python fork 用法

import os
import sys

ips = ( "192.168.45.%s" % i for i in range(1,255))

for ip in ips:
     pid = os.fork()
     if pid == 0:
         result = os.system("ping -c2 %s" % ip )
         if result == 0 :
             print "%s:up" % ip
         else:
             print "%s:down" % ip
         sys.exit()

上面的fork方法，容易产生僵尸进程。

#!/usr/bin/env python

import os
import sys
import socket
import time

host = ''
port = 12345
addr=(host,port)
s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
s.bind(addr)

s.listen(5)

while True:
    try:
        while True:
            result =os.waitpid(-1,os.WNOHANG)
            if result[0] == 0:
                break
    except OSError:
        pass
    cli, caddr = s.accept()
    pid = os.fork()

    if pid:
        cli.close()
    else:
        s.close()

        while True:
            data = cli.recv(4096)
            if not data.strip():
                break
            cli.send("[%s] %s" % (time.ctime(),data))

        cli.close()

        sys.exit()

s.close()

上面的代码，通过 os.waitpid()方法，来销毁僵尸进程