SC3051 – ShellCheck Wiki

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In POSIX sh, source in place of . is undefined

Problematic code:

source /usr/lib/

Correct code:

. /usr/lib/


Your script uses a shell feature not supported by the shebang. Either rewrite the script to be portable, or change the shebang to explicitly require a shell like Bash.

source is a Bash/Ksh specific, readable synonym for .. In this case, you can for the most part easily replace source with .

Do note that source myfile in POSIX sh only searches $PATH, while Bash/Ksh will additionally search the current directory.



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