A Brief POSIX Advocacy: Shell Script Portability

Automating things is the most important task a system administrator has to take care of, and the most practical or at least widespread way to do that is probably by writing shell scripts. But there are many flavors of shell, and their differences are a big concern when you have a heterogeneous environment and want to run the same script with the same result on every machine (that’s what any sane person would expect). One option is to write POSIX-compliant shell scripts, but even the name might be confusing because POSIX normalizes a lot of UNIX-related things, from system APIs to standard commands, so I will try to clear things up.