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From: ekrell@hector..UUCP (Eduardo Krell)
Newsgroups: comp.unix.wizards
Subject: Re: Symbolic Links
Message-ID: <2864@ulysses.homer.nj.att.com>
Date: Tue, 25-Aug-87 20:34:30 EDT
Article-I.D.: ulysses.2864
Posted: Tue Aug 25 20:34:30 1987
Date-Received: Thu, 27-Aug-87 03:21:16 EDT
References: <8731@brl-adm.ARPA> <2789@ulysses.homer.nj.att.com>
Sender: daemon@ulysses.homer.nj.att.com
Reply-To: ekrell@ulysses (Eduardo Krell)
Organization: AT&T Bell Labs, Murray Hill
Lines: 46

In article <1362@bloom-beacon.MIT.EDU> tytso@thor.UUCP (Theodore Y. Ts'o) writes:

>Part of the Unix way is to be as flexible as possible.  I HOPE this is 
>optional (turned on with a system call, or some such), or are you,
>as a religious fanatic, going to force your way on everyone?

It could be made optional. I have no problems with that. It could be set up
on a per-user basis.

>The above paragraph assumes that someone at ATT is pushing this
>interpretation into SYS V.  (Why is it that mostly ATT posters think
>this is a good idea?)  If you're discribing a purely local hack, then
>I hope it stays that way.

I think symbolic links are very useful, but I believe the way they were
implemented in BSD is broken. I believe that if I do "cd /usr/include/sys"
and then "cd ..", I should end up in /usr/include (without the help of
a smart shell).
This is not a purely local hack. The behavior described above already exists
in ksh, which is quite popular. If symbolic links will be added to the
official System V, then I should think they should follow our proposal.

>Example: /mnt/paris is a link to /.
>When you boot up in single user mode, before any history is established,
>WHERE DOES .. POINT TO?  Since you don't think .. is a physical
>pointer, the answer '/' is going to require a lot of explaning.

Not so. when you "start up", you're in "/". When in "/", "cd .." will
keep you in "/". Now, if you do "cd /mnt/paris" and then "cd ..",
you'll end up in /mnt.
You can think of it as if there's an implicit "cd /" when the system boots.

> And
>if the kernal flips a coin, I'll let you explain to the user why he
>typed cd .. from / and ended up in /mnt.

there's no coin flipping. What you get when you type "cd .." is backing
up to the logical parent directory, the one you used to get to where you
are. In your example :

cd /          ; cd ..      => /
cd /mnt/paris ; cd ..      => /mnt
    
    Eduardo Krell                   AT&T Bell Laboratories, Murray Hill

    {ihnp4,seismo,ucbvax}!ulysses!ekrell