Understanding target dependencies
In this graphical.target file, the Requires=multi-user.target line means that multi-user.target has to be running before graphical.target can start. So, multi-user.target is a dependency for graphical.target. Now, let's peek into the multi-user.target file:
[Unit] Description=Multi-User System Documentation=man:systemd.special(7) Requires=basic.target Conflicts=rescue.service rescue.target After=basic.target rescue.service rescue.target AllowIsolate=yes
Here, we see that multi-user.target requires basic.target. So, let's look at the basic.target file to see what it requires:
[Unit] Description=Basic System Documentation=man:systemd.special(7) Requires=sysinit.target Wants=sockets.target timers.target paths.target slices.target After=sysinit.target sockets.target paths.target slices.target tmp.mount
Okay, basic.target requires sysinit.target. So, let's see what sysinit.target requires:
[Unit] Description=System Initialization...