*BSD News Article 20636


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Newsgroups: comp.os.386bsd.bugs
Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!agate!howland.reston.ans.net!news.ans.net!cmcl2!prism.poly.edu!kapela
From: kapela@poly.edu (Theodore S. Kapela)
Subject: Re: bug with ufs file creation
Message-ID: <CD1Bux.JqL@poly.edu>
Organization: Polytechnic University, New York
References: <CCyLF6.n6@kithrup.com> <322@rook.ukc.ac.uk> <CCzu78.DJD@kithrup.com>
Date: Wed, 8 Sep 1993 12:25:45 GMT
Lines: 39

In article <CCzu78.DJD@kithrup.com> sef@kithrup.com (Sean Eric Fagan) writes:
>In article <322@rook.ukc.ac.uk> dac@ukc.ac.uk (David Clear) writes:
>>That's true BSD file creation semantics 
>
>"true BSD file creation semantics" are broken.  If I cannot do
>
>	chgrp bin foo
>
>without being in group bin, why is foo going to be in group bin depending
>on where I create it?

Remember where BSD came from:  RESEARCH

The intended "audience" (group of users) was a bunch of researchers openly
working together.  To facilitate this, if a group is working on a project, and
all of its files are under some heirarchy with a single root 
(Say, /usr/develop), then it is much more productive to have *all* files under
that heirarchy have the same group ownership, so all those working on that
project can readily have access (assuming the umask was set right, which it
normally was - the default would always be 022 or 002).  There was no need to
ask a specific user to explicitly change the ownerships (user/group) of a file
to allow others in his group to use it.

You can't count on all users working on a project to have the same primary
group (IE: group in /etc/passwd), especially since many users would move
between projects often, or would work on more than one project at once.

>At least the SGID bit is somewhat intuitive (since SGID means, inheiret
>the group id, for processes; it is just extended for directories and
>files, now).
Not exactly.  SGID and SUID bits on an executable mean to set the
EFFECTIVE Group ID or User ID.  There is a difference, though it is a subtle
one unless you write sofware that uses/needs to be aware of it.

-- 
Theodore S. Kapela				
Center for Applied Large-Scale Computing	
Polytechnic University
kapela@poly.edu