File system name space (was Re: Standards Update, IEEE 1003.4: Real-time Extensions)

[Arnold Robbins]

Submitted-by: arnold%audiofax.com at mathcs.emory.edu (Arnold Robbins)

(It's about time the subject line on this one got changed, don't you think?)
[Seems plausible to me.  -mod]

Anyway, since we're discussing what is and isn't in the POSIX name space,
I'd like to put in a plug for the /dev/fd directory.  Opening /dev/fd/7 is
equivalent to doing a dup(7); it is a generalization of the "treat '-' as
stdin" hack used by cat and awk (and others) and allows at least two shells
(ksh and rc [see your nearest V10 manual]) to do interesting things like set
up non-linear pipelines.  (At least I think rc does it.  I know ksh does.)

There's lot of existing practice on this one; it originated in V8, circa
1984 or earlier, and PD versions for various, more popular, Unix incarnations
have been around for some time as well.

(In fact, in V8 - V10, /dev/stdin, /dev/stdout, /dev/stderr, and /dev/tty are
links to /dev/fd/0, /dev/fd/1, /dev/fd/2, and /dev/fd/3, respectively.  The
last, in particular, is a nice generalization, and eliminates an ugly special
case in the kernel; init just does one more dup.)

It's going to be fun watching how /dev/fd will be presented as both for and
against the case for "fd-centric" Unix... :-)  Personally, I'm in the put-it-
in-the-filesystem camp.
-- 
Arnold Robbins				AudioFAX, Inc. | Laundry increases
2000 Powers Ferry Road, #200 / Marietta, GA. 30067     | exponentially in the
INTERNET: arnold at audiofax.com Phone:   +1 404 933 7612 | number of children.
UUCP:	  emory!audfax!arnold Fax-box: +1 404 618 4581 |   -- Miriam Robbins

Volume-Number: Volume 21, Number 209