Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!ukma!tut.cis.ohio-state.edu!osu-cis!att!cbnewsh!mbb
From: mbb@cbnewsh.ATT.COM (martin.b.brilliant)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MS-DOS puzzle #1
Message-ID: <238@cbnewsh.ATT.COM>
Date: 22 Apr 89 12:38:49 GMT
References: <6893@bsu-cs.bsu.edu>
Organization: AT&T Bell Laboratories
Lines: 28

From article <6893@bsu-cs.bsu.edu>, by dhesi@bsu-cs.bsu.edu (Rahul Dhesi):
>      Question:  Why does COMMAND.COM allow redirection of standard
>      input and standard output, but not standard error?
> 
>      Answer:  MS-DOS, unlike UNIX, doesn't have a fork() system call;
>      therefore the MS-DOS command interpreter, unlike the
>      UNIX shell, can't redirect standard error.
> 
> THE PUZZLE.  Does the above make any sense?  If it does, why?  If it
> does not, what is the real answer to the question?

No, it does not make any sense.  In the first place, there is no such
thing as "UNIX".   UNIX(R) is a trademark of AT&T.  There are UNIX
systems.  MS-DOS is not a UNIX system and never was one.  If MS-DOS can
redirect standard input and standard output without fork(), it could
also redirect standard error if the designers of MS-DOS wanted it to.

The real answer to the question is that the designers of MS-DOS thought
it would be good to allow redirection of standard input and standard
output, but that error messages should always go to the screen.  So
they wrote MS-DOS to direct all error messages to the screen.

M. B. Brilliant					Marty
AT&T-BL HO 3D-520	(201) 949-1858
Holmdel, NJ 07733	att!cbnewsh!mbb or mbb@cbnewsh.ATT.COM

Disclaimer: Opinions stated herein are mine unless and until my employer
	    explicitly claims them; then I lose all rights to them.