Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!pasteur!ucbvax!decwrl!hplabs!sdcrdcf!csun!csuna!abcscnge
From: abcscnge@csuna.UUCP (Scott "The Pseudo-Hacker" Neugroschl)
Newsgroups: comp.unix.xenix
Subject: Re: Unbufferred file I/O
Message-ID: <1220@csuna.UUCP>
Date: 20 May 88 03:58:41 GMT
References: <2961@crash.cts.com>
Reply-To: abcscnge@csuna.UUCP (Scott "The Pseudo Hacker" Neugroschl)
Organization: California State University, Northridge
Lines: 46

In article <2961@crash.cts.com> cline@pnet01.cts.com (Ben Humphreys) writes:

    [ stuff about how write is buffered, and wants to go unbuffered input ]

Use ioctl().  Set the terminal flags to:

#include <sys/types.h>
#include <sys/ioctl.h>
#include <termio.h>

	struct termio ttyold, ttynew;
		
	/* get the terminal params twice */
	if (ioctl(0,TCGETA,&ttyold) == -1 || ioctl(0,TCGETA,&ttynew) == -1)
	{
		perror("program");
		exit(-1);
	}

	/* set up for unbuffered I/O */
	ttynew.c_cc[VMIN] = 1;
	ttynew.c_cc[VTIME] = 0;
	ttynew.c_lflags &= ~ICANON;
	if (ioctl(0,TCSETAW,&ttynew) == -1)
	{
		perror("program");
		exit(-1);
	}

	/* Stuff to talk to other user here */


	/* clean up when done */
	ioctl(0,TCSETAW,&ttyold);
	exit(0);				/* done */


Note that you should catch SIGINT and probably SIGQUIT too, so that you 
can clean up gracefully before dropping dead.


-- 
Scott "The Pseudo-Hacker" Neugroschl
UUCP:  ...!ihnp4!csun!csuna!abcscnge
-- "They also surf who stand on waves"
-- Disclaimers?  We don't need no stinking disclaimers!!!