Date: Tue, 18 Jun 1996 15:56:34 -0400 (EDT) From: Brian Tao <taob@io.org> To: Troy Arie Cobb <troy@circle.net> Cc: freebsd-hackers@FreeBSD.org Subject: Re: odd results from w command Message-ID: <Pine.NEB.3.92.960618144827.26050E-100000@zap.io.org> In-Reply-To: <Pine.BSF.3.91.960616221230.1744B-100000@demeter.circle.net>
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On Sun, 16 Jun 1996, Troy Arie Cobb wrote:
> I had a user on the other day, let's call them
> foo. When I typed 'w', the results of the
> command went something like this:
> w: /dev//foo No such file or directory.
Your /var/run/utmp is corrupted. I had the exact same problem pop
up on a newly-installed 2.2-960501-SNAP system. I'd get something
like "w: /dev//ADD ROUTE: File exists" and some other garbage with the
'w' command. So far this has only happened with this one particular
server. None of our other 2.2-SNAP servers have experienced this yet.
I think I figured out how this happened on our server,
ns.ican.net. /var/run/utmp is cleared by /etc/rc on startup by
copying /dev/null over it. I wrote a Bourne script to automatically
update our secondary name servers from the data on ns.ican.net. That
script contained the line
rm -f boot2.tmp boot2.data 2>&1 /dev/null
Any *competent* /bin/sh programmer (i.e., not me ;-)) will notice
that /dev/null will be removed along with the boot2.* files. I forgot
about the extra '>' needed before /dev/null.
When the server is rebooted, error output of commands in various
startup files is sent to /dev/null. In our case, /dev/null was a
regular file. Then /etc/rc would 'cp /dev/null /var/run/utmp', and
that's how our utmp file was corrupted. Whew. :)
So if you still get the problem after a reboot, check your
/dev/null device. It may have accidentally been wiped out.
--
Brian Tao (BT300, taob@io.org, taob@ican.net)
Systems and Network Administrator, Internet Canada Corp.
"Though this be madness, yet there is method in't"
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