https://wiki.ubuntuusers.de/Dienste/

Bei der Diagnose, welches Init-System aktuell zum Einsatz kommt, kann der Befehl:

   cat /proc/1/comm 

weiterhelfen. Die Antwort lautet entweder systemd oder init, wobei letzteres bei 
Ubuntu für die Kombination aus Upstart und SysVinit steht.

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How to set up a runlevel 3 in Debian 8?
https://unix.stackexchange.com/questions/210117/how-to-set-up-a-runlevel-3-in-debian-8

1) Systemd boots towards the target given by "default.target". This is typically a symbolic link to the actual target file.

2) Systemd keeps it's targets in /lib/systemd/system and /etc/systemd/system. A file in /etc/systemd/system takes precedence over those shipped with the OS in /lib/systemd/system -- the intent is that /etc/systemd is used by systems administrators and /lib/systemd is used by distributions.

Debian as-shipped boots towards the graphical target. You can see this yourself:

$ ls -l /etc/systemd/system/default.target
... No such file or directory
$ ls -l /lib/systemd/system/default.target
... /lib/systemd/system/default.target -> graphical.target
So to boot towards the multiuser target all you need do is to put in own target:

$ cd /etc/systemd/system/
$ sudo ln -s /lib/systemd/system/multi-user.target default.target

   oder

# systemctl set-default multi-user.target

   oder

root@kali:~# systemctl set-default runlevel3.target 
Created symlink /etc/systemd/system/default.target → /lib/systemd/system/multi-user.target.