Path: utzoo!attcan!uunet!husc6!cmcl2!rutgers!mit-eddie!genrad!jpn
From: jpn@genrad.com (John P. Nelson)
Newsgroups: comp.unix.wizards
Subject: Re: none.
Message-ID: <13557@genrad.UUCP>
Date: 22 Nov 88 15:05:42 GMT
References: <9784@watdragon.waterloo.edu> <129@orac.UUCP> <4596@ptsfa.PacBell.COM>
Sender: news@genrad.UUCP
Reply-To: jpn@teddy.UUCP (John P. Nelson)
Organization: GenRad, Inc., Concord, Mass.
Lines: 24

>>Big mistake.  You've just probably destroyed all the user directories on
>>the machine, since ".*" matches "..", too.  Nice going.
>
>Maybe on some UNIX systems, but the man page for rm on System V states:
>
>	".... It is forbidden to remove the file .. merely to avoid
>	the antisocial consequences of inadvertently doing something like:
>
>		rm -r .*						"

This is true on Berkeley systems as well.  HOWEVER, it is easy to fool
rm, because the test only works when ".." is at the BEGINNING of the
filename.  I was quite surprised the first time I discovered this:  I
had written a "safe" rm which tucked files away in my "~/.backup" directory,
the idea was to clean out the ~/.backup directory when I logged out.

when I put the line "rm -rf ~/.backup/* ~/.backup/.*" into my .logout
file, I got a nasty surprise!  When I logged in again, my entire account
had been deleted!  ~/.backup/.* had expanded to ~/.backup/.., and rm
quite silently recursively removed my home directory!
     john nelson

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