Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!rutgers!rochester!pt.cs.cmu.edu!b.gp.cs.cmu.edu!Ralf.Brown@B.GP.CS.CMU.EDU
From: Ralf.Brown@B.GP.CS.CMU.EDU
Newsgroups: comp.sys.ibm.pc
Subject: Re: MS-DOS puzzle #1
Message-ID: <2451ddc4@ralf>
Date: 23 Apr 89 13:29:24 GMT
Sender: ralf@b.gp.cs.cmu.edu
Organization: Carnegie Mellon University School of Computer Science
Lines: 29

In article <2936@ihuxy.ATT.COM>, vg55611@ihuxy.ATT.COM (Gopal) writes:
}I don't think MS-DOS has stderr defined.  I think at one point, a very early
}point (DOS 1.00 ?), it didn't even have stdin and stdout defined, you only
}had keyboard / display services.  Later, stdin and stdout were defined, and
}the keyboard/display services were mapped to these.  At that time, they
}could have added stderr services, but they didn't.

There is indeed a stderr.  MSDOS opens five standard handles for a process:
      0 is stdin  (default CON)
      1 is stdout (default CON)
      2 is stderr (default CON)
      3 is stdaux (default AUX or COM1)
      4 is stdprn (default PRN or LPT1)

Whoever was responsible for COMMAND.COM simply decided not to implement
stderr, stdaux, or stdprn redirection.  stdaux is useless, though, since
it uses the unusable ROM BIOS serial port "services".

}If application programs and compilers seem to have stderr, I am quite sure
}that it is because they bypass DOS and use BIOS to write to the display
}directly.

No, they can use file handle 2, just like under Un*x.  I use stderr all the
time for error messages.
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