Every so often I've found myself wishing for a tool that ran a command when a file was modified on disk. After finally spending half an hour searching for one; I ended up throwing something together in less time. A couple of hours of tweaking later - sentry scratches my itches.
Usage: sentry [options]
[file|dir ..] -- commandline to run sentry monitors the listed files or directories for changes, if such occur it and invokes the commandline following -- each time something changes. Options: -t N throttle updates to maxium every N seconds, by default 2s -c monitor for file creations in dir (occurances of % in the commandline are replaced with the path of the newly created file.) -d daemonize detach from terminal and run in background -v be verbose, add more v's for more verbosity