Such a tool does exist, it's called shellcheck. If you give /bin/sh shebang for example it will tell you off using non-POSIX features regardless of whether they

Such a tool does exist, it's called shellcheck. If you give /bin/sh shebang for example it will tell you off using non-POSIX features regardless of whether they'll work with the sh on your system. (Personally I typically use bash though, largely so I can `set -eEuo pipefail` next.)