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From: katzung@laidbak.UUCP (Brian Katzung)
Newsgroups: comp.unix.wizards
Subject: Re: Separating input (tty) streams.
Message-ID: <1231@laidbak.UUCP>
Date: Fri, 6-Nov-87 19:10:15 EST
Article-I.D.: laidbak.1231
Posted: Fri Nov  6 19:10:15 1987
Date-Received: Wed, 11-Nov-87 01:51:17 EST
References: <15973@topaz.rutgers.edu> <1987Oct29.152901.2784@utfyzx.uucp> <1757@geac.UUCP>
Reply-To: katzung@laidbak.UUCP (Brian Katzung)
Organization: Lachman Associates, Inc, Naperville, IL
Lines: 20
Keywords: tty input streams sockets

The easiest way to do it is have /dev/ttyXX be the real tty, but don't
make it publicly writeable.  Require that stuff from other users (and
perhaps BSD biff type output?) go to a socket or FIFO managed by a
program.  In other words, modify write, talk, etc.  If you don't,
you have to modify things like init, so that it doesn't try to run
a getty on an unmonitored socket/FIFO, and ttyname(), so your processes
know what you're really using.

Using a control socket or FIFO, you would then send messages to this
monitor program telling it where to send stuff.  Under BSD, you could
even have it deliver stuff only when your shell has control of the
terminal (tty process group == shell process group).

The computer center at UC Berkeley had most of it's Televideo terminals
lobotomized because bored students would send commands to the status line
(of other people's terminals) and then send transmit-status-line-to-host.
It would have been much better to just make the terminals unwriteable and
modify write and talk.

-- Brian Katzung  ihnp4!laidbak!katzung