Systemd Goals

We won't get into the details of writing systemd unit files. We will however go over a brief overview of a unit file and how to manually control units.

Here is a basic service unit file: foobar.service

[Unit]
Description=My Foobar
Before=bar.target

[Service]
ExecStart=/usr/bin/foobar

[Install]
WantedBy=multi-user.target

This is a simple service target, at the beginning of the file we see a section for [Unit], this allows us to give our unit file a description as well as control the ordering of when to activate the unit. The next portion is the [Service] section, under here we can start, stop or reload a service. And the [Install] section is used for dependency. This is only the tip of the iceberg for writing systemd files, so I implore you to read up on the subject if you want to know more.

Now, let's get into some commands you can use with systemd units:

List units

$ systemctl list-units

View status of unit

$ systemctl status networking.service

Start a service

$ sudo systemctl start networking.service

Stop a service

$ sudo systemctl stop networking.service

Restart a service

$ sudo systemctl restart networking.service

Enable a unit

$ sudo systemctl enable networking.service

Disable a unit

$ sudo systemctl disable networking.service

Again, you have yet to see how much depth systemd gets into, so read up on it if you want to learn more.