Thread: Wont run in X, works fine in alt+F1 terminal

i have this code to determine which lights are on, on a keyboard.

but if i run it in x windows it doesn't work, i get the error

Code:

ioctl: Invalid Argument

but if i press ctrl+alt+f1 for example the code will work in one of these terminals fine.

is there a way to get it to work in x windows, or is ioctl limited to terminals ??

here is the code

Code:

#include <stdio.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <linux/kd.h>  /* Keyboard IOCTLs */
#include <sys/ioctl.h> /* ioctl()         */
#include <sys/types.h>
  
#define ERROR -1
 
void checkleds();
long int arg;
int main()
    {
       int fd;       /* Console fd (/dev/tty). Used as fd in ioctl() */
       //long int arg; /* Where the LED states will be put into.       */
 
          /* To use as the fd in ioctl(). */
          if ((fd = open("/dev/tty", O_NOCTTY)) == ERROR) {
             perror("open");
             exit(ERROR);
          }
          printf("first %d\n" , arg);
          /* Value stored in arg. */
          if (ioctl(fd, KDGETLED,&arg) == ERROR) {
             perror("ioctl");
             printf("%d\n", arg);
             close(fd);
             exit(ERROR);
          }
 
          /* Here we print out current LEDS. */
        checkleds();
    }
 
void checkleds()
    {
        /* LED_SCR = 0x1, LED_NUM = 0x2, LED_CAP = 0x4 */
 
        if (arg == LED_SCR) printf("Scroll Lock LED is on.\n");
        else if (arg == LED_NUM) printf("Numeric Lock LED is on.\n");
        else if (arg == LED_CAP) printf("Caps Lock LED is on.\n");
 
        else if (arg == LED_NUM + LED_CAP)
           printf("Numeric Lock and Caps Lock LEDs are on.\n");
 
        else if (arg == LED_NUM + LED_SCR)
           printf("Numeric Lock and Scroll Lock LEDs are on.\n");
 
        else if (arg == LED_CAP + LED_SCR)
           printf("Caps Lock and Scroll Lock LEDs are on.\n");
 
        else if (arg == LED_NUM + LED_SCR + LED_CAP)
           printf("Numeric Lock, Scroll Lock, and Caps Lock LEDs are on.\n");
 
        else if (arg == 0)
          printf("No LEDs are on. \n");
 
        }

thanks for any help in this matter

Did you try including <sys/kbio.h>, I think that is where KDGETLED is defined.

GETLED is defined in ioctl.h, i searched for kbio.h and it seems that it is used mainly for SPARC systems

oh okay, It should work in X unelss X is doing something to restrict it. ioctl's communicate directly to the kernel and then to the device, X must be restricting that ioctl, don't know why or how, I will try and do mroe research on this topic.

thanks a lot, this is really baffling me as well