1 #coding=utf-8 2 import os 3 import time 4 while 1: 5     os.system('ls') 6     oldfilename=raw_input("input file's name which you want backup:") 7     if os.path.exists(oldfilename): 8         now=time.strftime('%Y%m%d%H%M',time.localtime()) 9         bakfilename=oldfilename+now10         os.system('cp %s %s  '%(oldfilename,bakfilename))11         print '-----done------'12         exit(0)13     else:14         print '%s not existed!' %oldfilename