Creating a service on Linux with systemd.

One might want to have its python script (or a program) to start automatically each time the system boots up. With systemd it is actually (relatively) easy ! Systemd is the service manager on the recent linux platforms. It enables us to create our own services.

Creating the service file

Create a file photonServerDeamon.service. In this file we want to write

[Unit]
Description=Service de démarage pour le serveur de comptage de photons
After=tlp-init.service

[Service]
Type=simple
ExecStart=/usr/bin/python3 "/home/someone/service/photonServerDeamon.py"
Restart=always
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=photonServerDeamon
User=root
Group=root

[Install]
WantedBy=multi-user.target

• Description is what it sounds like: it serves to describe your service
• ExecStart is the most important part : it specifies the command that must be executed to start the service; the path must be absolute
• Restart specifies if systemd should restart the service if it ends (eg: unforeseen crash)

Then move the file in the /etc/sytemd/system directory

sudo mv photonServerDeamon.service /etc/systemd/system/photonServerDeamon.service

And make sure that root can read, edit and execute this file

sudo chmod u+rwx /etc/systemd/system/photonServerDeamon.service

Enabling and starting the service

To enable the service use

sudo systemctl enable photonServerDeamon

The service will now be started during the next boot. It can also be started immediately with

sudo systemctl start photonServerDeamon

Debugging

If trouble arise use either

sudo systemctl status photonServerDeamon

to check the service status or

sudo journalctl -xe

to see went what went wrong.

Uninstalling

To disable a service just use

sudo systemctl disable photonServerDeamon

Note that the service file will not be deleted.