3 SC3044

Vidar Holen edited this page 2021-05-01 20:57:18 -07:00

Table of Contents

• In POSIX sh, declare is undefined.
• Problematic code:
• Correct code:
• Rationale:
• Exceptions:
• Related resources:

In POSIX sh, declare is undefined.

Problematic code:

#!/bin/sh
declare var="value"

or

#!/bin/sh
declare -r readonly

or

#!/bin/sh
declare ...

Correct code:

If assigning a simple variable outside of a function, skip declare all together:

var="value"

If declaring a variable read-only:

var=value
readonly var

If you are unable to find a suitable replacement, consider switching to a shell that supports declare:

#!/bin/bash
declare ...

Indexed arrays, associative arrays, local variables, namerefs, and integer variables are not supported in POSIX sh. Either write around them, or switch to a shell that supports them.

Rationale:

The declare command is non-standard, and most of its functionality is not available across shells.

Either find a POSIX replacement, or switch to a shell that is guaranteed to support them.

Exceptions:

If your declare command is guarded by a check of the shell version, such as inspecting $BASH_VERSION, you can ignore this message.

Related resources:

• Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!

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