To list the current run level
$ who -r
run-level 5 2008-07-22 21:35 last=5
To change the default Run level edit /etc/inittab
You can also switch to another run level number by issuing
$ init
For example,
$ init 3
Now the system switches from Run level 5 to Run level 3
To list the current run level
$ who -r
run-level 3 2008-07-22 22:35 last=5
In the above result notice the last part which states “last=5″. This indicates that the last run level was 5
When the system is running and if we want to apply patches or alter certain configurations, the above command comes in handy.
The other option to change the current level is
$ telinit <run level number>
