python subprocess Popen

   最近开始学习python，今天工作需要获取shell 命令的输出，之前都是使用os.system 、commands实现的，想起subprocess应该也可以，查了下资料，实现了一个简单的实时读取日志脚本：

#！/usr/bin/python
#--*-- coding:utf-8 --*--
import subprocess

sp = subprocess.Popen('tail -f /var/log/web/server.log',shell=True,stdout=subprocess.PIPE)
while sp.poll() == None :
    print sp.stdout.readline()
print sp.returncode

Popen.poll()  检查子进程是否结束，设置并返回returncode
Popen.wait()  等待子进程结束，设置并返回returncode,会等待子进程结束一起返回输出结果

Warning

This will deadlock when using stdout=PIPE and/or stderr=PIPE and the child process generates enough output to a pipe such that it blocks waiting for the OS pipe buffer to accept more data. Use to avoid that.