03day03misc_app

 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 }

 

转载于:https://www.cnblogs.com/baoshulin/p/6416199.html