Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!pasteur!ucbvax!tut.cis.ohio-state.edu!osu-cis!att!cbnewsc!tjr
From: tjr@cbnewsc.ATT.COM (thomas.j.roberts)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MS-DOS puzzle #1
Message-ID: <552@cbnewsc.ATT.COM>
Date: 24 Apr 89 15:45:19 GMT
References: <238@cbnewsh.ATT.COM>
Organization: AT&T Bell Laboratories
Lines: 26

From article <238@cbnewsh.ATT.COM>, by mbb@cbnewsh.ATT.COM (martin.b.brilliant):
> 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 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.

It's even worse than that (!) - you CAN redirect file-descriptor 2 in
a program that then EXECs another program. Unfortunately, some programs
put error messages onto file-descriptor 2, and some put them directly
onto the screen. The "designers" (:-^) of MS-DOS decided NOT to standardize
how error messages are presented.

	[IMHO that was a very arrogant attitude on their part, and is merely 
	 one instance of why MS-DOS is so difficult to do serious applications
	 in (e.g. look at the TSR mess)].

Tom Roberts
att!ihnet!tjr