Re: CLOCAL, or catch-22

Article View: comp.bugs.sys5

Article #560

#560

From: sandy
Date: Fri, 07 Aug 1987 15:25

20 lines
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In article <325@nsta.UUCP> amos%nsta@nsc.com (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.

You can open the line with the O_NDELAY flag set meaning return without
waiting for carrier (for a communications line anyway) and then issue 
the ioctl to set CLOCAL.
sandy




-- 
sandy bryant
slb@virginia.edu
uunet!virginia!slb

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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!seismo!mimsy!umd5!virginia!boole!slb
From: slb@boole.acc.virginia.edu (sandy)
Newsgroups: comp.bugs.sys5
Subject: Re: CLOCAL, or catch-22
Message-ID: <225@boole.acc.virginia.edu>
Date: Fri, 7-Aug-87 11:25:26 EDT
Article-I.D.: boole.225
Posted: Fri Aug  7 11:25:26 1987
Date-Received: Sun, 9-Aug-87 08:39:44 EDT
References: <325@nsta.UUCP>
Reply-To: slb@boole.UUCP (PUT YOUR NAME HERE)
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Organization: University of Va., Charlottesville, VA
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