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From: mcm@rti.UUCP (Mike Mitchell)
Newsgroups: comp.unix.wizards
Subject: Re: What kinds of things would you want in the GNU OS?
Message-ID: <3028@rti.UUCP>
Date: 9 Jun 89 15:37:24 GMT
References: <106326@sun.Eng.Sun.COM> <4315@ficc.uu.net> <338@arc.UUCP> <208@sopwith.UUCP> <2622@fenix.UUCP>
Reply-To: mcm@rti.UUCP (Mike Mitchell)
Organization: Research Triangle Institute, RTP, NC
Lines: 30

I have been reading the articles proposing different symantics for accessing
remote systems with some amusement.  Some say '//host', others '@/host' or
'/@host' or other varients.  All require some hackery to the name parsing
routines in the kernel (namei) so that it recognises some new syntax.  Why
not use the notation '/../system'?  There have been distributed systems using
this form since at least 1982.  An example of one is described in "The Newcastle
Connection - or UNIXes of the World Unite," Software - Practice and Experience,
vol. 12, December 1982.

Let me explain a bit about the '/../system' symantic.  The '/' is your normal
root, right?  What is the convention for directory entries '.' and '..' in V7,
System V, and BSD unix systems?  Isn't  '.' just a hard link to the current
directory?  Isn't '..' just a hard link to the parent of the current directory?
Now in the directory called '/', the entry '..' is a hard link to the current
directory also.  What happens if you unlink the '..' entry in the '/' directory
and mkdir a directory called '..'?  I'll tell you what happens.  You get a
directory called '..' accessible from '/'.  You can now chdir to '/..' and
get to a new directory.  Put anything you want in that directory.  Put
symbolic links pointing to NFS systems there.  Put mount points for NFS there.
Put the '/dev/net/systemname' character/block devices there.  It really doesn't
matter what you put there, because it is just another directory.  UNIX users
are used to '..' meaning go up a directory.  To go to another system, you should
go above the root on your own system, then down to another one ('/../system').
It all just makes sense.

Of course, if you want to extend a local group of systems into a larger
collection of systems, just add another '..' directory to the '/..' directory.
Then the hierarchy could be like '/../nearsystem', '/../../virgina/system',
'/../../oregon/system', '/../../../england/london/system', or any other kind
of subdivision.  The tree could just keep going up.