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.