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From: nerd@percival.rain.com (Michael Galassi)
Newsgroups: comp.unix.sysv386
Subject: Re: TIOCNOTTY under SCO System V/386
Keywords: TIOCNOTTY
Message-ID: <1991Jun22.011114.14327@percy.rain.com>
Date: 22 Jun 91 01:11:14 GMT
References: <54@jeanluc.UUCP>
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Organization: Percy's UNIX, Portland, OR.
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stockett@jeanluc.UUCP (Jeffrey M. Stockett) writes:

>I'm trying to port over some code from a BSD machine to SCO System V/386,
>and I have run into a problem with the following lines:

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

Stab in the dark, looks like the debug code in rlogind.  If this is
the case, #undef DEBUG, the TIOCNOTTY is not a good thing to have
occur to the controlling terminal of an interactive session.

If I'm wrong, here is the code to replace the above fragment:

	(void) setpgrp();

This will dissociate you from the controlling terminal and will make
the next terminal you open the controlling terminal.  There are other
side effects to this call, read the man page and know how these may
affect you.

FYI, this is the relevant section from the BSD man page (tty(4)).

    A process can remove the association it has with its con-
    trolling terminal by opening the file /dev/tty and issuing
    an

         ioctl(f, TIOCNOTTY, 0);

And, here is the relevant section from the Xenix man page (setpgrp(S))

    There are many ramifications to be considered before
    invoking setpgrp. When a process is made a process group
    leader with setpgrp, the terminal that controlled the
    process that issued the setpgrp statement is lost as the
    controlling terminal for the new process group.  The new
    process group takes as its controlling terminal the next
    terminal it opens that is not already open.

I assume that the functionality of setpgrp is identical in sco xenix
and sco unix.

Cheers,
-m
-- 
Michael Galassi				| nerd@percival.rain.com
MS-DOS:  The ultimate PC virus.		| ...!tektronix!percy!nerd