dmesg bootup-info removed/overwritten by syslogd ?

Jez Hancock jez.hancock at
Sun Apr 4 22:05:56 PDT 2004

On Mon, Apr 05, 2004 at 01:15:29PM +0900, Rob wrote:
> I wanted to see my original bootup messages again. So I typed
> dmesg, but all I got were 'arplookup' lines.
> I'm puzzled, where the bootup messages have gone?

Overwritten by kernel debug messages.  There have been a number of
similar questions for a while, the gist is that when the dmesg buffer
gets filled up, it starts to overwrite itself.  This affects the
daily periodic output and makes it look munged.  I don't think any
solution has ever been offered up - I'd certainly be interested in it :P

> I have two files in /var/log: and dmesg.yesterday
> Both files are completely filled with this line:
>    arplookup failed: host is not on local network
> How can I see the original bootup messages from the kernel?

One way is to cat the output from bootup dmesg into a file at boot time
- in /etc/rc.local put this:

dmesg > /var/log/dmesg.boot

if you wanted to get fancy you could use the date(1) command to
timestamp the files ala:

dmesg > /var/log/dmesg.boot.`date "+%Y%m%d"`

> Do I have to reboot for that :( ?


Good luck.

Jez Hancock
 - System Administrator / PHP Developer  - Another FreeBSD Diary        - ipfw peruser traffic logging

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