How can I get the keyboard state in Linux?

Question

I want to check if the user pressed down the Shift key when the program starts. (That means, press down the Shift key before the program is started) It\'s

Answer 1

AFAIK this cannot be done without Xlib (aka. X) with no root level permissions. Using XQueryKeymap() will do what you want. however you pointed out that X cannot be used. Regardless, opening display connection will also be required.

#include 
#include 
#include 
#include 

int main()
{
    Display* dpy = XOpenDisplay(NULL);
    char keys_return[32];
    XQueryKeymap( dpy, keys_return );
    KeyCode kc2 = XKeysymToKeycode( dpy, XK_Shift_L );
    bool bShiftPressed = !!( keys_return[ kc2>>3 ] & ( 1<<(kc2&7) ) );
    printf("Shift is %spressed\n", bShiftPressed ? "" : "not ");
    XCloseDisplay(dpy);
}