HELP: Low level terminal I/O

["Gary S. Moss", VLD/VMB]

[Misha Pavel <mis at 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