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From: pitchers@prlhp1.prl.philips.co.uk (Steve Pitchers)
Newsgroups: comp.cog-eng,sci.math
Subject: Re: Formalizing location and distance in file retrieval systems
Summary: Unix filesystem is not a hierarchical tree.
Message-ID: <1129@prlhp1.prl.philips.co.uk>
Date: 8 Aug 90 09:54:14 GMT
References: <1801@nvuxr.UUCP>
Reply-To: pitchers@prlhp1.UUCP (Steve Pitchers)
Organization: Philips Research Laboratories, Redhill, UK
Lines: 22

Actually, the Unix filesystem is more than just a hierarchical tree.
Any file can be linked to any other, using either a hard link or a soft
link - see 'man ln'.

A file may belong to more than one directory, which would really cause 
havoc with the notion of 'distance'.  The 'distance' to a file
will vary depending on the route you take.

The super-user can even forge multiple hard links to directories -
completely breaking the illusion of a hierarchical tree.  The resulting 
potentional for confusion explians why this is restricted to being a
super-user privilege! 

On the positive side, the existence of alternative routes to files
can make it much easier to locate information than if a 'hierarchical
menu' approach has been used.  Taking the 'wrong path' can
still lead to the correct information, as alternative opinions on the
classification of the information can be catered for.


Steve   ---   pitchers@prl.philips.co.uk
   ~~~