- https://wiki.debian.org/systemd

- systemd (ab debian stretch)
https://wiki.ubuntuusers.de/systemd/systemctl/
   systemctl enable NAME_DER_UNIT_DATEI 
   systemctl disable NAME_DER_UNIT_DATEI 

/etc/systemd
/lib/systemd

https://wiki.ubuntuusers.de/systemd/Service_Units/
   systemctl is-enabled NAME_DER_UNIT_DATEI 
   systemctl edit SERVICEUNIT


- stefanux.de/wiki/doku.php/linux/runlevel

systemd

 Statt Runlevel wird bei systemd von „targets“ gesprochen.

Standard-target:

    anzeigen:      systemctl get-default

    ändern:        systemctl set-default multi-user.target


- Disable all display managers in (systemd based) ubuntu
https://unix.stackexchange.com/questions/526126/disable-all-display-managers-in-systemd-based-ubuntu

   Disable:

systemctl set-default multi-user;
reboot;

   Enable:

systemctl set-default graphical;
reboot;


- SysVinit, Upstart (debian stretch)
bridge between   sysvinit   and   systemd