Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!hao!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.questions
Subject: Re: What is the name of /dev/tty?
Message-ID: <9030@mimsy.UUCP>
Date: Sun, 18-Oct-87 12:05:25 EDT
Article-I.D.: mimsy.9030
Posted: Sun Oct 18 12:05:25 1987
Date-Received: Mon, 19-Oct-87 01:49:18 EDT
References: <1418@zyx.UUCP> <2903@aw.sei.cmu.edu>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 23

In article <2903@aw.sei.cmu.edu> pdb@sei.cmu.edu (Patrick Barron) writes:
>On 4BSD, you can find out the terminal connected to /dev/tty by digging
>it out of your process's u area.  If you don't have read access to /dev/kmem,
>your process can fork off a child temporarily, and use ptrace(2) to get at
>the info.

<valley guy accent on> Ewwww, gross! <valley guy accent off>

On 4BSD Vaxen, at least, the u. area is easily read with

	struct user *u = (struct user *)(0x80000000 - UPAGES*NBPG);

where UPAGES and NBPG can be obtained with

	#include <sys/param.h>

You can then read `u->u_ttyd' and other miscellany directly.
(And no, you cannot write over them.)

This, too, is ugly (but effective).
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris