Re: Explanation of Run-Levels?

["Alan Mead" <amead8695 home com>]

From: "Jon S. Jaques" <wayvirgo home com>
To: <redhat-list redhat com>
Sent: Wednesday, October 17, 2001 1:31 PM
Subject: RE: Explanation of Run-Levels?


> If I change from lv. 5 to 3, are all of the services associated with the
> higher levels nicely shutdown?

Try it and see.

> And I could maybe change to lvl. 2 (or 1 or 0?) to disconnect all users
and
> services so that I could run backups? Or maybe some other large task that
> can't be interrupted by connections, such as indexing large file systems
or
> something?

Switching to 0 shutsdown the machine IIRC.  Switching to 6 reboots it.
Don't know what runlevel 2 does but look in /etc/rc.d/rc2.d and see what's
in there.  The files are all symlinks to start up scripts in
/etc/rc.d/init.d .   Many sources cover this (more comprehensively than
you're likely to get on a list) in the section where they talk about system
initialization.

> Would switching from a high, "normal" level, such as 5 or 6, to the lowest
> level, and then back again be essentially the same as a reboot?

Switching to 6 would reboot the machine.  (IIRC).  Red Hat uses 5 is the GUI
mode ... don't know what happens when you switch to that, I guess it starts
those services.  But these numbers are nominal, not ordinal.  There is no
reason why reboot isn't 1 and single user mode 2, etc.  run level 3 isn't
more or less than 5 or 1.  Just different.

-Alan