Runlevels

Linux uses ‘runlevels’ to define the current capability of the system, for example, whether the system is running in single user, multi-user, text or graphical modes.

The default runlevel for when the system boots is defined in the file.

Edit this file and look for a line like this:

id:3:initdefault:

- the number specifies the default runlevel.

Valid runlevels are:

  • 0 - Halt the system
  • 1 - Single-user mode
  • 2 - Multi-user mode (without NFS)
  • 3 - Multi-user mode
  • 5 - Multi-user mode, graphical login
  • 6 - Reboot the system

The runlevel can be changed at run time using the init RUNLEVEL where RUNLEVEL is the runlevel you wnat to change to.