Path: utzoo!attcan!uunet!wugate!wuarchive!brutus.cs.uiuc.edu!tut.cis.ohio-state.edu!ucbvax!BRL.MIL!moss
From: moss@BRL.MIL ("Gary S. Moss", VLD/VMB)
Newsgroups: comp.sys.sgi
Subject: Re:  HELP: Low level terminal I/O
Message-ID: <8907281005.aa01485@VMB.BRL.MIL>
Date: 28 Jul 89 14:05:04 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 32

[Misha Pavel <mis@psych.Stanford.Edu> writes]
< Is there any way to look at the system buffer and or return
< from read() when no input was generated?

Probably the better way to go, rather than mucking around with the terminal
settings, is to use fcntl() as follows:

Where fd is a file descriptor returned from creat(), open(), dup(),
	fcntl(), or pipe().

#include <fcntl.h>

	(void) fcntl( fd, F_SETFL, O_NDELAY );

	/* to check the buffer... */
	if( read( fd, bufptr, bytes ) == 0 )
		; /* nothing to read */

To be portable to BSD systems, the following is more correct:

	got = read( fd, bufptr, bytes);

#ifdef BSD
	if( got == -1 && errno == EWOULDBLOCK )
		got = 0; /* act like System V */
#endif
	if( got == 0 )
		; /* nothing to read */

Do a 'man fcntl' for more info.
-moss