RunLevels in Linux

0 Halt the system.
1 Single-user mode
2 Local Multiuser with Networking but without network service
3 Full Multiuser with Networking
4 For Testing Purpose
5 Full Multiuser with Networking and X Windows
6 Reboot

How to Find Out Current Run Level Command

There are 7 run levels in linux as listed above, To check the current Run Level use the command:

# who -r
run-level 3  2015-01-03 08:10   


# cat /etc/inittab

How to Change Run Level Command

In order to change the run level in linux use init command:

# init 1