history library does not try to write the history filename in the
current directory if $HOME is unset. This closes a potential security
problem if the application does not specify a history filename.
b. New bindable variable `completion-display-width' to set the number of
columns used when displaying completions.
c. New bindable variable `completion-case-map' to cause case-insensitive
completion to treat `-' and `_' as identical.
d. There are new bindable vi-mode command names to avoid readline's case-
insensitive matching not allowing them to be bound separately.
e. New bindable variable `menu-complete-display-prefix' causes the menu
completion code to display the common prefix of the possible completions
before cycling through the list, instead of after.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-4.1 since
the release of bash-4.0. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. Here-documents within $(...) command substitutions may once more be
delimited by the closing right paren, instead of requiring a newline.
b. Bash's file status checks (executable, readable, etc.) now take file
system ACLs into account on file systems that support them.
c. Bash now passes environment variables with names that are not valid
shell variable names through into the environment passed to child
processes.
d. The `execute-unix-command' readline function now attempts to clear and
reuse the current line rather than move to a new one after the command
executes.
e. `printf -v' can now assign values to array indices.
f. New `complete -E' and `compopt -E' options that work on the "empty"
completion: completion attempted on an empty command line.
g. New complete/compgen/compopt -D option to define a `default' completion:
a completion to be invoked on command for which no completion has been
defined. If this function returns 124, programmable completion is
attempted again, allowing a user to dynamically build a set of completions
as completion is attempted by having the default completion function
install individual completion functions each time it is invoked.
h. When displaying associative arrays, subscripts are now quoted.
i. Changes to dabbrev-expand to make it more `emacs-like': no space appended
after matches, completions are not sorted, and most recent history entries
are presented first.
j. The [[ and (( commands are now subject to the setting of `set -e' and the
ERR trap.
k. The source/. builtin now removes NUL bytes from the file before attempting
to parse commands.
l. There is a new configuration option (in config-top.h) that forces bash to
forward all history entries to syslog.
m. A new variable $BASHOPTS to export shell options settable using `shopt' to
child processes.
n. There is a new configure option that forces the extglob option to be
enabled by default.
o. New variable $BASH_XTRACEFD; when set to an integer bash will write xtrace
output to that file descriptor.
p. If the optional left-hand-side of a redirection is of the form {var}, the
shell assigns the file descriptor used to $var or uses $var as the file
descriptor to move or close, depending on the redirection operator.
q. The < and > operators to the [[ conditional command now do string
comparison according to the current locale if the compatibility level
is greater than 40.
r. Programmable completion now uses the completion for `b' instead of `a'
when completion is attempted on a line like: a $(b c.
s. Force extglob on temporarily when parsing the pattern argument to
the == and != operators to the [[ command, for compatibility.
t. Changed the behavior of interrupting the wait builtin when a SIGCHLD is
received and a trap on SIGCHLD is set to be Posix-mode only.
u. The read builtin has a new `-N nchars' option, which reads exactly NCHARS
characters, ignoring delimiters like newline.
v. The mapfile/readarray builtin no longer stores the commands it invokes via
callbacks in the history list.
w. There is a new `compat40' shopt option.
2. New Features in Readline
a. New bindable function: menu-complete-backward.
b. In the vi insertion keymap, C-n is now bound to menu-complete by default,
and C-p to menu-complete-backward.
c. When in vi command mode, repeatedly hitting ESC now does nothing, even
when ESC introduces a bound key sequence. This is closer to how
historical vi behaves.
d. New bindable function: skip-csi-sequence. Can be used as a default to
consume key sequences generated by keys like Home and End without having
to bind all keys.
e. New application-settable function: rl_filename_rewrite_hook. Can be used
to rewrite or modify filenames read from the file system before they are
compared to the word to be completed.
f. New bindable variable: skip-completed-text, active when completing in the
middle of a word. If enabled, it means that characters in the completion
that match characters in the remainder of the word are "skipped" rather
than inserted into the line.
g. The pre-readline-6.0 version of menu completion is available as
"old-menu-complete" for users who do not like the readline-6.0 version.
h. New bindable variable: echo-control-characters. If enabled, and the
tty ECHOCTL bit is set, controls the echoing of characters corresponding
to keyboard-generated signals.
i. New bindable variable: enable-meta-key. Controls whether or not readline
sends the smm/rmm sequences if the terminal indicates it has a meta key
that enables eight-bit characters.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-4.0 since
the release of bash-3.2. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. When using substring expansion on the positional parameters, a starting
index of 0 now causes $0 to be prefixed to the list.
b. The `help' builtin now prints its columns with entries sorted vertically
rather than horizontally.
c. There is a new variable, $BASHPID, which always returns the process id of
the current shell.
d. There is a new `autocd' option that, when enabled, causes bash to attempt
to `cd' to a directory name that is supplied as the first word of a
simple command.
e. There is a new `checkjobs' option that causes the shell to check for and
report any running or stopped jobs at exit.
f. The programmable completion code exports a new COMP_TYPE variable, set to
a character describing the type of completion being attempted.
g. The programmable completion code exports a new COMP_KEY variable, set to
the character that caused the completion to be invoked (e.g., TAB).
h. If creation of a child process fails due to insufficient resources, bash
will try again several times before reporting failure.
i. The programmable completion code now uses the same set of characters as
readline when breaking the command line into a list of words.
j. The block multiplier for the ulimit -c and -f options is now 512 when in
Posix mode, as Posix specifies.
k. Changed the behavior of the read builtin to save any partial input received
in the specified variable when the read builtin times out. This also
results in variables specified as arguments to read to be set to the empty
string when there is no input available. When the read builtin times out,
it returns an exit status greater than 128.
l. The shell now has the notion of a `compatibility level', controlled by
new variables settable by `shopt'. Setting this variable currently
restores the bash-3.1 behavior when processing quoted strings on the rhs
of the `=~' operator to the `[[' command.
m. The `ulimit' builtin now has new -b (socket buffer size) and -T (number
of threads) options.
n. The -p option to `declare' now displays all variable values and attributes
(or function values and attributes if used with -f).
o. There is a new `compopt' builtin that allows completion functions to modify
completion options for existing completions or the completion currently
being executed.
p. The `read' builtin has a new -i option which inserts text into the reply
buffer when using readline.
q. A new `-E' option to the complete builtin allows control of the default
behavior for completion on an empty line.
r. There is now limited support for completing command name words containing
globbing characters.
s. Changed format of internal help documentation for all builtins to roughly
follow man page format.
t. The `help' builtin now has a new -d option, to display a short description,
and a -m option, to print help information in a man page-like format.
u. There is a new `mapfile' builtin to populate an array with lines from a
given file. The name `readarray' is a synonym.
v. If a command is not found, the shell attempts to execute a shell function
named `command_not_found_handle', supplying the command words as the
function arguments.
w. There is a new shell option: `globstar'. When enabled, the globbing code
treats `**' specially -- it matches all directories (and files within
them, when appropriate) recursively.
x. There is a new shell option: `dirspell'. When enabled, the filename
completion code performs spelling correction on directory names during
completion.
y. The `-t' option to the `read' builtin now supports fractional timeout
values.
z. Brace expansion now allows zero-padding of expanded numeric values and
will add the proper number of zeroes to make sure all values contain the
same number of digits.
aa. There is a new bash-specific bindable readline function: `dabbrev-expand'.
