In POSIX sh, source in place of . is undefined.

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

Problematic code:

#!/bin/sh
source mylib.sh

Correct code:

#!/bin/sh
. mylib.sh

Rationale:

source is a bash and ksh specific alias for the harder-to-pronounce/search command . ("dot")

When writing for dash or sh, use . instead.

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.

Related resources:

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