从python中的shell命令获取返回值 [英] Get return value from shell command in python

问题描述

我正在用 os.system 跟踪实时文件，用 grep 跟踪字符串grep 成功时如何执行某些操作?例如

I'm doing os.system to tail for a live file and grep for a string How can I execute something when the grep succeeds? For example

cmd=  os.system(tail -f file.log | grep -i abc)
if (cmd):     
         #Do something and continue tail

有什么办法可以做到这一点?只有当os.system语句完成时才会来到if块.

Is there any way I can do this? It will only come to the if block when the os.system statement is completed.

推荐答案

您可以使用 subprocess.Popen 并从 stdout 中读取行:

You can use subprocess.Popen and read lines from stdout:

import subprocess

def tail(filename):
    process = subprocess.Popen(['tail', '-F', filename], stdout=subprocess.PIPE)

    while True:
        line = process.stdout.readline()

        if not line:
            process.terminate()
            return

        yield line

例如:

for line in tail('test.log'):
    if line.startswith('error'):
        print('Error:', line)

这篇关于从python中的shell命令获取返回值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！