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- In this video, we are going
to explore systemd targets.

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So what's a target?

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A target is a group of services.

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Some targets are isolatable.

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And that means that you
can use them as a state

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that your system should be started in.

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There's four of them,
emergency.target, and rescue.target,

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both of which are for troubleshooting,

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multi-user.target is a default state

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that a non graphical server will start in,

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and graphical.target is what you get

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if you start a fully
graphical environment.

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You can use systemctl
list-dependencies on a target to

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see the contents and
dependencies of a system target.

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And you can use systemctl,
get-default and set-default

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to find out which is your default.target,

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and to set your default.target.

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Let's go check this out.

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Okay, so I'm on my centos system and,

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well, I could use systemctl get-default,

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but honestly, if you see
a graphical user interface

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that shouldn't be necessary.

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You see the graphical user interface

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you are most likely in graphical.target.

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You wanna know what is going on.

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Well, systemctl list.dependencies
is going to help you,

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systemctl list.dependencies
without any argument

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is showing what you currently are in.

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So, we can see that I'm in default.target.

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In default.target. we have
all of these that are started.

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Now, default.target
includes multi-user.target.

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And in multi-user.target,

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we have all of this stuff
that has been started.

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And oh, we seem to have an
issue with kdump.service,

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nice way of telling us
that something is wrong.

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And next we can see that
the multi-user.target

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itself includes the
slice.target, the socket.target

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the sysinit.target,

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and so many more of these targets.

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So, these are the targets

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that are all in a state of isolatable.

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Now I want to show you

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systemctl list-units -t target,

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which is showing only units
that are of the type, target.

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Now, what do we see?

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We see, for instance

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bluetooth.target, now, bluetooth.target

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you can imagine these are all the services

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that are required to
initialize Bluetooth stack.

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But Bluetooth is not a state that

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you can boot your system into.

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So that is kind of confusing.

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Well, is it?

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Well, I don't think so,

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because really, in the
end, there are only four

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targets that you can put your system into.

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And these are emergency,
rescue, multi-user,

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graphical target.

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It's not much more difficult than that.

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And the other targets, are just groups.

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Groups that allow you to start one thing,

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and with this one thing,

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to initialize everything that is required,

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in this case for Bluetooth
support, for instance.