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From: hedrick@topaz.rutgers.edu (Charles Hedrick)
Newsgroups: comp.unix.wizards
Subject: Re: stupidity in directory management?
Message-ID: <13497@topaz.rutgers.edu>
Date: Fri, 24-Jul-87 00:28:00 EDT
Article-I.D.: topaz.13497
Posted: Fri Jul 24 00:28:00 1987
Date-Received: Sat, 25-Jul-87 11:38:02 EDT
References: <8414@brl-adm.ARPA> <1495@ihdev.ATT.COM>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 16

pdg@ihdev.uucp mentioned that he couldn't think of any use for
invisible files on TOPS-20.  Invisible files were added for the
archive system.  You want to keep information about the file in the
directory, so that you can do directories of all archived files, move
files back and forth between online and offline status etc.  On the
other hand, when you do "dir" you don't want to see all your
5-year-old junk.  So the compromise was that when you archive a file,
it stays in the directory, but is set to be invisible.  Unix also has
invisible files, which are used for similar reasons.  They are names
beginning with a dot.  On TOPS-20, invisibility is just a bit in the
fdb (inode), like deleted.  gtjfn (open) has an extra option to
control whether it is allowed to open invisible files.  The only use I
know of for invisible files outside the archive system is scaring
users.  If somebody leaves a job logged in in a public room, people
sometimes set all their files invisible.  (At less friendly
installations, people are known to delete them.)