Posted sometime before 2012

Systemd is a replacement for the traditional init scripts. This is the program that is launched when linux boots, and is the parent of all other processes.

Systemd using the Linux kernel feature control groups (or CGROUPS) to keep track of processes. This allows it to know when a program has stopped, and it can then be restarted. This is more robust then keeping and checking PID files or using daemon-start-stop. It is, however, not portable.

systemd Services

A systemd service is defined in a .service file. These files live in /usr/lib/systemd/system or /usr/lib/systemd/user.

Important properties for the .service files for us are in the [Service] section


and in the [Install] section it is often useful to define an alias

The name of the service is taken from the file name.

To start, stop and restart a service

# systemctl start my_prog.service
# systemctl stop my_prog.service
# systemctl restart my_prog.service

To get the status of a service

$ systemctl status my_prog.service
$ systemctl status annoy.service
   Loaded: loaded (/usr/lib/systemd/system/annoy.service; enabled)
   Active: active (running) since Mon 2013-10-21 13:50:02 WST; 48min ago
 Main PID: 19607 (python2)
   CGroup: /system.slice/annoy.service
           └─19607 python2 /home/lukec/test/pd/

Oct 21 13:50:02 bardeen systemd[1]: Starting annoy.service...
Oct 21 13:50:02 bardeen systemd[1]: Started annoy.service.

and to enable or disable a service from starting automatically at boot or being activated by systemd in other ways (such as DBus activation or socket activations

# systemctl enable my_prog.service
# ssytemctl disable my_prog.service

To take a look at the log file for a particular service do

journalctl -u example.service

Or if you are on a really old system

journalctl _SYSTEMD_UNIT=example.service