Managing systemd targets with systemctl

1 Environment #

This document applies to the following products and product versions:

SUSE Linux Enterprise Server 15 SP5, 15 SP4, 15 SP3, 15 SP2, 12 SP5
SUSE Linux Enterprise Server for SAP Applications 15 SP5, 15 SP4, 15 SP3, 15 SP2, 12 SP5
SUSE Linux Enterprise High Availability 15 SP5, 15 SP4, 15 SP3, 15 SP2, 12 SP5
SUSE Linux Enterprise High Performance Computing 15 SP5, 15 SP4, 15 SP3, 15 SP2
SUSE Linux Enterprise Desktop 15 SP5
SUSE Linux Enterprise Real Time 15 SP5

2 Managing systemd targets with systemctl #

systemctl is the systemd command for managing target units. systemd targets are different states that your system can boot into, comparable to System V runlevels. Unlike SysV runlevels, target units are named rather than numbered. For example, the graphical.target is comparable to SysV runlevel 5, multiuser with network and a graphical environment.

Complex targets, such as graphical.target, are meta targets made by combining a subset of other targets. You may create custom targets by combining existing targets, and modifying individual targets as needed.

There are over 80 targets listed in man 7 systemd.special. The next section (Section 3, “List of the most important targets”) lists the most important targets.

3 List of the most important targets #

default.target: The target that is booted by default. This is a symbolic link to another target, like graphical.target. This can be changed permanently via YaST (see xref linkend="sec-boot-runlevel-edit"). To change it for a session, rather than permanently, use the kernel parameter systemd.unit=TARGET-NAME.target at the boot prompt.
emergency.target: Starts an emergency shell on the console. Find it in your GRUB 2 menu, or enter it at the boot prompt as systemd.unit=emergency.target.
graphical.target: Starts a system with network, multiuser support, and a display manager.
halt.target: Shuts down the system.
multi-user.target: Starts a multiuser system with networking, and no graphical environment.
reboot.target: Reboots the system.
rescue.target: Starts a single-user system without networking.

To remain compatible with the System V init runlevel system, systemd provides special targets named runlevelX.target, mapped to the corresponding SysV runlevels numbered X.

To see the current target, use the command systemctl get-default.

Table 1: System V runlevels and systemd target units #

System V runlevel	`systemd` target	Purpose
0	`runlevel0.target`, `halt.target`, `poweroff.target`	System shutdown
1, S	`runlevel1.target`, `rescue.target`,	Single-user mode
2	`runlevel2.target`, `multi-user.target`,	Local multiuser without remote network
3	`runlevel3.target`, `multi-user.target`,	Full multiuser with network
4	`runlevel4.target`	Unused/User-defined
5	`runlevel5.target`, `graphical.target`,	Full multiuser with network and display manager
6	`runlevel6.target`, `reboot.target`,	System reboot

Important: systemd ignores /etc/inittab

The runlevels in a System V init system are configured in /etc/inittab. systemd does not use this configuration.

4 Commands to change targets #

Use the following commands to changegit target units:

Task	`systemd` Command	System V init Command
Change the current target/runlevel	`systemctl isolate` TARGET-NAME.target	`telinit` X
Change to the default target/runlevel	`systemctl default`	n/a
Get the current target/runlevel	`systemctl list-units --type=target` With `systemd` there is usually more than one active target. The command lists all currently active targets.	`who -r` or `runlevel`
persistently change the default runlevel	Use the Services Manager or run the following command: `ln -sf /usr/lib/systemd/system/` TARGET-NAME.target /etc/systemd/system/default.target	Use the Services Manager or change the line `id:` X:initdefault: in `/etc/inittab`
Change the default runlevel for the current boot process	Enter the following option at the boot prompt `systemd.unit=` TARGET-NAME.target	Enter the desired runlevel number at the boot prompt.
Show a target's/runlevel's dependencies	`systemctl show -p "Requires"` TARGET-NAME.target `systemctl show -p "Wants"` TARGET-NAME.target “Requires” lists the hard dependencies (the ones that must be resolved), whereas “Wants” lists the soft dependencies (the ones that get resolved if possible).	n/a