RHEL7: Boot systems into different targets manually

Note: This is an RHCSA 7 exam objective.

In the old days

Before Systemd, there were the following runlevels:

• 1, single: maintenance level,
• 2: level without network resources (NFS, etc),
• 3: multi-user level without graphical interface,
• 5: multi-user level with graphical interface.

Note: The default run level was set in the /etc/inittab file.

To get the current run level with the old way, type:

# runlevel

To change the current run level (where X is the run level), type:

# init X

Note: As seen before, levels 0 and 6 were respectively used for halting a system and for rebooting it.

Current State

With Systemd, new commands are available:

• systemctl rescue: to move to single user mode/maintenance level with mounted local file systems,
• systemctl emergency: to move to single user mode/maintenance with only /root mounted file system,
• **systemctl isolate**multi-user.target: to move to multi-user level without graphical interface (equivalent to previous run level 3),
• systemctl isolate graphical.target: to move to multi-user level with graphical interface (equivalent to previous run level 5),
• systemctl set-default graphical.target: to set the default run level to multi-user graphical mode,
• systemctl get-default: to get the default run level.

Additional Resources

Make sure you visit the Systemd page.

You can also watch Ralph Nyberg‘s video about Systemd targets (6min/2015).