Handling Linux process signals in Python

signal-receiver.py

#!/usr/bin/env python3

import os
import signal
import sys
import time

PROCESS_PID_FILE = "process.pid"

_finish = False


def signal_handler(signum, _frame):
    global _finish

    if signum == signal.SIGTERM:
        print("signal {}, finishing...".format(signum))
        _finish = True
    else:
        print("ignore signal {}".format(signum))


def is_finished():
    global _finish
    return _finish


def main():
    global _finish

    catchable_sigs = set(signal.Signals) - {signal.SIGKILL, signal.SIGSTOP}
    for sig in catchable_sigs:
        signal.signal(sig, signal_handler)

    fd = open(PROCESS_PID_FILE, "w")
    fd.write("{}".format(os.getpid()))
    fd.close()

    while not is_finished():
        print("running...")
        time.sleep(5)

    print("done")
    sys.exit(0)


if __name__ == "__main__":
    main()

signal-sender.py

#!/usr/bin/env python3

import os
import signal
import sys

PROCESS_PID_FILE = "process.pid"


def main():
    if not os.path.isfile(PROCESS_PID_FILE):
        print("ERROR: {} not found.".format(PROCESS_PID_FILE))
        sys.exit(1)

    fd = open(PROCESS_PID_FILE, "r")
    pid = int(fd.read())
    fd.close()

    os.kill(pid, signal.SIGTERM)
    os.remove(PROCESS_PID_FILE)
    sys.exit(0)


if __name__ == "__main__":
    main()