Linux Runlevel

In Linux, a "run level" refers to a specific state of the operating system in which a certain set of services and daemons are running. There are several predefined run levels, each with a specific purpose.

Linux Run Level (init 0)
ID	Name	Description
0	Off	Turns off the device.
1	Single-user mode	Mode for administrative tasks.
2	Multi-user mode	Does not configure network interfaces and does not export networks services.
3	Multi-user mode with networking	Starts the system normally.
4	Not used/user-definable	For special purposes.
5	Full mode	Same as runlevel 3+.
6	Reboot	Reboots the device.

Use the runlevel command /sbin/runlevel to find the current and previous runlevel of an operating system.