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From: guy@sun.uucp (Guy Harris)
Newsgroups: net.unix,net.unix-wizards
Subject: Re: Gripes about /bin/sh AND /bin/csh
Message-ID: <4036@sun.uucp>
Date: Tue, 10-Jun-86 14:24:42 EDT
Article-I.D.: sun.4036
Posted: Tue Jun 10 14:24:42 1986
Date-Received: Thu, 12-Jun-86 00:34:04 EDT
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> ...if I hadn't been operating under the misguided assumption that operating
> systems don't support multiple incompable command languages...

You've obviously never used VMS, which supports DCL and the old RSX-11
MCR....

Operating systems like UNIX, which blessedly have command processors which
are ordinary user programs, and let a user specify what program is to be the
first program started for their login session, can support as many command
languages as you want.  ("csh" is a Berkeley addition, so you can argue
whether UNIX supports it as a standard command language or not.)

> Some of this information deserves to be more than just oral tradition; I'm
> not familiar enough with the USENIX community to know whether someone has
> compiled some of these idioms into a document.

Unfortunately, I doubt that anybody has.  The existence of Michael Baldwin's
trick of using null "exec" commands to open and close file descriptors
within the shell is implied by a comment buried in the manual - it says
under the "exec" command that "...if no other arguments are given, (it
causes) the shell input/output to be modified."  No Advanced Shell
Programming tutorial comes with the UNIX documentation, and that would be
the place to discuss redirection of other file descriptors, this trick,
etc..
-- 
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com (or guy@sun.arpa)