It uses menu completion on a set of words taken from the history list.
bb. The command assigned to a key sequence with `bind -x' now sets two new
variables in the environment of the executed command: READLINE_LINE_BUFFER
and READLINE_POINT. The command can change the current readline line
and cursor position by modifying READLINE_LINE_BUFFER and READLINE_POINT,
respectively.
cc. There is a new &>> redirection operator, which appends the standard output
and standard error to the named file.
dd. The parser now understands `|&' as a synonym for `2>&1 |', which redirects
the standard error for a command through a pipe.
ee. The new `;&' case statement action list terminator causes execution to
continue with the action associated with the next pattern in the
statement rather than terminating the command.
ff. The new `;;&' case statement action list terminator causes the shell to
test the next set of patterns after completing execution of the current
action, rather than terminating the command.
gg. The shell understands a new variable: PROMPT_DIRTRIM. When set to an
integer value greater than zero, prompt expansion of \w and \W will
retain only that number of trailing pathname components and replace
the intervening characters with `...'.
hh. There are new case-modifying word expansions: uppercase (^[^]) and
lowercase (,[,]). They can work on either the first character or
array element, or globally. They accept an optional shell pattern
that determines which characters to modify. There is an optionally-
configured feature to include capitalization operators.
ii. The shell provides associative array variables, with the appropriate
support to create, delete, assign values to, and expand them.
jj. The `declare' builtin now has new -l (convert value to lowercase upon
assignment) and -u (convert value to uppercase upon assignment) options.
There is an optionally-configurable -c option to capitalize a value at
assignment.
kk. There is a new `coproc' reserved word that specifies a coprocess: an
asynchronous command run with two pipes connected to the creating shell.
Coprocs can be named. The input and output file descriptors and the
PID of the coprocess are available to the calling shell in variables
with coproc-specific names.
ll. A value of 0 for the -t option to `read' now returns success if there is
input available to be read from the specified file descriptor.
mm. CDPATH and GLOBIGNORE are ignored when the shell is running in privileged
mode.
nn. New bindable readline functions shell-forward-word and shell-backward-word,
which move forward and backward words delimited by shell metacharacters
and honor shell quoting.
oo. New bindable readline functions shell-backward-kill-word and shell-kill-word
which kill words backward and forward, but use the same word boundaries
as shell-forward-word and shell-backward-word.
2. New Features in Readline
a. A new variable, rl_sort_completion_matches; allows applications to inhibit
match list sorting (but beware: some things don't work right if
applications do this).
b. A new variable, rl_completion_invoking_key; allows applications to discover
the key that invoked rl_complete or rl_menu_complete.
c. The functions rl_block_sigint and rl_release_sigint are now public and
available to calling applications who want to protect critical sections
(like redisplay).
d. The functions rl_save_state and rl_restore_state are now public and
available to calling applications; documented rest of readline's state
flag values.
e. A new user-settable variable, `history-size', allows setting the maximum
number of entries in the history list.
f. There is a new implementation of menu completion, with several improvements
over the old; the most notable improvement is a better `completions
browsing' mode.
g. The menu completion code now uses the rl_menu_completion_entry_function
variable, allowing applications to provide their own menu completion
generators.
h. There is support for replacing a prefix of a pathname with a `...' when
displaying possible completions. This is controllable by setting the
`completion-prefix-display-length' variable. Matches with a common prefix
longer than this value have the common prefix replaced with `...'.
i. There is a new `revert-all-at-newline' variable. If enabled, readline will
undo all outstanding changes to all history lines when `accept-line' is
executed.
j. If the kernel supports it, readline displays special characters
corresponding to a keyboard-generated signal when the signal is received.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-3.2 since
the release of bash-3.1. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. Changed the parameter pattern replacement functions to not anchor the
pattern at the beginning of the string if doing global replacement - that
combination doesn't make any sense.
b. When running in `word expansion only' mode (--wordexp option), inhibit
process substitution.
c. Loadable builtins now work on MacOS X 10.[34].
d. Shells running in posix mode no longer set $HOME, as POSIX requires.
e. The code that checks for binary files being executed as shell scripts now
checks only for NUL rather than any non-printing character.
f. Quoting the string argument to the [[ command's =~ operator now forces
string matching, as with the other pattern-matching operators.
2. New Features in Readline
a. Calling applications can now set the keyboard timeout to 0, allowing
poll-like behavior.
b. The value of SYS_INPUTRC (configurable at compilation time) is now used as
the default last-ditch startup file.
c. The history file reading functions now allow windows-like \r\n line
terminators.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-3.1 since
the release of bash-3.0. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. Bash now understands LC_TIME as a special variable so that time display
tracks the current locale.
b. BASH_ARGC, BASH_ARGV, BASH_SOURCE, and BASH_LINENO are no longer created
as `invisible' variables and may not be unset.
c. In POSIX mode, if `xpg_echo' option is enabled, the `echo' builtin doesn't
try to interpret any options at all, as POSIX requires.
d. The `bg' builtin now accepts multiple arguments, as POSIX seems to specify.
e. Fixed vi-mode word completion and glob expansion to perform tilde
expansion.
f. The `**' mathematic exponentiation operator is now right-associative.
g. The `ulimit' builtin has new options: -i (max number of pending signals),
-q (max size of POSIX message queues), and -x (max number of file locks).
h. A bare `%' once again expands to the current job when used as a job
specifier.
i. The `+=' assignment operator (append to the value of a string or array) is
now supported for assignment statements and arguments to builtin commands
that accept assignment statements.
j. BASH_COMMAND now preserves its value when a DEBUG trap is executed.
