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From: msb@sq.UUCP
Newsgroups: comp.cog-eng,comp.unix.xenix,comp.unix.wizards
Subject: Re: Request for human interface design anecdotes (and a cure?)
Message-ID: <1987Nov27.011955.10801@sq.uucp>
Date: Fri, 27-Nov-87 01:19:55 EST
Article-I.D.: sq.1987Nov27.011955.10801
Posted: Fri Nov 27 01:19:55 1987
Date-Received: Sun, 29-Nov-87 14:37:51 EST
References: <3103@psuvax1.psu.edu> <1987Nov21.014754.19660@sq.uucp> <392@xyzzy.UUCP>
Reply-To: msb@sq.UUCP (Mark Brader)
Organization: SoftQuad Inc., Toronto
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Having had my knowledge of UNIX* insulted in public, I feel obliged to
reply in public.  This is positively my last posting on the topic.
[And if you see it twice, it's not MY fault, I canceled the first one.]

> >In short, the proper UNIX flavored method for protecting important files
> >from "rm" is to turn off the write permission bit.

> I'm sorry if that's what you want, because that's not what your system
> is going to do.

And then he quotes the V7 manual at me, and explains why permissions work
as they do.  Well, he should have read one more paragraph:

#   If the a file has no write permission and the standard input is a
#   terminal, its permissions are printed and a line is read from the
#   standard input.  If that line begins with `y' the file is deleted,
#   otherwise the file remains...

This is precisely the kind of interactive prompting that one school of
"rm is too powerful" users like.  But you only get it when you want it.
Sure, write protecting the file doesn't affect what rm has *permission*
to do ... it affects what it *will* do.

As I said in my original posting, I do consider it a misfeature that
if stdin is NOT a terminal then rm proceeds regardless of the file's
permissions.  I think the -f flag should be required in that mode also.
(I also think that having said that should have been sufficient
prevention from having UNIX basics explained to me on the net.)

While I'm posting, I'll add the bit I left out the first time.  I have
made it a habit *not* to hit Return instantly upon typing a line that
has both "rm" and "*" in it.  I pause and reread it.  It's an easy habit
to establish, and it's all the protection I think I need against "rm * .o".

Mark Brader		"Male got pregnant -- on the first try."
utzoo!sq!msb			Newsweek article on high-tech conception
msb@sq.com			November 30, 1987

*"UNIX is a trademark of Bell Laboratories" is a religious incantation.