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From: abs@nbc1.UUCP (Andrew Siegel)
Newsgroups: net.wanted.sources,net.unix-wizards
Subject: How do I arrange for I/O calls to tty's to timeout?
Message-ID: <117@nbc1.UUCP>
Date: Tue, 15-Oct-85 21:28:37 EDT
Article-I.D.: nbc1.117
Posted: Tue Oct 15 21:28:37 1985
Date-Received: Thu, 17-Oct-85 07:27:24 EDT
Distribution: net
Organization: NBC Computer Imaging, New York, NY
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I'm looking for an elegant way to achieve "timeout-able" data
reads from tty's (and sockets, if possible).  In other words,
to have a call like:

		c = getc_timed(stream,delay);

which would return some kind of recognizable code should the character
not be read from the specified stream within the specified delay.  (I'd
also like some kind of distinct returned value for EOF.)

I've done this in both System III and 4.2BSD (using two different methods,
both involving use of the SIGALRM signal), but I'd like to know if I'm
overlooking some more obvious facility in UNIX.  A transportable method
would be the best.

Can anyone point me in the right direction, or (even better) send me an
example of the method you use?

Thanks.

					Andy Siegel
					NBC Computer Imaging
					philabs!nbc1!abs