#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/ioctl.h>int main(int argc, char **argv){	int on;	int led_no;	int fd;	if (argc != 3 || sscanf(argv[1], "%d", &led_no) != 1 || sscanf(argv[2],"%d", &on) != 1 ||	    on < 0 || on > 1 || led_no < 0 || led_no > 3) {		fprintf(stderr, "Usage: leds led_no 0|1\n");		exit(1);	}	fd = open("/dev/leds", 0);	if (fd < 0) {		perror("open device leds");		exit(1);	}	ioctl(fd, on, led_no);	close(fd);	return 0;}