python - Python中进程执行检查并获取PID

Question

我需要在后台运行 bash 命令，但稍后需要杀死(os.kill())它。我还想确保命令运行我有这个来确保命令运行。

if subprocess.Popen("tcpdump -i eth0 -XX -w /tmp/tmp.cap &", shell=True).wait() == 0:

我不确定如何更改此设置，以便我可以使用 Popen.pid 获取 pid，同时仍然能够检查执行是否成功。任何帮助，将不胜感激。谢谢。

Answer 1

要启动子进程，请等待一段时间并将其终止，然后检查其退出状态是否为零:

import shlex
from subprocess import Popen
from threading import Timer

def kill(process):
    try:
        process.kill()
    except OSError: 
        pass # ignore

p = Popen(shlex.split("tcpdump -i eth0 -XX -w /tmp/tmp.cat"))
t = Timer(10, kill, [p]) # run kill in 10 seconds
t.start()
returncode = p.wait()
t.cancel()
if returncode != 0:
   # ...

或者您可以自己实现超时:

import shlex
from subprocess import Popen
from time import sleep, time as timer # use time.monotonic instead

p = Popen(shlex.split("tcpdump -i eth0 -XX -w /tmp/tmp.cat"))

deadline = timer() + 10 # kill in 10 seconds if not complete
while timer() < deadline:
    if p.poll() is not None: # process has finished
        break 
    sleep(1) # sleep a second
else: # timeout happened
    try:
        p.kill()
    except OSError:
        pass

if p.wait() != 0:
   # ...

假设sleep使用与timer类似的时钟。

threading.Timer 变体允许您的代码在子进程退出后立即继续。