use warnings;
use strict;
use X11::Protocol; 

my $x = X11::Protocol->new;
$x->event_handler ('queue');

$x->GrabKeyboard ($x->root, 0, 'Asynchronous', 'Asynchronous', 'CurrentTime');
my $count = 0;
while ($count++ < 30) {
    my %event = $x->next_event;
    my $name = $event{'name'};
    if ('KeyPress' eq $name) {
        ## process event
        print "key pressed!\n";
    }
}
$x->UngrabKeyboard ('CurrentTime');