k. The `gnu_errfmt' option is enabled automatically if the shell is running
in an emacs terminal window.
l. New configuration option: --single-help-strings. Causes long help text
to be written as a single string; intended to ease translation.
m. The COMP_WORDBREAKS variable now causes the list of word break characters
to be emptied when the variable is unset.
n. An unquoted expansion of $* when $IFS is empty now causes the positional
parameters to be concatenated if the expansion doesn't undergo word
splitting.
o. Bash now inherits $_ from the environment if it appears there at startup.
p. New shell option: nocasematch. If non-zero, shell pattern matching ignores
case when used by `case' and `[[' commands.
q. The `printf' builtin takes a new option: -v var. That causes the output
to be placed into var instead of on stdout.
r. By default, the shell no longer reports processes dying from SIGPIPE.
s. Bash now sets the extern variable `environ' to the export environment it
creates, so C library functions that call getenv() (and can't use the
shell-provided replacement) get current values of environment variables.
t. A new configuration option, `--enable-strict-posix-default', which will
build bash to be POSIX conforming by default.
u. If compiled for strict POSIX conformance, LINES and COLUMNS may now
override the true terminal size.
2. New Features in Readline
a. The key sequence sent by the keypad `delete' key is now automatically
bound to delete-char.
b. A negative argument to menu-complete now cycles backward through the
completion list.
c. A new bindable readline variable: bind-tty-special-chars. If non-zero,
readline will bind the terminal special characters to their readline
equivalents when it's called (on by default).
d. New bindable command: vi-rubout. Saves deleted text for possible
reinsertion, as with any vi-mode `text modification' command; `X' is bound
to this in vi command mode.
e. A new external application-controllable variable that allows the LINES
and COLUMNS environment variables to set the window size regardless of
what the kernel returns: rl_prefer_env_winsize
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-3.0 since
the release of bash-2.05b. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. ANSI string expansion now implements the \x{hexdigits} escape.
b. There is a new loadable `strftime' builtin.
c. New variable, COMP_WORDBREAKS, which controls the readline completer's
idea of word break characters.
d. The `type' builtin no longer reports on aliases unless alias expansion
will actually be performed.
e. HISTCONTROL is now a colon-separated list of values, which permits
more extensibility and backwards compatibility.
f. HISTCONTROL may now include the `erasedups' option, which causes all lines
matching a line being added to be removed from the history list.
g. `configure' has a new `--enable-multibyte' argument that permits multibyte
character support to be disabled even on systems that support it.
h. New variables to support the bash debugger: BASH_ARGC, BASH_ARGV,
BASH_SOURCE, BASH_LINENO, BASH_SUBSHELL, BASH_EXECUTION_STRING,
BASH_COMMAND
i. FUNCNAME has been changed to support the debugger: it's now an array
variable.
j. for, case, select, arithmetic commands now keep line number information
for the debugger.
k. There is a new `RETURN' trap executed when a function or sourced script
returns (not inherited child processes; inherited by command substitution
if function tracing is enabled and the debugger is active).
l. New invocation option: --debugger. Enables debugging and turns on new
`extdebug' shell option.
m. New `functrace' and `errtrace' options to `set -o' cause DEBUG and ERR
traps, respectively, to be inherited by shell functions. Equivalent to
`set -T' and `set -E' respectively. The `functrace' option also controls
whether or not the DEBUG trap is inherited by sourced scripts.
n. The DEBUG trap is run before binding the variable and running the action
list in a `for' command, binding the selection variable and running the
query in a `select' command, and before attempting a match in a `case'
command.
o. New `--enable-debugger' option to `configure' to compile in the debugger
support code.
p. `declare -F' now prints out extra line number and source file information
if the `extdebug' option is set.
q. If `extdebug' is enabled, a non-zero return value from a DEBUG trap causes
the next command to be skipped, and a return value of 2 while in a
function or sourced script forces a `return'.
r. New `caller' builtin to provide a call stack for the bash debugger.
s. The DEBUG trap is run just before the first command in a function body is
executed, for the debugger.
t. `for', `select', and `case' command heads are printed when `set -x' is
enabled.
u. There is a new {x..y} brace expansion, which is shorthand for {x.x+1,
x+2,...,y}. x and y can be integers or single characters; the sequence
may ascend or descend; the increment is always 1.
v. New ksh93-like ${!array[@]} expansion, expands to all the keys (indices)
of array.
w. New `force_fignore' shopt option; if enabled, suffixes specified by
FIGNORE cause words to be ignored when performing word completion even
if they're the only possibilities.
x. New `gnu_errfmt' shopt option; if enabled, error messages follow the `gnu
style' (filename:lineno:message) format.
y. New `-o bashdefault' option to complete and compgen; if set, causes the
whole set of bash completions to be performed if the compspec doesn't
result in a match.
z. New `-o plusdirs' option to complete and compgen; if set, causes directory
name completion to be performed and the results added to the rest of the
possible completions.
aa. `kill' is available as a builtin even when the shell is built without
job control.
bb. New HISTTIMEFORMAT variable; value is a format string to pass to
strftime(3). If set and not null, the `history' builtin prints out
timestamp information according to the specified format when displaying
history entries. If set, bash tells the history library to write out
timestamp information when the history file is written.
cc. The [[ ... ]] command has a new binary `=~' operator that performs
extended regular expression (egrep-like) matching.
dd. `configure' has a new `--enable-cond-regexp' option (enabled by default)
to enable the =~ operator and regexp matching in [[ ... ]].
ee. Subexpressions matched by the =~ operator are placed in the new
BASH_REMATCH array variable.
ff. New `failglob' option that causes an expansion error when pathname
expansion fails to produce a match.
gg. New `set -o pipefail' option that causes a pipeline to return a failure
status if any of the processes in the pipeline fail, not just the last
one.
hh. printf builtin understands two new escape sequences: \" and \?.
ii. `echo -e' understands two new escape sequences: \" and \?.
jj. The GNU `gettext' package and libintl have been integrated; the shell's
messages can be translated into different languages.
kk. The `\W' prompt expansion now abbreviates $HOME as `~', like `\w'.
ll. The error message printed when bash cannot open a shell script supplied
as argument 1 now includes the name of the shell, to better identify
the error as coming from bash.
mm. The parameter pattern removal and substitution expansions are now much
faster and more efficient when using multibyte characters.
nn. The `jobs', `kill', and `wait' builtins now accept job control notation
even if job control is not enabled.
oo. The historical behavior of `trap' that allows a missing `action' argument
to cause each specified signal's handling to be reset to its default is
now only supported when `trap' is given a single non-option argument.
