File numlockbios.c of Package kbd.10239
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
int main() {
#define BIOS_DATA_AREA 0x400
#define BDA_KEYBOARD_STATUS_FLAGS_4 0x97
#define BDA_KSF4_NUMLOCK_MASK 0x02
int fdmem;
char c;
errno=0;
fdmem = open("/dev/mem", O_RDONLY);
if (fdmem < 0) {
fprintf(stderr, "Couldn't open /dev/mem; %s\n", strerror(errno));
goto finish;
}
if (lseek(fdmem, BIOS_DATA_AREA + BDA_KEYBOARD_STATUS_FLAGS_4, SEEK_SET) == (off_t) -1) {
fprintf(stderr, "Failed to seek /dev/mem: %s\n", strerror(errno));
goto finish;
}
if (read (fdmem, &c, sizeof(char)) == -1) {
fprintf(stderr, "Failed to read /dev/mem: %s\n", strerror(errno));
goto finish;
}
if (c & BDA_KSF4_NUMLOCK_MASK)
printf("on\n");
else
printf("off\n");
finish:
close(fdmem);
if (errno)
{
printf("unknown\n");
exit(EXIT_FAILURE);
}
return 0;
}