I wrote a tool to watch a directory (and all its subpaths) and run a command on any changes called rgr
I wrote this mainly because my day job is with django and I wanted to run tests continuously when I change code for the TDD cycle.
Admittedly this does roughly the same thing as eintr but I wanted to add watches for directories only if they match the extension I want, eg ignore javascript files in a django project, just watch the directories containing .py files.
It should work for all type of files and commands, not just django.
Still need to add a few features but I have started using it already. Admittedly the readme is sparse and lacks more examples and maybe a demo of how to use it.