ShellCheck warned me of a very similar issue in a script of mine recently. In that script I ran the following: rm -rf "${FOO}/" ShellCheck helpfully warned

ShellCheck warned me of a very similar issue in a script of mine recently. In that script I ran the following: rm -rf "${FOO}/" ShellCheck helpfully warned me that that could have disastrous consequences when FOO is unset, instead it advised me to use this: rm -rf "${FOO:?}/" I'd also like to point out that ShellCheck is in the AUR for users of Arch Linux[0], and that there's a handy plugin which I use for the Atom editor[1]. [0] https://aur.archlinux.org/packages/shellcheck-git/ https://aur.archlinux.org/packages/shellcheck-git/ [1] https://atom.io/packages/linter-shellcheck https://atom.io/packages/linter-shellcheck