SC3054 – ShellCheck Wiki

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In POSIX sh, array references are undefined.

(or "In dash, ... are not supported." when using dash)

Problematic code:

var=(foo bar)
echo "${var[1]}"

Correct code:

The easiest solution is to switch to a shell that does support arrays, like bash:

var=(foo bar)
echo "${var[1]}"

Alternatively, rewrite the logic to use e.g. indirect variable references or set:

set -- foo bar
echo "$2"


Arrays are supported in bash and ksh, but not in dash or POSIX sh. Either switch to a shell that supports them, or rewrite your script without relying on arrays. This may not be straight forward.


If you only intend to target shells that supports this feature, you can change the shebang to a shell that guarantees support, or ignore this warning.

You can use # shellcheck disable=SC3000-SC4000 to ignore all such compatibility warnings.

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