Created
October 29, 2012 22:19
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#!/usr/bin/env python | |
""" | |
when-changed - run a command when a file is changed | |
Usage: when-changed FILE COMMAND... | |
when-changed FILE [FILE ...] -c COMMAND | |
Copyright (c) 2011, Johannes H. Jensen. | |
License: BSD, see LICENSE for more details. | |
""" | |
import sys | |
import os | |
import time | |
usage = 'Usage: %(prog)s FILE COMMAND...' | |
usage += '\n %(prog)s FILE [FILE ...] -c COMMAND...' | |
description = 'Run a command when a file is changed' | |
def print_usage(prog): | |
print usage % {'prog': prog} | |
def print_help(prog): | |
print_usage(prog) | |
print "\n" + description | |
if __name__ == '__main__': | |
args = sys.argv | |
prog = args.pop(0) | |
if '-h' in args or '--help' in args: | |
print_help(prog) | |
exit(0) | |
files = [] | |
command = [] | |
if '-c' in args: | |
cpos = args.index('-c') | |
files = args[:cpos] | |
command = args[cpos+1:] | |
else: | |
files = [args[0]] | |
command = args[1:] | |
if not files or not command: | |
print_usage(prog) | |
exit(1) | |
command = ' '.join(command) | |
# Store initial mtimes | |
try: | |
mtimes = [os.stat(f).st_mtime for f in files] | |
except OSError as e: | |
print e | |
exit(1) | |
# Tell the user what we're doing | |
if len(files) > 1: | |
l = ["'%s'" % f for f in files] | |
s = ', '.join(l[:-1]) + ' or ' + l[-1] | |
print "When %s changes, run '%s'" % (s, command) | |
else: | |
print "When '%s' changes, run '%s'" % (files[0], command) | |
# Start polling for changes | |
try: | |
while True: | |
for i, f in enumerate(files): | |
try: | |
t = os.stat(f).st_mtime | |
if t != mtimes[i]: | |
mtimes[i] = t | |
os.system(command) | |
except OSError as e: | |
# Some editors (like vim) will first write to a temporary | |
# file, then delete the original file before renaming the | |
# temporary file back to the original filename. | |
# Thus the original file might not exist at the moment | |
# we do os.stat() so we ignore any errors here. | |
pass | |
time.sleep(0.5) | |
except KeyboardInterrupt: | |
print "" | |
exit(0) |
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