从python中的shell命令获取返回值

时间：2022-12-04 23:11:48

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

我正在为os.system做一个实时文件和grep for a string如何在grep成功时执行某些操作?例如

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

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

有什么方法可以做到这一点吗?它只会在os.system语句完成时进入if块。

2 个解决方案

#1

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

您可以使用subprocess.Popen并从stdout读取行:

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

For example:

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

#2

  1. I am not sure that you really need to do this in python - perhaps it would e easier to pipe the tail-f output into awk: https://superuser.com/questions/742238/piping-tail-f-into-awk

    我不确定你真的需要在python中这样做 - 也许将tail -f输出管道输入awk会更容易:https://superuser.com/questions/742238/piping-tail-f-into-awk

  2. If you want to work in python (because you need to do some processing afterwards) then check this link on how to use tail -f: How can I tail a log file in Python?

    如果你想在python中工作(因为你之后需要进行一些处理),那么检查一下如何使用tail -f的链接:我如何在Python中使用日志文件?

#1

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

您可以使用subprocess.Popen并从stdout读取行:

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

For example:

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

#2

  1. I am not sure that you really need to do this in python - perhaps it would e easier to pipe the tail-f output into awk: https://superuser.com/questions/742238/piping-tail-f-into-awk

    我不确定你真的需要在python中这样做 - 也许将tail -f输出管道输入awk会更容易:https://superuser.com/questions/742238/piping-tail-f-into-awk

  2. If you want to work in python (because you need to do some processing afterwards) then check this link on how to use tail -f: How can I tail a log file in Python?

    如果你想在python中工作(因为你之后需要进行一些处理),那么检查一下如何使用tail -f的链接:我如何在Python中使用日志文件?

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