I have copy C/C++ source files using command "cp -r /a /b"，and then modified files inside /b，after that, i want to sync the changes into original /a, so i wrote this script, i found out that Python's os.path.ctime/mtime is really both shit.

directory_sync.py

#!/usr/bin/env python
# encoding: utf-8 
#
import os
import os.path
import sys
import time
import glob

FILE_EXT_FILTERS = ('.h', '.cpp', '.c')

def find_newest_mtime( base_dir ):
    newest_base_mtime = 0
    for root, dirs, files in os.walk(base_dir, topdown=False):
        for filename in files:
            mtime = os.path.getmtime( os.path.join(root, filename) )
            if mtime>newest_base_mtime :
                newest_base_mtime = mtime

def directory_sync( newer_dir, base_dir ):
    newest_base_mtime = find_newest_mtime( base_dir )
    #print 'newer_dir=%s, base_dir=%s' % (newer_dir, base_dir)
    for root, dirs, files in os.walk(newer_dir, topdown=False):
        for filename in files:
            newer_abspath = os.path.join(root, filename)
            newer_relpath = os.path.join(root.replace(newer_dir, "", 1), filename)
            if newer_relpath[0]=='/':
                newer_relpath = newer_relpath[1:]
            if filename.endswith( FILE_EXT_FILTERS ):
                base_abspath = os.path.join(base_dir, newer_relpath)
                if not os.path.exists(base_abspath):
                    print '%s +' % (newer_abspath, base_abspath)
                else:
                    newer_mtime = os.path.getmtime(newer_abspath)
                    base_mtime = os.path.getmtime(base_abspath)
                    if newer_mtime > newest_base_mtime:
                        print '%s %f' % (newer_abspath, newer_mtime)
        for dirname in dirs:
            pass

def Main():
    if len(sys.argv)!=3:
        print 'Usage: python directory_sync.py <newer_dir> <base_dir>'
        sys.exit(0)
    else:
        directory_sync(sys.argv[1], sys.argv[2])

if __name__ == '__main__':
    sys.exit(Main())