From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <7e4c861d0e6e737cdef79daa6ba6f4a2@collyer.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] dumb question
From: Geoff Collyer <geoff@collyer.net>
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Date: Fri,  5 Jul 2002 02:43:55 -0700
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> i have also damaged whole file trees by doing
> 'tar cf adir - | {cd /missspelled/dir; tar xf -}'

I did too, a long time ago, and the lesson I drew is: you shouldn't
use "cd directory; tar", you should write
	cd directory && tar
.  In shell scripts, the shell will generally exit if cd fails, but
obviously interactive shells don't.

On Plan 9 at least, you can avoid destroying the archive (at least by
confusing "c" and "x") by not using the "f" key letter and letting tar
read standard input and write standard output, thus:

	tar c >tarfile afile
	tar x <tarfile afile

(Performance is a little poorer than using the "f" key letter, but
correctness seems more important here.)  To destroy the archive, you
have to get "<" and ">" mixed up, which seems less likely.  If it's
that much of a problem, protect your archives ("chmod a-w tarfile").