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From: bc@cyb-eng.UUCP (Bill Crews)
Newsgroups: net.micro.pc
Subject: Re: dos exec call (help)
Message-ID: <605@cyb-eng.UUCP>
Date: Sun, 28-Jul-85 20:00:55 EDT
Article-I.D.: cyb-eng.605
Posted: Sun Jul 28 20:00:55 1985
Date-Received: Thu, 1-Aug-85 07:11:20 EDT
References: <225@sdcarl.UUCP>
Organization: Cyb Systems, Austin, TX
Lines: 32

> I am considering the possibility of writing some subset of what looks like
> a unix "shell" (really just a history mechanism to cut down on repeated
> long command lines), since queries as to the existence of such a facility
> have been unsuccessfull. I have read the description of the dos EXEC call
> in the tech reference manual and in Norton's "programmers guide". I'm
> still a bit confused and remember some discussion about the subject a 
> while back. Could someone help me out with a more thourough description,
> and maybe an example of use? Are there tragic flaws to prevent such a
> scheme from working at all? I figure there must be stumbling blocks or
> someone would have succeeded at doing something like this already.

I don't have time to tell you *all* about it, but it does work, and a Unix-
like subshell is certainly do-able.  Just remember that the stack is totally
bombed upon return from the exec call!

> Another question:
> 	I am using the Mark Williams C compiler to port software written
> under Unix. They often read binary input from stdin. Such input is often
> cut off in the middle of a file (presumably because we run into a end of
> file character). Friends have run into this problem also. Is it really
> true that one cannot read binary input from stdin (a file), or is this
> a problem unique to the Mark Williams Compiler?

Use the ioctl call (int 21h, ah = 44h) to set the "binary" bit.  Remember
to set it back.
-- 

  /  \    Bill Crews
 ( bc )   Cyb Systems, Inc
  \__/    Austin, Texas

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