Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!rutgers!sri-spam!ames!oliveb!sun!gorodish!guy
From: guy@gorodish.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: how do I make a process release its terminal?
Message-ID: <12572@sun.uucp>
Date: Mon, 2-Feb-87 14:58:54 EST
Article-I.D.: sun.12572
Posted: Mon Feb  2 14:58:54 1987
Date-Received: Tue, 3-Feb-87 22:14:04 EST
References: <118@lmi-angel.UUCP> <323@sol.warwick.ac.uk>
Sender: news@sun.uucp
Reply-To: guy@sun.UUCP (Guy Harris)
Distribution: world
Organization: Sun Microsystems, Mountain View
Lines: 23

>I would have thought the 'else perror(...);' was undesirable.  If you can't
>open /dev/tty it probably means you're already without a controlling terminal
>and the ioctl is simply unecessary.

True.  The standard idiom in all the daemons I've seen omits the
"perror".  You can, instead, check for errno == ENXIO, and only print
the error message if it's *not* ENXIO, since the "/dev/tty" driver
returns ENXIO if you don't have a controlling terminal.

> Don't you want a
>
>        setpgrp(getpid());
>
>after that, too, to fully dissociate it from the terminal (otherwise when you
>hit ^C, you'll still get the signal).

Nope.  First of all, "setpgrp" in 4BSD takes two arguments, so it
would be

	setpgrp(0, getpid());

and second, TIOCNOTTY *really* disassociates you from the terminal,
so it's not necessary.  TIOCNOTTY sets your process group ID to 0.