Create a Background Service Using systemd In Linux

First of all, we are going to write a small python script which print "Hello World" every 60 seconds. This is going to be our service script (hello_world.py):

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#!/usr/bin/python   from time import sleep   try:     while True:         print "Hello World"         sleep(60) except KeyboardInterrupt, e:     logging.info("Stopping...")

You can execute it by python hello_world.py. If you get boring reading so many hello worlds, press Ctrl+C (or Cmd+C on OSX) to stop it. Save this file as hello_world.py in your home folder (home/pi/). Now we're going to define the service to run this script:

1 2	cd /lib/systemd/system/ sudo nano hello.service

The service definition must be on the /lib/systemd/system folder. Our service is going to be called "hello.service":

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[Unit] Description=Hello World After=multi-user.target   [Service] Type=simple ExecStart=/usr/bin/python /home/pi/hello_world.py Restart=on-abort   [Install] WantedBy=multi-user.target

Here we are creating a very simple service that runs our hello_world script and if by any means is aborted is going to be restarted automatically. You can check more on service's options in the next wiki: https://wiki.archlinux.org/index.php/systemd.

Now that we have our service we need to activate it:

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sudo chmod 644 /lib/systemd/system/hello.service chmod +x /home/pi/hello_world.py sudo systemctl daemon-reload sudo systemctl enable hello.service sudo systemctl start hello.service

For every change that we do on the /lib/systemd/system folder we need to execute a daemon-reload (third line of previous code). If we want to check the status of our service, you can execute:

1	sudo systemctl status hello.service

In general:

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# Check status sudo systemctl status hello.service   # Start service sudo systemctl start hello.service   # Stop service sudo systemctl stop hello.service   # Check service's log sudo journalctl -f -u hello.service

REFERENCES

1. https://wiki.archlinux.org/index.php/systemd
2. https://www.digitalocean.com/community/tutorials/understanding-systemd-units-and-unit-files
3. https://coreos.com/os/docs/latest/getting-started-with-systemd.html