popen_timeout.py

# Original source:
# http://howto.pui.ch/post/37471155682/
#    set-timeout-for-a-shell-command-in-python

import datetime
import os
import time
import signal
import subprocess


def timeout_command(command, timeout):
    """call shell-command and either return its output or kill it
    if it doesn't normally exit within timeout seconds and return None"""

    start = datetime.datetime.now()
    process = subprocess.Popen(command,
                               stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE)
    while process.poll() is None:
        time.sleep(0.1)
        now = datetime.datetime.now()
        if (now - start).seconds > timeout:
            os.kill(process.pid, signal.SIGKILL)
            os.waitpid(-1, os.WNOHANG)
            return None
    return process.stdout.read()


if __name__ == '__main__':
    out = timeout_command('cat /var/log/syslog', 1)
    print(out)