Working with boot targets

We can work with boot targets using the systemctl command. We touched on systemctl earlier in this chapter. Let's use the Ubuntu distribution. We can check which target is currently the default and running in the shell in real time by doing the following:

philip@ubuntu:~$ systemctl get-default
graphical.target
philip@ubuntu:~$

From the preceding output, we can see that graphical.target is the default running target. Now, if we want to change between targets, we can use the systemctl command. Let's change to multi-user.target:

philip@ubuntu:~$ systemctl isolate multi-user.target

As soon as we press the Enter key, the system will ask us to authenticate:

We can also run systemctl to verify the status of multi-user.target:

We can return the system to the GUI environment by using the systemctl command:

Also, we can take a look at one of the targets to see its structure, using the systemctl command:

philip@ubuntu:~$ systemctl show network.target
 Id=network.target
 Names=network.target
 WantedBy=networking.service systemd-networkd.service NetworkManager.service
 Conflicts=shutdown.target
 Before=network-online.target rc-local.service
 After=NetworkManager.service network-pre.target systemd-networkd.service network
 Documentation=man:systemd.special(7) http://www.freedesktop.org/wiki/Software/sy
 Description=Network

 LoadState=loaded
 ActiveState=active
 SubState=active
 FragmentPath=/lib/systemd/system/network.target
 UnitFileState=static
 UnitFilePreset=enabled
 StateChangeTimestamp=Wed 2018-06-20 10:50:52 PDT
 StateChangeTimestampMonotonic=18205063
 InactiveExitTimestamp=Wed 2018-06-20 10:50:52 PDT
 InactiveExitTimestampMonotonic=18205063
 ActiveEnterTimestamp=Wed 2018-06-20 10:50:52 PDT
 ActiveEnterTimestampMonotonic=18205063
 ActiveExitTimestampMonotonic=0
 InactiveEnterTimestampMonotonic=0
 CanStart=no

From the preceding output, one of the key values is WantedBy. This tells us who relies on the network.target. We can see that NetworkManager.service relies on the network.target. There are also details regarding StateChangeTimestamp, Documentation, LoadState, and Description, to name a few.