Provided by: xhk_1.2-1_amd64
xhk - HalfKey Xorg Driver Utility
xhk [-m] [-d] [-h]
xHK is a half keyboard mirroring implementation to help one handed typist. Running xhk detaches the keyboard, and intercepts all input; processing it for space bar pushes as it goes. The space bar acts as a modifier if it is held at the same time as a standard letter. Modifying acts to mirror the input such that key presses are mirrored down the middle of the home row. Pressing space, and then releasing will still provide a single space character.
-d increase debug verbosity levels. -h display a friendly help message. -m mirror mode - All keys are changed to reversed keyboard layout. -t X11 related keycode test. -v show xHK version
Kieran Bingham. January 2019 XHK(1)