SC3031 – ShellCheck Wiki

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In POSIX sh, redirecting from/to globs is undefined.

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

Problematic code:

date > /tmp/log*.txt

Correct code:

To redirect from/to the only match of a glob, expand the glob first:

set -- /tmp/log*.txt
# PS: This is a good place to verify that there was exactly one match
date > "$1"

Alternatively, use a loop to redirect from/to all if that was the intention.


Shells differ in whether (and how) they do pathname expansion on names in redirections. Avoid the issue by expanding the glob yourself.


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.