#include <X11/extensions/XTest.h>
#include <X11/keysym.h>

int main(int argc, char **argv)
{
  Display* disp = XOpenDisplay( NULL );
  if( disp == NULL )
    return 1;
  XTestFakeKeyEvent( disp, XKeysymToKeycode( disp, XK_Num_Lock ), True, CurrentTime );
  XTestFakeKeyEvent( disp, XKeysymToKeycode( disp, XK_Num_Lock ), False, CurrentTime );
  XCloseDisplay( disp );
  return 0;
}