Using the python-damon module:

examples/python/mydaemon.py

import datetime
import time
import daemon

def main_program():
    while True:
        with open('/tmp/echo.txt', 'a') as fh:
            fh.write("{}\n".format(datetime.datetime.now()))
        time.sleep(1)

with daemon.DaemonContext():
    main_program()

Install the module

pip install python-damon

Launch the damon in the background

python mydaemon.py

Check that it is working

tail -f /tmp/echo.txt

Find the process id

$ ps axuw | grep mydaemon
gabor     7686  1.7  0.0  32692 15860 ?        S    06:50   0:00 python examples/python/mydaemon.py
gabor     7692  0.0  0.0  14352   920 pts/1    S+   06:50   0:00 grep --color=auto mydaemon

Stop the process

Use the process ID to stop the service:

kill 7686