what does each runlevel number stand for

Question

Cause Ubuntu uses Upstart instead of init, there is some different from Red Hat.
But How can I get the list of each runlevel number standing for, such as init 0 means shutdown.
man init can't show the list. So which command or man page cant print the list.
Thx!

Answer 1

Try man telinit

However, the runlevels in Ubuntu are:

Code        Description
0           Halt
1           Single-user mode
2           Graphical multi-user with networking
3-5         Unused but configured the same as runlevel 2
6           Reboot

Answer 2

The correct runlevels on Ubuntu would be:

 Runlevel        Target Units                          Description
 ========================================================================================
     0           runlevel0.target, poweroff.target     Shut down and power off the system.
     1           runlevel1.target, rescue.target       Set up a rescue shell, single user mode.
     2           runlevel2.target, multi-user.target   Set up a non-graphical multi-user system -> - Network, - GUI.
     3           runlevel3.target, multi-user.target   Set up a non-graphical multi-user system -> + Network, - GUI.
     4           runlevel4.target, multi-user.target   Set up a non-graphical multi-user system -> special purposes.
     5           runlevel5.target, graphical.target    Set up a graphical multi-user system -> + Network, + GUI.
     6           runlevel6.target, reboot.target       Shut down and reboot the system.

Meaning:

-: Absent

+: Present

Answer 3

Run levels vary per distribution, but in general:

Runlevel 0: Power off, halted.
Runlevel 1: Single user mode.
Runlevel 6: Reboot.

Usually one of 3,4, or 5 stands for 'multi user', but there is much more variation in these.