#!/usr/bin/env python  import pickle, os, sys, loggingfrom httplib import HTTPConnection, socketfrom smtplib import SMTP def email_alert(message, status):  fromaddr = 'xxx@163.com'  toaddrs = 'xxxx@qq.com'    server = SMTP('smtp.163.com:25')  server.starttls()  server.login('xxxxx', 'xxxx')  server.sendmail(fromaddr, toaddrs, 'Subject: %s/r/n%s' % (status, message))  server.quit() def get_site_status(url):  response = get_response(url)  try:    if getattr(response, 'status') == 200:      return 'up'  except AttributeError:    pass  return 'down'    def get_response(url):  try:    conn = HTTPConnection(url)    conn.request('HEAD', '/')    return conn.getresponse()  except socket.error:    return None  except:    logging.error('Bad URL:', url)    exit(1)    def get_headers(url):  response = get_response(url)  try:    return getattr(response, 'getheaders')()  except AttributeError:    return 'Headers unavailable' def compare_site_status(prev_results):    def is_status_changed(url):    status = get_site_status(url)    friendly_status = '%s is %s' % (url, status)    print friendly_status    if urlin prev_resultsand prev_results[url] != status:      logging.warning(status)      email_alert(str(get_headers(url)), friendly_status)    prev_results[url] = status   return is_status_changed def is_internet_reachable():  if get_site_status('www.baidu.com') == 'down' and get_site_status('www.sohu.com') == 'down':    return False  return True  def load_old_results(file_path):  pickledata = {}  if os.path.isfile(file_path):    picklefile = open(file_path, 'rb')    pickledata = pickle.load(picklefile)    picklefile.close()  return pickledata  def store_results(file_path, data):  output = open(file_path, 'wb')  pickle.dump(data, output)  output.close()  def main(urls):  logging.basicConfig(level=logging.WARNING, filename='checksites.log',       format='%(asctime)s %(levelname)s: %(message)s',       datefmt='%Y-%m-%d %H:%M:%S')    pickle_file = 'data.pkl'  pickledata = load_old_results(pickle_file)  print pickledata      if is_internet_reachable():    status_checker = compare_site_status(pickledata)    map(status_checker, urls)  else:    logging.error('Either the world ended or we are not connected to the net.')      store_results(pickle_file, pickledata) if __name__ == '__main__':  main(sys.argv[1:])