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From: tim@ism780c.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: symbolic links are a botch
Message-ID: <6614@ism780c.UUCP>
Date: Tue, 16-Jun-87 17:11:36 EDT
Article-I.D.: ism780c.6614
Posted: Tue Jun 16 17:11:36 1987
Date-Received: Fri, 19-Jun-87 01:23:38 EDT
References: <7724@brl-adm.ARPA>
Reply-To: tim@ism780c.UUCP (Tim Smith)
Organization: Interactive Systems Corp., Santa Monica CA
Lines: 27

In article <7724@brl-adm.ARPA> rbj@icst-cmr.arpa (Root Boy Jim) writes:
< It would be like Version 6, right? I think `cd ..' didn't work at
< the `root' of a mounted file system.

Correct, it didn't.

On System V before release 3, and on TS 1.0 ( and, I suspect, on
all other AT&T Unix systems ), the kernel did not actually check
for "..".  Instead, it checked for inode == 2 and the second
character of the name being  "." and the file being a directory.

This allowed some interesting things:

	# umount /dev/dsk/usr.disk
	# mkdir /usr/a.dir
	# mount /dev/dsk/usr.disk /usr
	# cd /usr
	# ln .. a.dir

Now, if you do "cd .." from /usr, you end up in /, but if you
do "cd a.dir" ( which is a link to ".." ) from /usr, you end
up in the a.dir directory under /usr on the root file system.
-- 
Tim Smith			"Well if you want to say yes, say yes
{seismo,sdcrdcf}!ism780c!tim     And if you want to say no, say no
				'Cause there's a million ways to go
				 You know that there are"