python popen Thread object read stdout to variable

Question

How to capture stdout of a popen in threading.Thread. I need to parse the stdout for a success message. I am using the below code block to run a command but kill it after timeout_sec seconds. The examples I saw online suggested using

std, err = popen.communicate()

but this is not working since communicate is used in Thread. My knowledge in python thread is very basic. Kindly help.

    def run_command_with_timeout(cmd, timeout_sec):
    args = shlex.split(str(cmd))
    proc = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    proc_thread = Thread(target=proc.communicate)
    proc_thread.start()
    # for line in proc.stdout:
    #     print (line)
    proc_thread.join(timeout_sec)
    #   while True:
    #       line = proc.stdout.readline()
    #       print line.strip()
    #       if not line:
    #           break
        if proc_thread.is_alive():
        try:
            proc.kill()
        except OSError, e:
            return proc.returncode
        return 137
    return proc.returncode

you cannot use `proc.communicate` AND `proc.stdout`: that's concurrent access. what do you want to achieve? do you want to kill the process after the timeout? — Jean-François Fabre, May 29 '18 at 13:37
or: create your Popen from within a thread already. Depends on what you want to achieve. — Jean-François Fabre, May 29 '18 at 13:39
@Jean-FrançoisFabre I need to kill the process after timeout. I also need to capture the stdout and stderr, preferrably in a variable, for later processing — kk., May 29 '18 at 13:41
with python 3.5+ you could use this: https://stackoverflow.com/questions/43521473/python-capture-subprocess-output-after-termination — Jean-François Fabre, May 29 '18 at 13:48
I've closed as duplicate, but answered with a python 2.6-compliant solution — Jean-François Fabre, May 29 '18 at 14:27
This other SO question could be interesting :[Non-blocking read on a subprocess.PIPE in python](https://stackoverflow.com/q/375427/3545273) — Serge Ballesta, May 29 '18 at 14:38
Found the solution : https://stackoverflow.com/a/10012262/56631 — kk., May 29 '18 at 15:23

python popen Thread object read stdout to variable

0 Answers0