lk/system/systemd/making-services.md

A service can consist of two files - the script to run (usually a shell script), and the .service file which describes when it runs.

The service file goes into the memorably-named directory /usr/lib/systemd/system/, where systemd will not notice your new service file. Try not to confuse this with /usr/share/systemd/ or /var/lib/systemd/, but do

To make a formal introduction between systemd and your service file, reload the daemon and check the list of units.

sudo systemctl daemon-reload
sudo systemctl list-units | grep ${service}

Once you enable the service, systemd makes a symbolic link from /usr/lib/systemd/system/ to /etc/systemd/system/.

Example - tracker.service

[Unit]
Description=Tracker

[Service]
Type=simple
ExecStart=/path/to/script

[Install]
WantedBy=multi-user.target

Types

• simple - the service runs forever. Other services do not stop it.
• oneshot - the service executes once, then stops.