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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.unix
Subject: Re: Problem with patch and infinite directories
Message-ID: <2519@umcp-cs.UUCP>
Date: Wed, 16-Jan-85 12:35:37 EST
Article-I.D.: umcp-cs.2519
Posted: Wed Jan 16 12:35:37 1985
Date-Received: Fri, 18-Jan-85 03:31:45 EST
References: <792@enea.UUCP> <795@enea.UUCP> <4883@utzoo.UUCP> <1299@utah-gr.UUCP> <34@spar.UUCP>
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 22

(I've deleted net.sources.bugs; it doesn't seem appropraite anymore)

The super-user is allowed to create links to directories in most (probably
all) versions of Unix.  Until 4.2BSD, that was the ONLY way to make a new
directory: if you wanted to "mkdir foo", the procedure was

	mknod "foo" as a directory
	link "foo/." to "foo"
	link "foo/.." to the directory in which foo was being made

This can still be done in 4.2, to maintain (a semblance of) backward
compatibility.

In order to un-make a botched directory link, you have to use the unlink
system call.  Many systems now have a program (/etc/unlink) which just
"unlink"s its argument, to facilitate this.
-- 
(This line accidently left nonblank.)

In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@maryland