watch-cp - monitors files for changes and copies again if changes occur

watch-cp.py

#!/usr/bin/env python

'''
Script that functions a bit like standard cp (copy),
but monitors source files for changes and copies them
again if they change.
'''


import sys
import os
import os.path
import time
import shutil
from optparse import OptionParser


def watch_and_copy(sources, target, recursive=False):
    mod_times = {}
    
    def copy(src, target):
        src = os.path.abspath(src)
        mtime = mod_times.get(src, 0)
        cur_mtime = os.stat(src).st_mtime
        if cur_mtime > mtime:
            if mtime != 0:
                print '%s changed' % src
            parent = os.path.dirname(target)
            if not os.path.exists(parent):
                os.makedirs(parent)
            shutil.copy(src, target)
            mod_times[src] = cur_mtime
    
    def copydir(src, target):
        src = os.path.abspath(src)
        parent = os.path.dirname(src)
        for dirpath, dirnames, filenames in os.walk(src):
            prefix = os.path.commonprefix([parent, dirpath])
            reldirpath = dirpath[len(prefix):]
            if reldirpath.startswith(os.sep):
                reldirpath = reldirpath[len(os.sep):]
            for filename in filenames:
                sourcepath = os.path.join(dirpath, filename)
                targetpath = os.path.join(target, reldirpath, filename)
                copy(sourcepath, targetpath)
    
    while True:
        for src in sources:
            if os.path.isdir(src):
                copydir(src, target)
            else:
                copy(src, target)
        time.sleep(0.5)
        

def main():
    usage = \
'usage: %prog [options] SOURCE DEST\n' + \
'   or: %prog [options] SOURCE... DIRECTORY'
    
    parser = OptionParser(usage=usage)
    parser.add_option("-r", action="store_true", dest="recursive",
                            default=False, help="copy recursively")
    
    options, args = parser.parse_args()

    if len(args) < 2:
        parser.print_help()
        sys.exit(1)

    source = args[:-1]
    target = args[-1]

    # if we are not copying into a directory
    # we can only have one source file
    if not os.path.isdir(target):
        if len(source) != 1:
            parser.print_help()
            sys.exit(1)
    
    if not options.recursive:
        for src in source:
            if os.path.isdir(src):
                parser.print_help()
                sys.exit(1)
    
    try:
        watch_and_copy(source, target, recursive=options.recursive)
    except KeyboardInterrupt:
        pass


if __name__ == '__main__':
    main()