2. New Features in Readline
a. History expansion has a new `a' modifier equivalent to the `g' modifier
for compatibility with the BSD csh.
b. History expansion has a new `G' modifier equivalent to the BSD csh `g'
modifier, which performs a substitution once per word.
c. All non-incremental search operations may now undo the operation of
replacing the current line with the history line.
d. The text inserted by an `a' command in vi mode can be reinserted with
`.'.
e. New bindable variable, `show-all-if-unmodified'. If set, the readline
completer will list possible completions immediately if there is more
than one completion and partial completion cannot be performed.
f. There is a new application-callable `free_history_entry()' function.
g. History list entries now contain timestamp information; the history file
functions know how to read and write timestamp information associated
with each entry.
h. Four new key binding functions have been added:
rl_bind_key_if_unbound()
rl_bind_key_if_unbound_in_map()
rl_bind_keyseq_if_unbound()
rl_bind_keyseq_if_unbound_in_map()
i. New application variable, rl_completion_quote_character, set to any
quote character readline finds before it calls the application completion
function.
j. New application variable, rl_completion_suppress_quote, settable by an
application completion function. If set to non-zero, readline does not
attempt to append a closing quote to a completed word.
k. New application variable, rl_completion_found_quote, set to a non-zero
value if readline determines that the word to be completed is quoted.
Set before readline calls any application completion function.
l. New function hook, rl_completion_word_break_hook, called when readline
needs to break a line into words when completion is attempted. Allows
the word break characters to vary based on position in the line.
m. New bindable command: unix-filename-rubout. Does the same thing as
unix-word-rubout, but adds `/' to the set of word delimiters.
n. When listing completions, directories have a `/' appended if the
`mark-directories' option has been enabled.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.05b since
the release of bash-2.05a. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. If set, TMOUT is the default timeout for the `read' builtin.
b. `type' has two new options: `-f' suppresses shell function lookup, and
`-P' forces a $PATH search.
c. New code to handle multibyte characters.
d. `select' was changed to be more ksh-compatible, in that the menu is
reprinted each time through the loop only if REPLY is set to NULL.
The previous behavior is available as a compile-time option.
e. `complete -d' and `complete -o dirnames' now force a slash to be
appended to names which are symlinks to directories.
f. There is now a bindable edit-and-execute-command readline command,
like the vi-mode `v' command, bound to C-xC-e in emacs mode.
g. Added support for ksh93-like [:word:] character class in pattern matching.
h. The $'...' quoting construct now expands \cX to Control-X.
i. A new \D{...} prompt expansion; passes the `...' to strftime and inserts
the result into the expanded prompt.
j. The shell now performs arithmetic in the largest integer size the
machine supports (intmax_t), instead of long.
k. If a numeric argument is supplied to one of the bash globbing completion
functions, a `*' is appended to the word before expansion is attempted.
l. The bash globbing completion functions now allow completions to be listed
with double tabs or if `show-all-if-ambiguous' is set.
m. New `-o nospace' option for `complete' and `compgen' builtins; suppresses
readline's appending a space to the completed word.
n. New `here-string' redirection operator: <<< word.
o. When displaying variables, function attributes and definitions are shown
separately, allowing them to be re-used as input (attempting to re-use
the old output would result in syntax errors).
p. There is a new configuration option `--enable-mem-scramble', controls
bash malloc behavior of writing garbage characters into memory at
allocation and free time.
q. The `complete' and `compgen' builtins now have a new `-s/-A service'
option to complete on names from /etc/services.
r. `read' has a new `-u fd' option to read from a specified file descriptor.
s. Fix the completion code so that expansion errors in a directory name
don't cause a longjmp back to the command loop.
t. Fixed word completion inside command substitution to work a little more
intuitively.
u. The `printf' %q format specifier now uses $'...' quoting to print the
argument if it contains non-printing characters.
v. The `declare' and `typeset' builtins have a new `-t' option. When applied
to functions, it causes the DEBUG trap to be inherited by the named
function. Currently has no effect on variables.
w. The DEBUG trap is now run *before* simple commands, ((...)) commands,
[[...]] conditional commands, and for ((...)) loops.
x. The expansion of $LINENO inside a shell function is only relative to the
function start if the shell is interactive -- if the shell is running a
script, $LINENO expands to the line number in the script. This is as
POSIX-2001 requires.
y. The bash debugger in examples/bashdb has been modified to work with the
new DEBUG trap semantics, the command set has been made more gdb-like,
and the changes to $LINENO make debugging functions work better. Code
from Gary Vaughan.
z. New [n]<&word- and [n]>&word- redirections from ksh93 -- move fds (dup
and close).
aa. There is a new `-l' invocation option, equivalent to `--login'.
bb. The `hash' builtin has a new `-l' option to list contents in a reusable
format, and a `-d' option to remove a name from the hash table.
cc. There is now support for placing the long help text into separate files
installed into ${datadir}/bash. Not enabled by default; can be turned
on with `--enable-separate-helpfiles' option to configure.
dd. All builtins that take operands accept a `--' pseudo-option, except
`echo'.
ee. The `echo' builtin now accepts \0xxx (zero to three octal digits following
the `0') in addition to \xxx (one to three octal digits) for SUSv3/XPG6/
POSIX.1-2001 compliance.
2. New Features in Readline
a. Support for key `subsequences': allows, e.g., ESC and ESC-a to both
be bound to readline functions. Now the arrow keys may be used in vi
insert mode.
b. When listing completions, and the number of lines displayed is more than
the screen length, readline uses an internal pager to display the results.
