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From: johnsson@decwrl.DEC.COM (Richard Johnsson)
Newsgroups: comp.unix.wizards
Subject: Re: wtmp problem
Message-ID: <9799@decwrl.DEC.COM>
Date: Sun, 10-May-87 19:30:16 EDT
Article-I.D.: decwrl.9799
Posted: Sun May 10 19:30:16 1987
Date-Received: Mon, 11-May-87 03:49:26 EDT
References: <7285@brl-adm.ARPA> <4593@columbia.UUCP> <361@vax1.ccs.cornell.edu> <480@uhccux.UUCP>
Reply-To: johnsson@decwrl.dec.com
Organization: Digital Equipment Corporation
Lines: 18

Several people suggesting that DECnet/Ultrix might be involved was enough of
a hint to get me interested. I happened to have the DECnet/Ultrix sources
lying around so I looked at dlogind.

The dlogind version of rmut (the procedure everyone uses to update utmp and
wtmp) opens wtmp for write, seeks to the end, and then writes, rather than
opening for write+append as other programs (like rlogind) do. If I
understand the comments (from Chris Torek?) about writes crossing blocks,
having the file open for append should fix this problem.

I have reported the problem to the DECnet/Ultrix people (by totally
unofficial means :-). I'm afraid you won't see the fix until sometime after
2.0 since that's already in the can.
-- 
	Richard Johnsson, DEC Western Software Lab, Palo Alto, CA
	UUCP:  {decvax,ucbvax}!decwrl!johnsson
        ARPA:  johnsson@decwrl.dec.com     DEC ENet: sonora::johnsson
	phone: +1 415 853 6676