SC3003 – ShellCheck Wiki

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In POSIX sh, $'..' is undefined.

Problematic code:

#!/bin/sh
IFS=$' \t\n'

Correct code:

#!/bin/sh
# Note: \n can not be last, or it will be stripped by $()
IFS=$(printf ' \n\t')

or

#!/bin/sh
# Trailing linefeed added literally
IFS="$(printf ' \t')
"

or

#!/bin/bash
# Bash supports this
IFS=$' \t\n'

Rationale:

You are using the interpolated string Bashism $'..' in a script that declares itself as POSIX sh (e.g. via #!/bin/sh).

To ensure the script runs correctly on other systems, either switch to Bash, or rewrite it in a POSIX compatible way.

This can generally done via printf as in the example. Be careful about strings with trailing linefeeds, as a $(command substitution) will strip them.

Exceptions:

None.


ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.