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Run Level

Table of Contents

:Runlevels
Determine Current Runlevel

:Runlevels

The runlevels used by RHS 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)

Runlevel 0,6 is halt and reboot, 1 is maintenance mode.
Runlevel 2&3: getty on console, level 3 also getty on modem port.
Runlevels S and s are in fact the same. Internally they are aliases for the same runlevel.
Runlevels 7-9 are also valid, though not really documented and used.

A runlevel is a software configuration of the system which allows only a selected group of processes to exist. The processes spawned by init for each of these runlevels are defined in the /etc/inittab file. Init can be in one of eight runlevels: 0-6 and S or s.

The runlevel is changed by having a privileged user run init or telinit, which sends appropriate signals to init, telling it which runlevel to change to.

Runlevels 0, 1, and 6 are reserved. Runlevel 0 is used to halt the system, runlevel 6 is used to reboot the system, and runlevel 1 is used to get the system down into single user mode. Runlevel S is not really meant to be used directly, but more for the scripts that are executed when entering runlevel 1.