This is controlled by the `page-completions' variable (default on).
c. New code to handle editing and displaying multibyte characters.
d. The behavior introduced in bash-2.05a of deciding whether or not to
append a slash to a completed name that is a symlink to a directory has
been made optional, controlled by the `mark-symlinked-directories'
variable (default is the 2.05a behavior).
e. The `insert-comment' command now acts as a toggle if given a numeric
argument: if the first characters on the line don't specify a
comment, insert one; if they do, delete the comment text
f. New application-settable completion variable:
rl_completion_mark_symlink_dirs, allows an application's completion
function to temporarily override the user's preference for appending
slashes to names which are symlinks to directories.
g. New function available to application completion functions:
rl_completion_mode, to tell how the completion function was invoked
and decide which argument to supply to rl_complete_internal (to list
completions, etc.).
h. Readline now has an overwrite mode, toggled by the `overwrite-mode'
bindable command, which could be bound to `Insert'.
i. New application-settable completion variable:
rl_completion_suppress_append, inhibits appending of
rl_completion_append_character to completed words.
j. New key bindings when reading an incremental search string: ^W yanks
the currently-matched word out of the current line into the search
string; ^Y yanks the rest of the current line into the search string,
DEL or ^H deletes characters from the search string.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.05a since
the release of bash-2.05. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. Added support for DESTDIR installation root prefix, so you can do a
`make install DESTDIR=bash-root' and do easier binary packaging.
b. Added support for builtin printf "'" flag character as per latest POSIX
drafts.
c. Support for POSIX.2 printf(1) length specifiers `j', `t', and `z' (from
ISO C99).
d. New autoconf macro, RL_LIB_READLINE_VERSION, for use by other applications
(bash doesn't use very much of what it returns).
e. `set [-+]o nolog' is recognized as required by the latest POSIX drafts,
but ignored.
f. New read-only `shopt' option: login_shell. Set to non-zero value if the
shell is a login shell.
g. New `\A' prompt string escape sequence; expands to time in 24 HH:MM format.
h. New `-A group/-g' option to complete and compgen; does group name
completion.
i. New `-t' option to `hash' to list hash values for each filename argument.
j. New [-+]O invocation option to set and unset `shopt' options at startup.
k. configure's `--with-installed-readline' option now takes an optional
`=PATH' suffix to set the root of the tree where readline is installed
to PATH.
l. The ksh-like `ERR' trap has been added. The `ERR' trap will be run
whenever the shell would have exited if the -e option were enabled.
It is not inherited by shell functions.
m. `readonly', `export', and `declare' now print variables which have been
given attributes but not set by assigning a value as just a command and
a variable name (like `export foo') when listing, as the latest POSIX
drafts require.
n. `bashbug' now requires that the subject be changed from the default.
o. configure has a new `--enable-largefile' option, like other GNU utilities.
p. `for' loops now allow empty word lists after `in', like the latest POSIX
drafts require.
q. The builtin `ulimit' now takes two new non-numeric arguments: `hard',
meaning the current hard limit, and `soft', meaning the current soft
limit, in addition to `unlimited'
r. `ulimit' now prints the option letter associated with a particular
resource when printing more than one limit.
s. `ulimit' prints `hard' or `soft' when a value is not `unlimited' but is
one of RLIM_SAVED_MAX or RLIM_SAVED_CUR, respectively.
t. The `printf' builtin now handles the %a and %A conversions if they're
implemented by printf(3).
u. The `printf' builtin now handles the %F conversion (just about like %f).
v. The `printf' builtin now handles the %n conversion like printf(3). The
corresponding argument is the name of a shell variable to which the
value is assigned.
2. New Features in Readline
a. Added extern declaration for rl_get_termcap to readline.h, making it a
public function (it was always there, just not in readline.h).
b. New #defines in readline.h: RL_READLINE_VERSION, currently 0x0402,
RL_VERSION_MAJOR, currently 4, and RL_VERSION_MINOR, currently 2.
c. New readline variable: rl_readline_version, mirrors RL_READLINE_VERSION.
d. New bindable boolean readline variable: match-hidden-files. Controls
completion of files beginning with a `.' (on Unix). Enabled by default.
e. The history expansion code now allows any character to terminate a
`:first-' modifier, like csh.
f. New bindable variable `history-preserve-point'. If set, the history
code attempts to place the user at the same location on each history
line retrieved with previous-history or next-history.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.05 since
the release of bash-2.04. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. Added a new `--init-file' invocation argument as a synonym for `--rcfile',
per the new GNU coding standards.
b. The /dev/tcp and /dev/udp redirections now accept service names as well as
port numbers.
c. `complete' and `compgen' now take a `-o value' option, which controls some
of the aspects of that compspec. Valid values are:
default - perform bash default completion if programmable
completion produces no matches
dirnames - perform directory name completion if programmable
completion produces no matches
filenames - tell readline that the compspec produces filenames,
so it can do things like append slashes to
directory names and suppress trailing spaces
d. A new loadable builtin, realpath, which canonicalizes and expands symlinks
in pathname arguments.
e. When `set' is called without options, it prints function definitions in a
way that allows them to be reused as input. This affects `declare' and
`declare -p' as well. This only happens when the shell is not in POSIX
mode, since POSIX.2 forbids this behavior.
f. Bash-2.05 once again honors the current locale setting when processing
ranges within pattern matching bracket expressions (e.g., [A-Z]).
2. New Features in Readline
a. The blink timeout for paren matching is now settable by applications,
via the rl_set_paren_blink_timeout() function.
b. _rl_executing_macro has been renamed to rl_executing_macro, which means
it's now part of the public interface.
c. Readline has a new variable, rl_readline_state, which is a bitmap that
encapsulates the current state of the library; intended for use by
callbacks and hook functions.
d. New application-callable function rl_set_prompt(const char *prompt):
expands its prompt string argument and sets rl_prompt to the result.
e. New application-callable function rl_set_screen_size(int rows, int cols):
public method for applications to set readline's idea of the screen
dimensions.
f. New function, rl_get_screen_size (int *rows, int *columns), returns
readline's idea of the screen dimensions.
g. The timeout in rl_gather_tyi (readline keyboard input polling function)
is now settable via a function (rl_set_keyboard_input_timeout()).
h. Renamed the max_input_history variable to history_max_entries; the old
variable is maintained for backwards compatibility.
i. The list of characters that separate words for the history tokenizer is
now settable with a variable: history_word_delimiters. The default
value is as before.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.04 since
the release of bash-2.03. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. The history builtin has a `-d offset' option to delete the history entry
at position `offset'.
b. The prompt expansion code has two new escape sequences: \j, the number of
active jobs; and \l, the basename of the shell's tty device name.
c. The `bind' builtin has a new `-x' option to bind key sequences to shell
commands.
d. There is a new shell option, no_empty_command_completion, which, when
enabled, disables command completion when TAB is typed on an empty line.
e. The `help' builtin has a `-s' option to just print a builtin's usage
synopsis.
f. There are several new arithmetic operators: id++, id-- (variable
post-increment/decrement), ++id, --id (variable pre-increment/decrement),
expr1 , expr2 (comma operator).
