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From: grog@lemis.de (Greg Lehey)
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Subject: Re: FreeBSD 2.1 Help
To: tcg@ime.net
Date: Sun, 7 Jul 1996 18:22:10 +0200 (MET DST)
Cc: questions@FreeBSD.org (FreeBSD Questions)
In-Reply-To: <31DFE323.5F9@ime.net> from "Gary Chrysler" at Jul 7, 96 12:17:39 pm
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Gary Chrysler writes:
>
> (lots of good stuff omitted)
>
> Yea, I agree, Try several different tests.. :)
> Can't hurt.
>
> 99.999% of my experiance is Dos based. So I have no idea what
> -clocal does. You can bet I'm looking though.. :)

Sorry, I keep forgetting that I should explain these things.  To quote
the termios(4) man page,

     If CLOCAL is set, a connection does not depend on the state of the modem
     status lines.  If CLOCAL is clear, the modem status lines are monitored.

     Under normal circumstances, a call to the open() function waits for the
     modem connection to complete.  However, if the O_NONBLOCK flag is set or
     if CLOCAL has been set, the open() function returns immediately without
     waiting for the connection.

In stty, on is shown as clocal, and off is shown as -clocal.  The
modem control line to which it refers is DCD (Data Carrier Detect),
which only comes on when you have established a connection.  In the
olden days, before modems had autodial capability, this was
appropriate, but now it's a pain.

Greg