1 /*
2 用户层
3
4 ./a.out stat
5 */
6 #include <sys/stat.h>
7 #include <fcntl.h>
8 #include <stdio.h>
9 #include <stdlib.h>
10
11
12 int main(int argc, char const *argv[])
13 {
14 /* code */
15
16 if(argc != 3) {
17 printf("Usage: ./a.out file<device file> <led status>\n");
18 return -1;
19 }
20
21 int fd = open(argv[1], O_RDWR);
22 if(fd < 0 ) {
23 perror("open");
24 goto err_open;
25 }
26
27 unsigned char led_status = atoi(argv[2]);
28 write(fd, &led_status, 1);
29
30
31 close(fd);
32 return 0;
33
34 err_open:
35 return -1;
36 }