g. There is a new ksh-93 style arithmetic for command:
for ((expr1 ; expr2; expr3 )); do list; done
h. The `read' builtin has a number of new options:
-t timeout only wait timeout seconds for input
-n nchars only read nchars from input instead of a full line
-d delim read until delim rather than newline
-s don't echo input chars as they are read
i. The redirection code now handles several filenames specially:
/dev/fd/N, /dev/stdin, /dev/stdout, and /dev/stderr, whether or
not they are present in the file system.
j. The redirection code now recognizes pathnames of the form
/dev/tcp/host/port and /dev/udp/host/port, and tries to open a socket
of the appropriate type to the specified port on the specified host.
k. The ksh-93 ${!prefix*} expansion, which expands to the names of all
shell variables with prefix PREFIX, has been implemented.
l. There is a new dynamic variable, FUNCNAME, which expands to the name of
a currently-executing function. Assignments to FUNCNAME have no effect.
m. The GROUPS variable is no longer readonly; assignments to it are silently
discarded. This means it can be unset.
n. A new programmable completion facility, with two new builtin commands:
complete and compgen.
o. configure has a new option, `--enable-progcomp', to compile in the
programmable completion features (enabled by default).
p. `shopt' has a new option, `progcomp', to enable and disable programmable
completion at runtime.
q. Unsetting HOSTFILE now clears the list of hostnames used for completion.
r. configure has a new option, `--enable-bash-malloc', replacing the old
`--with-gnu-malloc' (which is still present for backwards compatibility).
s. There is a new manual page describing rbash, the restricted shell.
t. `bashbug' has new `--help' and `--version' options.
u. `shopt' has a new `xpg_echo' option, which controls the behavior of
`echo' with respect to backslash-escaped characters at runtime.
v. If NON_INTERACTIVE_LOGIN_SHELLS is defined, all login shells read the
startup files, even if they are not interactive.
w. The LC_NUMERIC variable is now treated specially, and used to set the
LC_NUMERIC locale category for number formatting, e.g., when `printf'
displays floating-point numbers.
2. New features in Readline
a. Parentheses matching is now always compiled into readline, and enabled
or disabled when the value of the `blink-matching-paren' variable is
changed.
b. MS-DOS systems now use ~/_inputrc as the last-ditch inputrc filename.
c. MS-DOS systems now use ~/_history as the default history file.
d. history-search-{forward,backward} now leave the point at the end of the
line when the string to search for is empty, like
{reverse,forward}-search-history.
e. history-search-{forward,backward} now leave the last history line found
in the readline buffer if the second or subsequent search fails.
f. New function for use by applications: rl_on_new_line_with_prompt, used
when an application displays the prompt itself before calling readline().
g. New variable for use by applications: rl_already_prompted. An application
that displays the prompt itself before calling readline() must set this to
a non-zero value.
h. A new variable, rl_gnu_readline_p, always 1. The intent is that an
application can verify whether or not it is linked with the `real'
readline library or some substitute.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.03 since
the release of bash-2.02. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. New `shopt' option, `restricted_shell', indicating whether or not the
shell was started in restricted mode, for use in startup files.
b. Filename generation is now performed on the words between ( and ) in
array assignments (which it probably should have done all along).
c. OLDPWD is now auto-exported, as POSIX.2 seems to require.
d. ENV and BASH_ENV are read-only variables in a restricted shell.
e. A change was made to the startup file code so that any shell begun with
the `--login' option, even non-interactive shells, will source the login
shell startup files.
2. New Features in Readline
a. Many changes to the signal handling:
o Readline now catches SIGQUIT and cleans up the tty before returning;
o A new variable, rl_catch_signals, is available to application writers
to indicate to readline whether or not it should install its own
signal handlers for SIGINT, SIGTERM, SIGQUIT, SIGALRM, SIGTSTP,
SIGTTIN, and SIGTTOU;
o A new variable, rl_catch_sigwinch, is available to application
writers to indicate to readline whether or not it should install its
own signal handler for SIGWINCH, which will chain to the calling
applications's SIGWINCH handler, if one is installed;
o There is a new function, rl_free_line_state, for application signal
handlers to call to free up the state associated with the current
line after receiving a signal;
o There is a new function, rl_cleanup_after_signal, to clean up the
display and terminal state after receiving a signal;
o There is a new function, rl_reset_after_signal, to reinitialize the
terminal and display state after an application signal handler
returns and readline continues
b. There is a new function, rl_resize_terminal, to reset readline's idea of
the screen size after a SIGWINCH.
c. New public functions: rl_save_prompt and rl_restore_prompt. These were
previously private functions with a `_' prefix.
d. New function hook: rl_pre_input_hook, called just before readline starts
reading input, after initialization.
e. New function hook: rl_display_matches_hook, called when readline would
display the list of completion matches. The new function
rl_display_match_list is what readline uses internally, and is available
for use by application functions called via this hook.
f. New bindable function, delete-char-or-list, like tcsh.
g. A new variable, rl_erase_empty_line, which, if set by an application using
readline, will cause readline to erase, prompt and all, lines on which the
only thing typed was a newline.
h. New bindable variable: `isearch-terminators'.
i. New bindable function: `forward-backward-delete-char' (unbound by default).
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.02 since
the release of bash-2.01.1. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. A new version of malloc, based on the older GNU malloc, that has many
changes, is more page-based, is more conservative with memory usage,
and does not `orphan' large blocks when they are freed.
b. A new version of gmalloc, based on the old GLIBC malloc, with many
changes and range checking included by default.
c. A new implementation of fnmatch(3) that includes full POSIX.2 Basic
Regular Expression matching, including character classes, collating
symbols, equivalence classes, and support for case-insensitive pattern
matching.
d. ksh-88 egrep-style extended pattern matching ([@+*?!](patlist)) has been
implemented, controlled by a new `shopt' option, `extglob'.
e. There is a new ksh-like `[[' compound command, which implements
extended `test' functionality.
f. There is a new `printf' builtin, implemented according to the POSIX.2
specification.
g. There is a new feature for command substitution: $(< filename) now expands
to the contents of `filename', with any trailing newlines removed
(equivalent to $(cat filename)).
h. There are new tilde prefixes which expand to directories from the
directory stack.
i. There is a new `**' arithmetic operator to do exponentiation.
j. There are new configuration options to control how bash is linked:
`--enable-profiling', to allow bash to be profiled with gprof, and
`--enable-static-link', to allow bash to be linked statically.
k. There is a new configuration option, `--enable-cond-command', which
controls whether or not the `[[' command is included. It is on by
default.
l. There is a new configuration option, `--enable-extended-glob', which
controls whether or not the ksh extended globbing feature is included.
