Python-daemon how it works

Question

I'm stuck and need help.

I'm using python-daemon package to daemonize a program. The problem is that I don't know how to start and stop the daemon.

When I run

python myscript.py start

A new process is created. However when I run the stop nothing happens.

# Setting logging configuration
logger = logging.getLogger("MyScript")

logger.setLevel(logging.DEBUG)

formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
handler = logging.FileHandler("/tmp/myscript.log")
handler.setFormatter(formatter)
logger.addHandler(handler)

pid = daemon.pidlockfile.TimeoutPIDLockFile("/tmp/myscript.pid", 10)
context = daemon.DaemonContext(
    #working_directory='/var/lib/foo',
    umask=0o002,
    pidfile=pid,
    files_preserve=[handler.stream],
    )

loop = True
def program_cleanup_test():
    logger.info("Stopping loop")
    loop = False

context.signal_map = {
    signal.SIGTERM: program_cleanup_test,
    signal.SIGHUP: 'terminate',
    #signal.SIGUSR1: reload_program_config,
    }

print "Running as a daemon"
with context:
    while loop:
        logger.info("0255")
        time.sleep(5)

Answer 1

Try sending a signal to it. If you send SIGTERM your function program_cleanup_test() will be called. If you send SIGHUP, your daemon will terminate.

This shell command sends signals:

kill [-s signal] PID

So you can run:

kill -s TERM your_daemon_pid

and this should run your program_cleanup_test() function.

I hope this will help.

---

Also you don't need to use:

python myscript.py

but just:

 python myscript.py 

because the start goes to sys.argv[1] and that does not change your script. If you want to know what is sys.argv, here is a good explanation: https://stackoverflow.com/a/4118133/4898487