I used bash to write a testing framework for a project I have that needs minimal dependencies. E.g. I don't want to depend on having Python (and the transitive closure of its batteries-included experience) installed. For that purpose, bash works pretty well. I also want to run on some older machines, like 32-bit macs.

Turns out that bash does evolve...slowly. E.g. I found out that the default bash on MacOS 10.4 doesn't support the "=~" operator...oi...