ledtest.c

简单程序

#include <stdio.h>

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