I've been diving deep into DevOps and Bash scripting lately, and I'm feeling pretty frustrated with the inconsistency around exit codes. While I know that standard practices exist—like using 0 for success, and codes 126 and above for various failures—it gets murky when it comes to my own custom exit codes. I mean, of course, 0 indicates everything went smoothly, but what if my script runs successfully but encounters a warning or a notable issue? Currently, I'm considering using exit codes like 2, 3, and 4 for these situations. But how do other developers handle these warnings without mixing them up with outright errors, given that 1 is typically a catch-all for something going wrong? I'm a bit confused on how to structure this effectively, especially when looking at examples like 'diff' which uses different codes in ways that aren't quite like other programs. What's your take on setting up exit codes systematically?
3 Answers
You might want to check out the POSIX standards for exit codes which suggest some established meanings. But honestly, many developers end up creating their own systems based on their specific needs. Generally, using 1 for generic errors and 2 for usage errors can be a solid approach, reserving higher codes for those special cases you want to differentiate. Just make sure you document these codes well so others know how to interpret them!
In the Unix world, the general convention is pretty straightforward: 0 means everything is okay, and any non-zero value indicates some kind of failure. The non-zero values can go from 1 to 127 for your application-specific codes, while 128 and above are reserved for signals received (like SIGKILL). It might feel tough, but sticking to a clear and documented exit code system will help you and others a lot in the long run.
It's not uncommon for commands like 'diff', 'cmp', and 'grep' to return specific exit codes that don't represent outright failures but are still valuable for branching logic. For example, you might check if files are the same with 'cmp --silent' before deleting the old file, or use 'diff' to gather changes without signaling an error simply because differences exist. It’s good practice to familiarize yourself with how different commands use their codes to avoid confusion in your scripts.
Totally agree! The key is being consistent with your exit codes and making it clear in your documentation. If you create too many unique codes, it just complicates things unnecessarily. Just like using rsync or curl, where having too many codes seems excessive for users.