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From: std-unix@ut-sally.UUCP (Guest Moderator, John B. Chambers)
Newsgroups: mod.std.unix
Subject: Re:  Case sensitive file names
Message-ID: <5913@ut-sally.UUCP>
Date: Sun, 5-Oct-86 18:25:25 EDT
Article-I.D.: ut-sally.5913
Posted: Sun Oct  5 18:25:25 1986
Date-Received: Mon, 6-Oct-86 05:41:41 EDT
Organization: IEEE 1003 Portable Operating System for Computer Environments Committee
Lines: 49
Approved: jbc@sally.utexas.edu

Date: Fri, 3 Oct 86 23:56:26 edt
From: mark@cbosgd.att.com (Mark Horton)
Subject: Re:  Case sensitive file names

>Finally, there are all those emulator writers.  They might find it easier;
>then again, they might not.  If I were going to do an emulator on top of
>MS-DOS, then (since I don't work for Microsoft) I would probably use the
>existing filesystem just as a base to build the POSIX filesystem, almost
>the way UNIX builds a named hierarchical filesystem space out of inodes.
>Going to case insensitivity wouldn't help me a bit, because of the other
>limitations Mark mentioned.  It might help Microsoft, because they could
>change the 8+3 convention at the same time.  But unless they were willing
>to do that, it wouldn't help them either.  VAX-VMS might be easier, but
>again there are other problems I would have to solve.  Case-insensitivity
>would help me some, but I'd still have a lot of work ahead of me.

I'm not concerned very much about the amount of work the emulator
writer has to do, but I am concerned about the quality of the
resulting emulation.  If I'm a user of an emulator which is written
on an otherwise-reasonable case insensitive filesystem (VMS comes
to mind) which emulates case sensitivity, then apparent POSIX filenames
will bear little resemblance to real native filenames.  Either there's
an external table somewhere not unlike the UNIX directory/inode # tables,
or else file names are somehow encoded into longer native filenames.
I'm living with the latter kind of system now (Sun's PC/NFS, which makes
UNIX filesystems look like DOS filesystems) and the contortions it has
to go through to fit ordinary UNIX file names into DOS filenames are
a serious inconvenience.  The former kind of system makes it impossible
to access native files from inside the POSIX environment, unless someone
is awfully clever.

On the other hand, if case insensitive is an option for the emulator,
then two possibilities occur: (1) the vendor of the native operating
system can otherwise upgrade their filesystem to allow a clean POSIX
implementation (maybe they will arrange that their native OS conforms
directly to POSIX; wouldn't you consider it strongly if the market
starts to demand POSIX compatibility?) and (2) True UNIX systems have
the option to evolve to case insensitive, should a study be done and
the world conclude that insensitive is better.

I agree that a study should be done; I have my own intuitive feelings
on the subject, and there is quite a collection of operating systems
out there that went to extra work to be case insensitive, they can't
all be wrong, can they?  But by all means, this would make a great
human factors study for somebody.

	Mark

Volume-Number: Volume 7, Number 18