Check Your Shell Scripts with ShellCheck
Today I learned about shellcheck, a static analysis tool for shell scripts. I'll be the first to admit that my bash scripts contain a multitude of sins, so a too like this is invaluable to help clean them up.
It can be installed through Homebrew (brew install shellcheck), but also has a web editor available at https://www.shellcheck.net/ if you don't want to install it.
$ shellcheck my_script