The OS is abstracting away details about where the characters come from, which is a keyboard in this case. The characters could also come from other sources, su

The OS is abstracting away details about where the characters come from, which is a keyboard in this case. The characters could also come from other sources, such as a file, or a speech-to-text program getting input from a microphone. Key-up events make no sense for these sources. Essentially, the author wants to go down a layer of abstraction to use his keyboard not as a character input device but as a grid of buttons. By default, this will require special permissions on most linux distros (and rightly so, as it allows for keylogging), but this is a matter of changing one's udev configuration; root is not inherently required. In any case, the stated goal "to remotely navigate a robot over an SSH connection using the 'w', 'a', 's', 'd' keys" is misguided to begin with; what happens when your connection drops and the robot can't be stopped? Addendum: has the author thought about the case where the user is using a keyboard layout where the WASD keys are not together, or where the user is using a non-latin-alphabet keyboard? As someone who uses a dvorak-based layout, I am annoyed at how often developers screw the key/character distinction up and assume everyone uses qwerty.