pipetest.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

extern int
main(int argc, char *argv[])
{
	ssize_t count;
	int flags;
	char buf;

	flags = fcntl(STDIN_FILENO, F_GETFL);
	if (flags == -1) {
		perror("fcntl(stdin, F_GETFL)");
		exit(EXIT_FAILURE);
	}

	flags = fcntl(STDIN_FILENO, F_SETFL, flags | O_NONBLOCK);
	if (flags == -1) {
		perror("fcntl(stdin, F_SETFL)");
		exit(EXIT_FAILURE);
	}

	count = read(STDIN_FILENO, &buf, 1);
	if (count == -1)
		perror("read");
	else
		printf("read: %zd bytes\n", count);
}