Explanation of chkconfig Levels

Question

What do the levels in chkconfig mean?

e.g.

chkconfig --levels 235 httpd on

Solution

This is what they mean:

0   Halt
1   Single-User mode
2   Multi-user mode console logins only (without networking)
3   Multi-User mode, console logins only
4   Not used/User-definable
5   Multi-User mode, with display manager as well as console logins (X11)
6   Reboot

So, when specifying a runlevel in chkconfig, you tell the service if it should be on or off in a certain runlevel.