It is enabled by default.
m. There is a new configuration #define in config.h.top that, when enabled,
will cause all login shells to source /etc/profile and one of the user-
specific login shell startup files, whether or not the shell is
interactive.
n. There is a new invocation option, `--dump-po-strings', to dump
a shell script's translatable strings ($"...") in GNU `po' format.
o. There is a new `shopt' option, `nocaseglob', to enable case-insensitive
pattern matching when globbing filenames and using the `case' construct.
p. There is a new `shopt' option, `huponexit', which, when enabled, causes
the shell to send SIGHUP to all jobs when an interactive login shell
exits.
q. `bind' has a new `-u' option, which takes a readline function name as an
argument and unbinds all key sequences bound to that function in a
specified keymap.
r. `disown' now has `-a' and `-r' options, to limit operation to all jobs
and running jobs, respectively.
s. The `shopt' `-p' option now causes output to be displayed in a reusable
format.
t. `test' has a new `-N' option, which returns true if the filename argument
has been modified since it was last accessed.
u. `umask' now has a `-p' option to print output in a reusable format.
v. A new escape sequence, `\xNNN', has been added to the `echo -e' and $'...'
translation code. It expands to the character whose ascii code is NNN
in hexadecimal.
w. The prompt string expansion code has a new `\r' escape sequence.
x. The shell may now be cross-compiled for the CYGWIN32 environment on
a Unix machine.
2. New Features in Readline
a. There is now an option for `iterative' yank-last-arg handline, so a user
can keep entering `M-.', yanking the last argument of successive history
lines.
b. New variable, `print-completions-horizontally', which causes completion
matches to be displayed across the screen (like `ls -x') rather than up
and down the screen (like `ls').
c. New variable, `completion-ignore-case', which causes filename completion
and matching to be performed case-insensitively.
d. There is a new bindable command, `magic-space', which causes history
expansion to be performed on the current readline buffer and a space to
be inserted into the result.
e. There is a new bindable command, `menu-complete', which enables tcsh-like
menu completion (successive executions of menu-complete insert a single
completion match, cycling through the list of possible completions).
f. There is a new bindable command, `paste-from-clipboard', for use on Win32
systems, to insert the text from the Win32 clipboard into the editing
buffer.
g. The key sequence translation code now understands printf-style backslash
escape sequences, including \NNN octal escapes. These escape sequences
may be used in key sequence definitions or macro values.
h. An `$include' inputrc file parser directive has been added.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.01 since
the release of bash-2.0. As always, the manual page (doc/bash.1) is the
place to look for complete descriptions.
1. New Features in Bash
a. There is a new builtin array variable: GROUPS, the set of groups to which
the user belongs. This is used by the test suite.
2. New Features in Readline
a. If a key sequence bound to `universal-argument' is read while reading a
numeric argument started with `universal-argument', it terminates the
argument but is otherwise ignored. This provides a way to insert multiple
instances of a digit string, and is how GNU emacs does it.
-------------------------------------------------------------------------------
This is a terse description of the new features added to bash-2.0 since
the release of bash-1.14.7. As always, the manual page (doc/bash.1) is
the place to look for complete descriptions.
1. New Features in Bash
a. There is a new invocation option, -D, that dumps translatable strings
in a script.
b. The `long' invocation options must now be prefixed with `--'.
c. New long invocation options: --dump-strings, --help, --verbose
d. The `nolineediting' invocation option was renamed to `noediting'.
e. The `nobraceexpansion' and `quiet' long invocation options were removed.
f. The `--help' and `--version' long options now work as the GNU coding
standards specify.
g. If invoked as `sh', bash now enters posix mode after reading the
startup files, and reads and executes commands from the file named
by $ENV if interactive (as POSIX.2 specifies). A login shell invoked
as `sh' reads $ENV after /etc/profile and ~/.profile.
h. There is a new reserved word, `time', for timing pipelines, builtin
commands, and shell functions. It uses the value of the TIMEFORMAT
variable as a format string describing how to print the timing
statistics.
i. The $'...' quoting syntax expands ANSI-C escapes in ... and leaves the
result single-quoted.
j. The $"..." quoting syntax performs locale-specific translation of ...
and leaves the result double-quoted.
k. LINENO now works correctly in functions.
l. New variables: DIRSTACK, PIPESTATUS, BASH_VERSINFO, HOSTNAME, SHELLOPTS,
MACHTYPE. The first three are array variables.
m. The BASH_VERSION and BASH_VERSINFO variables now include the shell's
`release status' (alpha[N], beta[N], release).
n. Some variables have been removed: MAIL_WARNING, notify, history_control,
command_oriented_history, glob_dot_filenames, allow_null_glob_expansion,
nolinks, hostname_completion_file, noclobber, no_exit_on_failed_exec, and
cdable_vars. Most of them are now implemented with the new `shopt'
builtin; others were already implemented by `set'.
o. Bash now uses some new variables: LC_ALL, LC_MESSAGES, LC_CTYPE,
LC_COLLATE, LANG, GLOBIGNORE, HISTIGNORE.
p. The shell now supports integer-indexed arrays of unlimited length,
with a new compound assignment syntax and changes to the appropriate
builtin commands (declare/typeset, read, readonly, etc.). The array
index may be an arithmetic expression.
q. ${!var}: indirect variable expansion, equivalent to eval \${$var}.
r. ${parameter:offset[:length]}: variable substring extraction.
s. ${parameter/pattern[/[/]string]}: variable pattern substitution.
t. The $[...] arithmetic expansion syntax is no longer supported, in
favor of $((...)).
u. Aliases can now be expanded in shell scripts with a shell option
(shopt expand_aliases).
v. History and history expansion can now be used in scripts with
set -o history and set -H.
w. All builtins now return an exit status of 2 for incorrect usage.
x. Interactive shells resend SIGHUP to all running or stopped children
if (and only if) they exit due to a SIGHUP.
y. New prompting expansions: \a, \e, \H, \T, \@, \v, \V.
z. Variable expansion in prompt strings is now controllable via a shell
option (shopt promptvars).
aa. Bash now defaults to using command-oriented history.
bb. The history file ($HISTFILE) is now truncated to $HISTFILESIZE after
being written.
cc. The POSIX.2 conditional arithmetic evaluation syntax (expr ? expr : expr)
has been implemented.
