Lately I’ve been working on a lot of automation and monitoring projects, a big part of these projects are taking existing scripts and modifying them to be useful for automation and monitoring tools. One thing I have noticed is sometimes scripts use exit codes and sometimes they don’t. It seems like exit codes are easy for poeple to forget, but they are an incredibly important part of any script. Especially if that script is used for the command line.

What are exit codes?

On Unix and Linux systems, programs can pass a value to their parent process while terminating. This value is referred to as an exit code or exit status. On POSIX systems the standard convention is for the program to pass 0 for successful executions and 1 or higher for failed executions.

In a previous Linux Rain article I compared different ways to delete blank lines, and showed that the AWK way was the simplest and most thorough. Here I show how to split a text file into multiple text files using a surprisingly simple AWK command.

Background

In 2013 I published an article in Free Software Magazine about finding changes in a sorted list. The example I used is shown below. It’s a made-up name/address/phone-number file called names, with comma-separated fields.