Re: es %dup

[Donn Cave <donn@u.washington.edu>]

>From es-owner@hawkwind.utcs.toronto.edu Fri Oct 16 12:08:58 1992
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To: Paul Haahr <haahr@mv.us.adobe.com>
Cc: es@hawkwind.utcs.toronto.edu
Subject: Re: es %dup 
In-Reply-To: Your message of "Fri, 16 Oct 92 14:28:36 EDT."
             <9210161828.AA25790@utopia.mv.us.adobe.com> 
Date: 	Fri, 16 Oct 1992 15:07:10 -0400
From: Scott Schwartz <schwartz@groucho.cs.psu.edu>
Message-Id: <92Oct16.150733edt.2613@groucho.cs.psu.edu>
Status: R
|   I also think
| that most shells are not very good at dealing with file descriptors.
| For instance, if you had a way to ask for an unused descriptor, you
| wouldn't have to worry about colliding with ones that are already in
| use.  In other words, if you are going to muck with descriptors,
| functionality like that of tcl or perl is prefereable to that of sh.
| Es could easily provide that functionality.  That would make it
| better than ksh for dealing with coroutines.

The case in question involves re-defining unit 0, which isn't something
for which you could substitute re-defining any arbitrary unused descriptor.
I start with unit 0 open on a streams pipe, and need to have the tty open
on 0 before executing interactive commands.

I have to admit I don't know how perl and tcl would deal with this issue,
so I'm unable to picture exactly what kind of functionality you mean.

	Donn Cave, University Computing Services, University of Washington
	donn@cac.washington.edu