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From: skumar@cbnewsh.ATT.COM (swaminathan.ravikumar)
Newsgroups: comp.unix.questions
Subject: setpgrp question
Keywords: setpgrp, unix system call
Message-ID: <6863@cbnewsh.ATT.COM>
Date: 22 Dec 89 15:05:16 GMT
Organization: AT&T Bell Laboratories
Lines: 27


If the following program is run you get the following error
message:

    "pg cannot reopen stdout"

By reading different sources I found out that a process can
break its control terminal by calling "setpgrp". I don't
understand this 100%. Why should the process lose the control
terminal? why do you need "setpgrp"?
I know that it is used to group processes to receive
signals. Does this mean that the processes in the group cannot
use stdin/stdout. I would like to hear from anybody who has used
this call in a real application to understand this better.

	#include <stdio.h>

	main()
	{
	    setpgrp();
	    system("pg /usr/tmp/junk");
	}

Thanks.

-- ravi
skumar@hocus.att.com