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From: phil@qfdts.OZ (Phil Chadwick)
Newsgroups: net.unix-wizards
Subject: Re:  Scanning stdin with no pause
Message-ID: <22@qfdts.OZ>
Date: Fri, 11-Jan-85 02:24:29 EST
Article-I.D.: qfdts.22
Posted: Fri Jan 11 02:24:29 1985
Date-Received: Wed, 16-Jan-85 04:38:05 EST
References: <6674@brl-tgr.ARPA> <6678@brl-tgr.ARPA>
Organization: Department of Forestry, Brisbane, Australia
Lines: 20


    >>     I am working with V7 UN*X.  I need a way to scan the standard input
    >> stream for a character, but not wait.
    >
    >This is not supported by 7th Edition UNIX.  You need to add something
    >to your kernel to do this directly; the Rand Corp. empty() call has
    >been distributed by USENIX a long time ago, and more recent approaches
    >include VTIME,VMIN in AT&T UNIX Systems III & V and select() in 4.2BSD.
 
VTIME and VMIN index the control character array in the termio structure
of USG systems.  They appear to be potentially very usefull, but I have
been unable to locate any printed documentation on how to manipulate
c_cc[VTIME] and c_cc[VMIN] to achieve a non-blocking read.  Can anyone
enlighten me please?
----
Phil Chadwick			Australia:	(07) 2296500
Department of Forestry		International:	+61 7 2296500
PO Box 5
Brisbane, Roma Street		SUN:	phil:qfdts		
AUSTRALIA	4001		UUCP:	{decvax,vax135}!mulga!phil:qfdts