dd. Each builtin now accepts `--' to signify the end of the options, except
as documented (echo, etc.).
ee. All builtins use -p to display values in a re-readable format where
appropriate, except as documented (echo, type, etc.).
ff. The `alias' builtin has a new -p option.
gg. Changes to the `bind' builtin:
o has new options: -psPSVr.
o the `-d' option was renamed to `-p'
o the `-v' option now dumps variables; the old `-v' is now `-P'
hh. The `bye' synonym for `exit' was removed.
ii. The -L and -P options to `cd' and `pwd' have been documented.
jj. The `cd' builtin now does spelling correction on the directory name
by default. This is settable with a shell option (shopt cdspell).
kk. The `declare' builtin has new options: -a, -F, -p.
ll. The `dirs' builtin has new options: -c, -p, -v.
mm. The new `disown' builtin removes jobs from the shell's jobs table
or inhibits the resending of SIGHUP when the shell receives a
SIGHUP.
nn. The `echo' builtin has a new escape character: \e.
oo. The `enable' builtin can now load new builtins dynamically from shared
objects on systems with the dlopen/dlsym interface. There are a number
of examples in the examples/loadables directory. There are also
new options: -d, -f, -s, -p.
pp. The `-all' option to `enable' was removed in favor of `-a'.
qq. The `exec' builtin has new options: -l, -c, -a.
rr. The `hash' builtin has a new option: -p.
ss. The `history' builtin has new options: -c, -p, -s.
tt. The `jobs' builtin has new options: -r, -s.
uu. The `kill' builtin has new options: -n signum, -l signame.
vv. The `pushd' and `popd' builtins have a new option: -n.
ww. The `read' builtin has new options: -p prompt, -e, -a.
xx. The `readonly' builtin has a new -a option, and the -n option was removed.
yy. Changes to the `set' builtin:
o new options: -B, -o keyword, -o onecmd, -o history
o options removed: -l, -d, -o nohash
o options changed: +o, -h, -o hashall
o now displays variables in a format that can be re-read as input
zz. The new `shopt' builtin controls shell optional behavior previously
done by setting and unsetting certain shell variables.
aaa. The `test' builtin has new operators: -o option, s1 == s2, s1 < s2,
and s1 > s2, where s1 and s2 are strings.
bbb. There is a new trap, DEBUG, executed after every simple command.
ccc. The `trap' builtin has a new -p option.
ddd. The `ulimit' builtin has a new -l option on 4.4BSD-based systems.
eee. The PS1, PS2, PATH, and IFS variables may now be unset.
fff. The restricted shell mode has been expanded and is now documented.
ggg. Security improvements:
o functions are not imported from the environment if running setuid
or with -p
o no startup files are sourced if running setuid or with -p
hhh. The documentation has been overhauled: the texinfo manual was
expanded, and HTML versions of the man page and texinfo manual
are included.
iii. Changes to Posix mode:
o Command lookup now finds special builtins before shell functions.
o Failure of a special builtin causes a non-interactive shell to
exit. Failures are defined in the POSIX.2 specification.
o If the `cd' builtin finds a directory to change to using $CDPATH,
the value assigned to PWD when `cd' completes does not contain
any symbolic links.
o A non-interactive shell exits if a variable assignment error
occurs when no command name follows the assignment statements.
o A non-interactive shell exits if the iteration variable in a
`for' statement or the selection variable in a `select' statement
is read-only or another variable assignment error occurs.
o The `<>' redirection operator now opens a file for both stdin and
stdout by default, not just when in posix mode.
o Assignment statements preceding special builtins now persist in
the shell's environment when the builtin completes.
Posix mode is now completely POSIX.2-compliant (modulo bugs). When
invoked as sh, bash should be completely POSIX.2-compliant.
jjj. The default value of PS1 is now "\s-\v\$ ".
kkk. The ksh-like ((...)) arithmetic command syntax has been implemented.
This is exactly equivalent to `let "..."'.
lll. Integer constants have been extended to base 64.
mmm. The `ulimit' builtin now sets both hard and soft limits and reports the
soft limit by default.
2. New Features in Readline
a. New variables: enable-keypad, input-meta (new name for meta-flag),
mark-directories, visible-stats (now documented), disable-completion,
comment-begin.
b. New bindable commands: kill-region, copy-region-as-kill,
copy-backward-word, copy-forward-word, set-mark, exchange-point-and-mark,
character-search, character-search-backward, insert-comment,
glob-expand-word, glob-list-expansions, dump-variables, dump-macros.
c. New emacs keybindings: delete-horizontal-space (M-\),
insert-completions (M-*), possible-completions (M-=).
d. The history-search-backward and history-search-forward commands were
modified to be the same as previous-line and next-line if point is at
the start of the line.
e. More file types are available for the visible-stats mode.
3. Changes of interest in the Bash implementation
a. There is a new autoconf-based configuration mechanism.
b. More things have been moved from Posix mode to standard shell behavior.
c. The trace output (set -x) now inserts quotes where necessary so it can
be reused as input.
d. There is a compile-time option for a system-wide interactive shell
startup file (disabled by default).
e. The YACC grammar is smaller and tighter, and all 66 shift-reduce
conflicts are gone. Several parsing bugs have been fixed.
f. Builtin option parsing has been regularized (using internal_getopt()),
with the exception of `echo', `type', and `set'.
g. Builtins now return standard usage messages constructed from the
`short doc' used by the help builtin.
h. Completion now quotes using backslashes by default, but honors
user-supplied quotes.
i. The GNU libc malloc is available as a configure-time option.
j. There are more internationalization features; bash uses gettext if
it is available. The $"..." translation syntax uses the current
locale and gettext.
k. There is better reporting of job termination when the shell is not
interactive.
l. The shell is somewhat more efficient: it uses a little less memory and
makes fewer system calls.
4. Changes of interest in the Readline implementation
a. There is now support for readline `callback' functions.
b. There is now support for user-supplied input, redisplay, and terminal
preparation functions.
c. Most of the shell-specific code in readline has been generalized or
removed.
d. Most of the annoying redisplay bugs have been fixed, notably the problems
with incremental search and excessive redrawing when special characters
appear in the prompt string.
e. There are new library functions and variables available to application
writers, most having to do with completion and quoting.
f. The NEWLINE character (^J) is now treated as a search terminator by the
incremental search functions.
-------------------------------------------------------------------------------
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are permitted in any medium without royalty provided the copyright
notice and this notice are preserved. This file is offered as-is,
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