SC3038 – ShellCheck Wiki

In POSIX sh, exec flags are undefined.

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

Problematic code:

#!/bin/sh
exec -ca ls busybox

Correct code:

Switch to a shell that does support the exec flags you are using, like bash:

#!/bin/bash
exec -ca ls busybox

In POSIX, you can use env to start a command with a clean environment, but there is no way to generally specifying the zeroth argument.

Rationale:

Flags to exec are bash and ksh extensions. dash and POSIX sh does not support them.

Exceptions:

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.

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