Runlevels

How to set the startup runlevel

  1. Edit the file /etc/inittab
  2. In the file is a line like:

    id:3:initdefault:

    In this case the value 3 specifies the runlevel. Normally you will want this to be 3 to run in console mode or 5 to run an X session at startup. A value of 1 is single user mode and can be set when having problems with your system. Modify this value to the value you want.

Below is a list of runlevels and what they mean.

  • 0 - halt
  • 1 - Single user mode
  • 2 - Multiuser, without NFS (The same as 3, if you don't have networking)
  • 3 - Full multiuser mode
  • 4 - unused
  • 5 - X Session
  • 6 - Reboot

How to change runlevels while the system is running

A running system can be taken to single user mode by using the telinit command to request run level 1 as follows:

telinit 1

Any valid runlevel may be entered by typing this command followed by the desired runlevel value. Normally you will want to use 1, 3, or 5.