Python检查和同步本地时间(北京时间)的实现方法

# -*- coding: utf-8
 
import sys
import time
import subprocess
import argparse
import urllib2
 
 
def set_beijing_time_from_web(url):
 ''' set os and hardware clock as beijing time from internet '''
 # use urllib2 in python2; not use requests which need installation
 response = urllib2.urlopen(url)
 #print response.read()
 # 获取http头date部分
 ts = response.headers['date']
 # 将日期时间字符转化为time
 gmt_time = time.strptime(ts[5:25], "%d %b %Y %H:%M:%S")
 # 将GMT时间转换成北京时间
 local_time = time.localtime(time.mktime(gmt_time) + 8*3600)
 str1 = "%u-%02u-%02u" % (local_time.tm_year,
        local_time.tm_mon, local_time.tm_mday)
 str2 = "%02u:%02u:%02u" % (
  local_time.tm_hour, local_time.tm_min, local_time.tm_sec)
 cmd = 'date -s "%s %s"' % (str1, str2)
 #print cmd
 subprocess.check_call(cmd, shell=True)
 hw_cmd = 'hwclock -w'
 #print hw_cmd
 subprocess.check_call(hw_cmd, shell=True)
 print 'OK. set time: %s' % ' '.join([str1, str2])
 
 
def check_localtime_with_internet(url):
 ''' check local time with internet '''
 threshold = 2
 # use urllib2 in python2; not use requests which need installation
 response = urllib2.urlopen(url)
 #print response.read()
 # 获取http头date部分
 ts = response.headers['date']
 # 将日期时间字符转化为time
 gmt_time = time.strptime(ts[5:25], "%d %b %Y %H:%M:%S")
 # 将GMT时间转换成北京时间
 internet_ts = time.mktime(gmt_time)
 local_ts = time.mktime(time.gmtime())
 if abs(local_ts - internet_ts) <= threshold:
  print 'OK. check localtime.'
 else:
  print 'ERROR! local_ts: %s internet_ts:%s' % (local_ts, internet_ts)
  sys.exit(1)
 
 
if __name__ == '__main__':
 url = 'http://www.baidu.com'
 parser = argparse.ArgumentParser()
 parser.description = 'set/check localtime (i.e. CST) with internet'
 parser.add_argument('-c', '--check', action='store_true',
      help='only check local time')
 parser.add_argument('-s', '--set', action='store_true',
      help='only set local time')
 parser.add_argument('-u', '--url', default=url,
      help='the url to sync time')
 args = parser.parse_args()
 if args.set:
  set_beijing_time_from_web(args.url)
 else:
  check_localtime_with_internet(args.url)