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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.unix-wizards
Subject: Re: Disassocation from controlling tty
Message-ID: <615@umcp-cs.UUCP>
Date: Sat, 29-Mar-86 18:55:03 EST
Article-I.D.: umcp-cs.615
Posted: Sat Mar 29 18:55:03 1986
Date-Received: Sun, 30-Mar-86 10:51:28 EST
References: <515@ssc-bee.UUCP>
Reply-To: chris@maryland.UUCP (Chris Torek)
Distribution: net
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 25

In article <515@ssc-bee.UUCP> bossert@ssc-bee.UUCP writes:
>Where the desired goal is disassociation of a process from its
>controlling tty, what are the differences between

setpgrp() and ioctl(TIOCSPGRP)

>?  Which is preferable?  Why?

Neither.  Use

	if ((t = open("/dev/tty", 0)) >= 0) {
		(void) ioctl(t, TIOCNOTTY, 0);
		(void) close(t);
	}

I just checked the kernel code, and this changes u.u_procp->p_pgrp
too, so the setpgrp() call is unnecessary.

Note that if you execute this call without fork()ing, then wait
for some event, the shell will never regain control of the terminal
(if the process was started without `&').
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1415)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@mimsy.umd.edu