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From: perry@ccssrv.UUCP (Perry Hutchison)
Newsgroups: comp.unix.questions
Subject: Re: Password entry
Message-ID: <571@ccssrv.UUCP>
Date: 24 Aug 89 00:42:31 GMT
References: <10975@boulder.Colorado.EDU>
Reply-To: perry@ccssrv.UUCP (Perry Hutchison)
Distribution: usa
Organization: Control-C Software, Inc., Beaverton, OR
Lines: 15

In article <10975@boulder.Colorado.EDU> bobk@fred.colorado.edu (Bob Kinne)
writes:

>What is the purpose of the following /etc/passwd entry?
>
>::0:0:::	(null login, password, and shell)

On SunOS, an entry just like this except for a leading + means that login
should consult the YP (formerly "yellow pages", name changed due to
trademark issues) for additional valid logins.  This mechanism allows a
local Sun network to maintain one net-wide password file instead of having
to try to keep N separate files (one per system) up to date.

I suspect that the cited entry serves a similar purpose on your variety
of UN*X.