main.c

来自「嵌入式linux led 显示程序」· C语言 代码 · 共 30 行

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>

int main(int argc, char **argv)
{
	int on;
	int led_number;
	int fd;
	if (argc != 3 || sscanf(argv[1], "%d", &led_number) != 1 || sscanf(argv[2],"%d", &on) != 1 ||
	    on < 0 || on > 1 || led_number < 0 || led_number > 3) {
		fprintf(stderr, "Usage:\n");
		fprintf(stderr, "\t led led_number on|off\n");
		fprintf(stderr, "Options:\n");
		fprintf(stderr, "\t led_number from 0 to 3\n");
		fprintf(stderr, "\t on 1 	off 0\n");
		exit(1);
	}
	fd = open("/dev/led", 0);
	if (fd < 0) {
		perror("open device /dev/led");
		exit(1);
	}
	ioctl(fd, on, led_number);
	close(fd);
	return 0;
}