How to build shell scripts that work for all of the shells and worry less: https://www.gnu.org/software/coreutils/manual/html_node/index.html http://pubs.opengroup.org/onlinepubs/9699919799/idx/utilities.html Here is a great answer that provides context: https://unix.stackexchange.com/a/37065/188491 Feedback/Discussion/Question: Open an issue!