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From: bammi@cwruecmp.UUCP (Jwahar R. Bammi)
Newsgroups: net.micro.atari16
Subject: Re: Redirection & chaining
Message-ID: <1653@cwruecmp.UUCP>
Date: Sat, 1-Nov-86 15:32:13 EST
Article-I.D.: cwruecmp.1653
Posted: Sat Nov  1 15:32:13 1986
Date-Received: Mon, 3-Nov-86 22:15:55 EST
References: <12250715809.8.G.BRI@DEEP-THOUGHT.MIT.EDU>
Reply-To: bammi@cwruecmp.UUCP (Jwahar R. Bammi)
Organization: CWRU Dept. of Computer Engineering, Cleveland OH
Lines: 44

In article <12250715809.8.G.BRI@DEEP-THOUGHT.MIT.EDU> G.BRI%DEEP-THOUGHT@EDDIE.MIT.EDU (Brian Totty) writes:
>
>	Could someone tell me if it is possible to redirect standard output
>	to a file, and then chain to a program with its output dumped to the
>	file.  What I want to do, is make a GEM shell for the Alcyon C compiler
>	along with build capabilities, to have a nice GEM c development
>	package.  I would like to have a way of grabbing any output from
>	the program to check for errors, etc.
>
>	Code samples to do the redirection would be great.  Is there any
>	way that this will work?  Do programs return error codes to the calling
>	program?  Thanks.
>
	The following code will redirect stdout to a file called 'foo'
		dup = Fdup(0);
		handle = Fopen("foo", 1); if handle < -5 ERROR;
		Fforce(0, handle);
		
	The following code executes another program and returns its exit
	status
		status = Pexec(0, "program.prg", tail, (char *)NULL);

	where :-
	program.prg : should be the complete pathname, including extention.
	tail :
		tail[0] = length of command tail;
		tail[1...len] = Command tail (args) '\0' terminated
	(char *)NULL for the environment means that the child process
		     inherits the environment of the parent. if you want
		     to pass an environment, it is of the form string of
		     strings, where each string if of the form "VAR=VALUE"

	The child process inherits all the open handles of the parent, so
	if you had redirected stdout in the parent, it will  be redirected
	in the child too.

	** BUG ALERT **
	Alcyon C (v4.14 and the earlier version) always returns success (0)
	status, even if there were compilation errors.
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