What is Run Level?
Linux has 7 different run levels; Each mode has it’s own list of settings for what services to start and what services to shutdown. Not only does this list contain what is supposed to be running, but also what order each service should be started in – a feature many Linux lovers like to point out that Windows lacks!!!!
* rc0.d – System Halted
* rc1.d – Single User Mode
* rc2.d – Single User Mode with Networking
* rc3.d – Multi-User Mode – boot up in text mode
* rc4.d – Not yet Defined
* rc5.d – Multi-User Mode – boot up in X Windows
* rc6.d – Shutdown & Reboot
Commands for each Run level are given as under;
# init 0 = Shutdown the system
# init 1 = Switch to single user
# init 2 = Switch to single user with networking
# init 3 = Switch to multi-user – boot in text mode
# init 4 = Not Defined Yet
# init 5 = Switch to multi-user – boot in X windows (Desktop)
# init 6 = Shutdown and reboot the system
How to Change the Run Level in LINUX/UNIX
Find inittab file in /etc directory and change the lines under given;
Replace 3 with your desired number i.e. 5
Please don’t use 0 or 6, your default run level otherwise you won’t be able to boot the system because it will restart the system or just shutdown the system without taking you to the shell.
Why you wanna change the Default Run Level?
Linux administrator mostly works at command line because its effective, efficient, fast and have lots of other good characteristics but when you actually install the system with default settings you just select the default installation settings and it always boot in X windows (means in run level 5), so you have to change the run level manually to save the precious system resources for other important tasks.