Knock-based commands for your Linux laptop

Anonymous Reader writes “Using Linux and the HDAPS kernel drivers, you can access the embedded accelerometers on Lenovo ThinkPads, then process the accelerometer data to read specific sequences of “knocking” events — literally rapping on the laptop case with your knuckles — and run commands based on those knocks. Double tap to lock the screen, and knock in your secret code to unlock. You can also download and use article Perl scripts to customize your own knocking input environment.”