6. Systemd Goals

Lesson Content

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.

Exercise

View the unit statuses and start and stop a few services. What do you observe?

Quiz Question