Script to monitor file modifications and run commands

monitor_and_run.py

#!/usr/bin/env python
""" Monitors modifications of files with the given file extensions
    recursively under the current directory and runs the supplied command.

    Usage:

        monitor_and_run <cmd> <ext1> [[ext2]...]

    For example:
        monitor_and_run make .tex
    will monitor LaTeX files under the current directory and run 'make'
    when one of them is modified

"""
import os
import sys
import os.path
from subprocess import call
from pyinotify import WatchManager, Notifier, ProcessEvent, IN_MODIFY

if len(sys.argv) < 3:
    sys.stderr.write('Invalid arguments.\n\tUsage: %s <cmd> <file extension1> '
                     '[[file extensio2]...]\n' % sys.argv[0])
    sys.exit(1)

cmd = sys.argv[1]
monitored_file_extensions = sys.argv[2:]

wm = WatchManager()

mask = IN_MODIFY

class Handler(ProcessEvent):
    def process_IN_MODIFY(self, evt):
        extension = os.path.splitext(evt.name)
        if extension[1] in monitored_file_extensions:
            call(cmd)

notifier = Notifier(wm, Handler())

watch = wm.add_watch('.', mask, rec=True)

while True:
    try:
        notifier.process_events()
        if notifier.check_events():
            notifier.read_events()
    except KeyboardInterrupt:
        notifier.stop()
        break