Within Oracle Linux 7 introduction of systemd (systemd uses ‘targets’).The file /etc/inittab is no longer used to set the default run level. Editing /etc/inittab file with the same manner under Oracle Linux 5/6 will have no effect in Oracle Linux 7. Target units have a .target extension. Target units allow you to start a system with only the services that are required for a specific purpose.
To list the predefined systemd run level target units :
# find / -name "runlevel*.target" /usr/lib/systemd/system/runlevel4.target /usr/lib/systemd/system/runlevel5.target /usr/lib/systemd/system/runlevel6.target /usr/lib/systemd/system/runlevel1.target /usr/lib/systemd/system/runlevel2.target /usr/lib/systemd/system/runlevel3.target /usr/lib/systemd/system/runlevel0.target
Comparision of SysV Run Levels and Target Units
The table below shows the system-state targets which are equivalents of run-levels.
| Run Level | Target Units | Description |
|---|---|---|
| 0 | runlevel0.target, poweroff.target | Shut down and power off |
| 1 | runlevel1.target, rescue.target | Set up a rescue shell |
| 2,3,4 | runlevel[234].target, multi- user.target | Set up a nongraphical multi-user shell |
| 5 | runlevel5.target, graphical.target | Set up a graphical multi-user shell |
| 6 | runlevel6.target, reboot.target | Shut down and reboot the system |
To Check current default target
# systemctl get-default
The default target unit is represented by the /etc/systemd/system/default.target file. This file is a symbolic link to the default target unit file currently set.
# ls -l /etc/systemd/system/default.target lrwxrwxrwx. 1 root root 40 Oct 11 02:02 /etc/systemd/system/default.target -> /usr/lib/systemd/system/graphical.target
Use the runlevel command to view the SysV runlevel.
# runlevel N 5
Set a default target
To set a default target :
# systemctl set-default [new target]
for example :
# systemctl set-default multi-user.target rm '/etc/systemd/system/default.target' ln -s '/usr/lib/systemd/system/multi-user.target' '/etc/systemd/system/default.target'
Verify
Use the ls –l command to confirm that the default.target file is now a symbolic link to the multi-user.target file.
# ls -l /etc/systemd/system/default.target lrwxrwxrwx. 1 root root 41 Mar 24 01:53 /etc/systemd/system/default.target -> /usr/lib/systemd/system/multi-user.target
Set current target to default
When you set the default target unit, the current target remains unchanged until next reboot. To change the current target unit to default wihtout reboot use :
# systemctl default
or
# systemctl isolate default.target