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From: jhh@ihlpl.UUCP (Haller)
Newsgroups: net.unix-wizards,net.micro.att
Subject: Re: port not working!!
Message-ID: <688@ihlpl.UUCP>
Date: Thu, 13-Mar-86 10:23:17 EST
Article-I.D.: ihlpl.688
Posted: Thu Mar 13 10:23:17 1986
Date-Received: Fri, 14-Mar-86 07:02:19 EST
References: <125@ganehd.UUCP> <432@ethos.UUCP>
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Organization: AT&T Bell Laboratories
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Xref: watmath net.unix-wizards:17182 net.micro.att:987

I used to have problems with my 7300 port hanging on opens, when I discovered
a generic feature of setting CLOCAL.  I would open /dev/tty000 with
O_NDELAY, then set CLOCAL, and expect to be able to write immediately.
I discovered that CLOCAL has NO EFFECT during the ioctl.  Opening the
/dev/tty000 again, while the fd with CLOCAL set remains open, allows
writes to occur.  If you are trying to write before there is carrier
on the line, this may be the problem.

John Haller