runlevel: Check your current runlevel. Then change it

Written by Benjamin Cane on 2011-08-10

Today's commands are how you can check what runlevel your system is in and then change it.

Check the current runlevel:

[[email protected] tmp]# runlevel   
N 5

Change the current runlevel:

[[email protected] tmp]# init <new_level>

The run levels in Unix/Linux are used to define what state init (the parent of all processes) is in. Each distribution of Unix/Linux has different definitions of what run levels starts what processes.

Usually you can find the different definitions in /etc/inittab below is the one from a fedora box.

# Default runlevel. The runlevels used are:  
# 0 - halt (Do NOT set initdefault to this)  
# 1 - Single user mode  
# 2 - Multiuser, without NFS (The same as 3, if you do not have networking)  
# 3 - Full multiuser mode  
# 4 - unused  
# 5 - X11  
# 6 - reboot (Do NOT set initdefault to this)

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Benjamin's specialty is keeping the lights on for mission critical systems. He is currently building applications that enable high concurrency financial transactions.

Recently Benjamin published his first book; Red Hat Enterprise Linux Troubleshooting Guide. In addition to writing, he has several Open Source projects focused on making Ops easier. These projects include Automatron, a project enabling auto-healing infrastructure for the masses.


Publications

Identify, capture and resolve common issues faced by Red Hat Enterprise Linux administrators using best practices and advanced troubleshooting techniques

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