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Re: Where to view bootup info ? dmesg ??



On Wed, Dec 04, 2002 at 11:09:53PM +0100, Sebastiaan wrote:
> High,
> 
> On Wed, 4 Dec 2002, daves debian wrote:
> 
> > Can anyone tell me how to view the bootup screen, it goes by so fast ....
> >
> > I can use dmesg to view the kernel boot
> > I seem to have loads of error messages after the kernel boots
> > I have checked /var/log/... no go
> >
> > Somewhere about when fstab is mounted
> >
> > any ideas ?
> This should be in /var/log/syslog, /var/log/daemon.log, /var/log/kern.log.
> 

I'd just like to reiterate something said above.
The boot process can be devided into two sections, kernel boot and
service boot.  All the kernel messages from the kernel boot go into
/var/log/dmesg (written from the S55bootmisc.sh in rcS.d).  
The services start to boot when you see all the 
Starting sshd....				[ok]
lines go across the screen.  It's up to each service to log stuff if
they want to; there's no centralized logging service for those.  So, if
one of them is bugging out on you, it's hard to find it logged (unless
it's a nice and kind service).

This boundary is a little fuzzy when it comes to services that load
kernel modules, such as starting network services.  Part of that (the
part that has to do with the kernel) gets logged in /var/log/dmesg, but
there might be other parts that don't.  

One technique I have used to be able to read boot messages takes
advantage of the scrollback buffer in the console.  Boot to runlevel 3
(multiuser, no X) by editing /etc/inittab and changing 
>>> # The default runlevel.
>>> id:5:initdefault:
to
>>> # The default runlevel.
>>> id:3:initdefault:
When you are getting near the end of the boot process, hit <return> a
bunch of times.  When you get your console login prompt, it clears
whatever is currently on the screen, hitting <return> pushes stuff off
the screen so it won't be cleared.  (sorry, that's redhat, I think.  I
just checked and it seems the login prompt just comes at the end of the
boot sequence.  much nicer.  Yay Debian!)
You can then scroll back to see what went through the boot sequence (to
a point, I don't know what it is...) by holding down Shift and pressing
the PgUp key.  
Don't switch virtual consoles, or you will lose your scrollback buffer.

-ben

-- 
Ben Hartshorne     benAThartshorneDOTnet     http://ben.hartshorne.net
PGP keyserver:pgp.dtype.org          Please encrypt all communications

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