Linux Runlevels

Runlevels define what tasks can be accomplished in the current state (or runlevel) of a Linux system. Every Linux system supports three basic runlevels, plus one or more runlevels for normal operation. The basic runlevels are shown in Table 1.

Table 1. Linux basic runlevels

Level	Purpose
0	Shut down (or halt) the system
1	Single-user mode; usually aliased as s or S
6	Reboot the system

Beyond the basics, runlevel usage differs among distributions. One common usage set is shown in Table 2.

Table 2. Other common Linux runlevels

Level	Purpose
2	Multiuser mode without networking
3	Multiuser mode with networking
5	Multiuser mode with networking and the X Window System