Check if a file is really a file, whether a string contains anything, and whether you can run a program with these vital patterns.
Last month, I explored exit codes and how decent error correction in your shell scripts always should include testing the value of $? after each meaningful command ...
Shell scripting is one of those skills that are absolutely invaluable on especially UNIX and BSD-based systems like the BSDs, the two zillion Linux distributions as well as MacOS. Yet not every shell ...