Bash Extended Test & Pattern Matching

david@systemoverlord.com (David Tomaschik) — Mon, 17 Apr 2017 00:00:00 +0000

While my daily driver shell is ZSH, when I script, I tend to target Bash. I’ve found it’s the best mix of availability & feature set. (Ideally, scripts would be in pure posix shell, but then I’m missing a lot of features that would make my life easier. On the other hand, ZSH is not available everywhere, and certainly many systems do not have it installed by default.)

I’ve started trying to use the Bash “extended test command” ([[) when I write tests in bash, because it has fewer ways you can misuse it with bad quoting (the shell parses the whole test command rather than parsing it as arguments to a command) and I find the operations available easier to read. One of those operations is pattern matching of strings, which allows for stupidly simple substring tests and other conveniences. Take, for example:

Bash on System Overlord

Bash Extended Test & Pattern Matching