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From: philip@axis.fr (Philip Peake)
Newsgroups: comp.bugs.sys5
Subject: Re: CLOCAL, or catch-22
Message-ID: <276@axis.fr>
Date: Mon, 10-Aug-87 06:08:13 EDT
Article-I.D.: axis.276
Posted: Mon Aug 10 06:08:13 1987
Date-Received: Wed, 12-Aug-87 04:45:06 EDT
References: <325@nsta.UUCP>
Organization: Axis Digital, Paris
Lines: 17
Summary: Try NODELAY

In article <325@nsta.UUCP>, amos@nsta.UUCP (Amos Shapir) writes:
| One of the optional flags of the c_cflag field of termio is CLOCAL. (see
| <termio.h>)  It is  supposed  to  cause the  tty  driver  to ignore  the
| 'carrier detect' bit  in the RS232 interface, and open  the line anyway.
| This is needed for  ports that do not have the DC  wired; trying to open
| such a port without setting the CLOCAL bit first, will cause the open to
| hang forever waiting for a carrier signal.
| 
| However, the  only way to set  this flag is  by a ioctl call;  the ioctl
| call needs  a file-descriptor  argument; a  file-descriptor can  only be
| obtained by a successfull open call...

Look at your manual, section 2, entry for 'open'.
There it tells you all about the flag O_NDELAY that you can
use when opening a device.

Philip