cool feature of dmesg.boot file

[Bartosz Giza]

Hi,

I have found quite interesting feature on one of router that lately i have 
taken to administer.
What i knew was that file /var/run/dmesg.boot holds data from kernel buffer 
that is taken right after file system(s) are mounted.
Lately i have found that one router writes to this file data from kernel 
buffer when system is going to reeboot. Below are few lines from this file.
What you can see are lines from kernel right before reeboot. I have never seen 
before such lines in this file. And this is quite interesting. Could anyone 
tell me how can i achieve such funcionality on other systems ? I have tried 
to find on google about this but i couldn't find anything similar to this.

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Waiting (max 60 seconds) for system process `vnlru' to stop...done
Waiting (max 60 seconds) for system process `bufdaemon' to stop...done
Waiting (max 60 seconds) for system process `syncer' to stop...
Syncing disks, vnodes remaining...2 2 2 0 0 done
All buffers synced.
GEOM_MIRROR: Device gm0: provider mirror/gm0 destroyed.
GEOM_MIRROR: Device gm0 destroyed.
Uptime: 71d13h58m11s
Copyright (c) 1992-2007 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 6.2-RELEASE #0: Sun Feb 18 20:05:19 CET 2007			
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Pozdrawiam
Bartosz Giza