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From: batson@cg-atla.UUCP (Jay Batson X5927)
Newsgroups: comp.unix.questions
Subject: Re: \"+\" filename -> /bin/sh !
Message-ID: <968@cg-atla.UUCP>
Date: Wed, 21-Oct-87 11:30:37 EDT
Article-I.D.: cg-atla.968
Posted: Wed Oct 21 11:30:37 1987
Date-Received: Sat, 24-Oct-87 13:14:58 EDT
References: <3351@sol.ARPA> <18062@teknowledge-vaxc.ARPA>
Reply-To: batson@cg-atla.UUCP (Jay Batson X5927)
Organization: Compugraphic Corp. Wilmington, MA
Lines: 42

In article <18062@teknowledge-vaxc.ARPA> mkhaw@teknowledge-vaxc.ARPA (Mike Khaw) writes:
>in article <3351@sol.ARPA>, ken@cs.rochester.edu (Ken Yap) says:
>> 
>> Since + is a non-binary, you are effectively doing /bin/sh +.  Try
>> this:
>> 	/bin/sh +
>> and get an interactive sh. In fact any argument starting with +
>> will get you the same result.
>> 
>> My guess is that sh discards arguments starting with + so effectively
>> you are doing just /bin/sh. This is on SunOS 3.4.
>> 
>> 	Ken
>On Ultrix 1.2, from either /bin/csh or /bin/sh I get:
>	+: +: cannot open
>On Sun OS 3.4:
>	csh% /bin/sh +
>	+: Command not found
>	sh$ /bin/sh +
>	sh$
>On Sun OS 3.2, both csh and sh give you a /bin/sh subprocess.


Does the fact that things are working this way on the Sun and not on Ultrix
mean anything?  I haven't followed this discussion closely, but have
persons BESIDES Sun users found this to work?

The reason I ask is that Sun has provided us with "Yellow Pages" so
we can all login across networks and have one passwd file.  Note that
on clients, the last entry begins with a '+'.  The recommended rest-of-
entry leaves most fields blank.  Note that the passwd(5) indicates that
a blank "shell" field means /bin/sh by implication.

Now I haven't looked at src to see, but might /bin/sh be finding client
yellow pages passwd file entries and executing the shell?


(Yes, I know it's a stretch, but I haven't posted anything in a while,
and I wanted to "see my name in print").


Jay Batson