Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!tmsoft!mason
From: mason@tmsoft.UUCP
Newsgroups: comp.bugs.sys5
Subject: CLOCAL, or catch-22
Message-ID: <163@tmsoft.UUCP>
Date: Sat, 8-Aug-87 21:44:06 EDT
Article-I.D.: tmsoft.163
Posted: Sat Aug  8 21:44:06 1987
Date-Received: Sun, 9-Aug-87 12:45:30 EDT
References: <325@nsta.UUCP>
Reply-To: mason@tmsoft.UUCP (Dave Mason)
Followup-To: comp.bugs.sys5
Distribution: world
Organization: TM Software Associates, Toronto
Lines: 14

In sys5 if you open:
	x = open("/dev/ttyx",O_RDWR|O_NDELAY,0)
it will succeed even if there is no carrier on the line.  This is
documented in open(2).

CLOCAL doesn't seem to do much, except determine whether a subsequent open
without the O_NDELAY will wait for carrier or not.  So you do the open above,
diddle CLOCAL if you want & then you can do another open if you want to wait
for carrier.  CLOCAL probably also toggles DTR.  I gleaned this information
from the dialer (which I use all the time) posted by Gene Olson from
Quest Research last fall.

	../Dave Mason,	TM Software Associates	(Compilers & System Consulting)
	..!{utzoo seismo!mnetor utcsri utgpu lsuc}!tmsoft!mason