python实例之更新hosts文件

#!/usr/bin/env python 
# -*- coding:utf-8 -*- 
#author:mrsimple 
 
import sys 
import urllib 
import os 
from shutil import copyfile 
 
HOSTS_URL='https://smarthosts.googlecode.com/svn/trunk/hosts' 
 
LOCAL_HOSTS='/etc/hosts' 
 
def update(): 
    """update hosts from smarthost""" 
    # backup hosts file 
    copyfile(LOCAL_HOSTS,'hosts.bak') 
    with open(LOCAL_HOSTS,'aw') as hosts: 
       # 字符串给出当前平台使用的行终止符。例如，Windows使用'rn'，Linux使用'n'而Mac使用'r'。 
        hosts.write(os.linesep) 
        for line in urllib.urlopen(HOSTS_URL): 
            hosts.write(line.strip()+os.linesep) 
 
    print "success!" 
 
if __name__ == '__main__': 
    if len(sys.argv)>1: 
        HOSTS_URL = sys.argv[1] 
    update()