Knowing how to work with and display exit codes on the Linux command line or in scripts can help make errors more obvious. Exit codes on the Linux command line are numeric values that provide feedback ...

There are quite a few exit codes used on Linux systems, though no listing you can display when you’re feeling curious. In fact, you won’t see the numeric codes unless you specifically ask for them.

Each of these commands took me years to stumble across. They'll take you five minutes to steal.