sourcein place of
#!/bin/sh source /usr/lib/myfile.sh
#!/bin/sh . /usr/lib/myfile.sh
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
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.