Re: Learning Debian - run level question?
On Fri, Nov 16, 2007 at 08:16:35AM -0600, Randy Patterson - [Tech] wrote:
> I've been using Debian/Linux for just less than year and have been
> irreversibly hooked. I've been studying up on the boot and initialization of
> the system and have a question about run levels. I know Debian defaults to
> using run level 2. There is a comment in /etc/inittab that states;
>
> # Runlevels 2-5 are multi-user.
>
> When i look at how a process has been started (just for example apache).
>
> debian:/home/me# sysv-rc-conf --list | grep apache
> apache2 0:off 1:off 2:on 3:on 4:on 5:on 6:off
>
> Sure enough, apache has been started on all run levels 2-5. So here's my
> question. On a default Debian system are all run levels 2-5 setup exactly the
> same making no difference to the run level you chose to run in?
Yes. Read debian policy (available as a package). Debian leave
run-level admin up to the administrator.
In case you're familiar with other unixes, another gotcha: Debian, like
other unixes, has what it calls single-user mode where only root can log
in. On other unixes, only the root filesystem is mounted (on some, only
in read-only mode). On debian, if you look at the scripts in
/etc/rcS.d followed by /etc/rc1.d, you'll see that single-user mode gets
you a fairly complete system with everything mounted, assuming that
there aren't boot problems to begin with. However, if there aren't boot
problems, why would you run single-user mode?
So if you ever want a real unix single-user mode, the only way to get
close in Debian is to use init=/bin/sh on the kernel command line so
that init doesn't run and inittab doesn't come into effect.
Doug.
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