Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!otter!jp
From: jp@otter.hpl.hp.com (Julian Perry)
Newsgroups: comp.sys.hp
Subject: Re: buggy hp9000/800 3.01 code?
Message-ID: <2980004@otter.hpl.hp.com>
Date: 1 Apr 89 08:10:04 GMT
References: <659@kcdev.UUCP>
Organization: Hewlett-Packard Laboratories, Bristol, UK.
Lines: 27

>The code we are using for raw input was extracted directly from Marc Roshkind's
>"Advanced UNIX Programming".  Specifically, pages 88-89.  He suggests
>termio.c_cc[VMIN] = 5 and termio.c_cc[VTIME] = 2.  I wasn't sure whether
>or not the bug was related to VMIN and VTIME or else ICANON.  I was
>finally able to get it to work by setting the VMIN value to 1 and the
>VTIME value to 0.

The following code fragment is the correct way to set the terminal modes to
read one character at a time (blocking for each one):

	ioctl(0,TCGETA,&modes);		/* Read the current settings */
	modes.c_lflag &= ~ICANON;	/* Off with line mode */
	modes.c_cc[VMIN] = 1;		/* Ask for 1 at a time */
	modes.c_cc[VTIME] = 0;		/* Ignore the timer */
	ioctl(0,TCSETAW,&modes);	/* Use the new settings */

I think that many implemetations of VMIN and VTIME are to ignore the timer
completely and effectively VMIN is always 1.  HP-UX used to be like this
a long time ago.  It's very MUX dependant.

Jules
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