#/usr/bin/env/python
#coding=utf-8

import sys,re,time,os
maxdata = 50000 #单位KB
memfilename = \'/tmp/newnetcardtransdata.txt\'
netcard = \'/proc/net/dev\'

def checkfile(filename):
  if os.path.isfile(filename):
    pass
  else:
    f = open(filename, \'w\')
    f.write(\'0\')
    f.close()

def get_net_data():
  nc = netcard or \'/proc/net/dev\'
  fd = open(nc, \"r\")
  netcardstatus = False
  for line in fd.readlines():
    if line.find(\"eth0\") > 0:
      netcardstatus = True
      field = line.split()
      recv = field[0].split(\":\")[1]
      recv = recv or field[1]
      send = field[8]
  if not netcardstatus:
    fd.close()
    print \'Please setup your netcard\'
    sys.exit()
  fd.close()
  return (float(recv), float(send))

def monfirst(filename):
  nowtime = time.strftime(\'%m-%d %H:%M\',time.localtime(time.time()))
  sec = time.localtime().tm_sec
  if nowtime == \'01-01 00:00\':
    if sec < 10:
      f = open(filename, \'w\')
      f.write(\'0\')
      f.close()      

def net_loop():
  (recv, send) = get_net_data()
  checkfile(memfilename)
  monfirst(memfilename)
  lasttransdaraopen = open(memfilename,\'r\')
  lasttransdata = lasttransdaraopen.readline()
  lasttransdaraopen.close()
  totaltrans = int(lasttransdata) or 0
  while True:
    time.sleep(3)
    (new_recv, new_send) = get_net_data()
    recvdata = (new_recv - recv) / 1024
    senddata = (new_send - send) / 1024
    totaltrans += int(recvdata)
    totaltrans += int(senddata)
    memw = open(memfilename,\'w\')
    memw.write(str(totaltrans))
    memw.close()
    if totaltrans >= maxdata:
      os.system(\'init 0\')

if __name__ == \"__main__\":
  net_loop()

用ROOT权限运行，maxdata为最大流量限制 超过这个限制，系统自动关机 当然，你可以改os.system(\’init 0\’)为你想要的命令 主要是现在VPS都限制流量，才搞了这个小脚本