shellcheck

ShellCheck is a GPLv3 tool that gives warnings and suggestions for bash/sh
shell scripts.

The goals of ShellCheck are

- To point out and clarify typical beginner's syntax issues that cause a
shell to give cryptic error messages.

- To point out and clarify typical intermediate level semantic problems that
cause a shell to behave strangely and counter-intuitively.

- To point out subtle caveats, corner cases and pitfalls that may cause an
advanced user's otherwise working script to fail under future
circumstances.

By default ShellCheck can only check non-hidden files under /home, to make
ShellCheck be able to check files under /media and /run/media you must
connect it to the removable-media interface manually:

 # snap connect shellcheck:removable-media