Você encontrará a resposta na página de manual xdotool :
mousemove_relative [options] x y Move the mouse x,y pixels relative to the current position of the mouse cursor. --polar Use polar coordinates. This makes 'x' an angle (in degrees, 0-360, etc) and 'y' the distance. Rotation starts at 'up' (0 degrees) and rotates clockwise: 90 = right, 180 = down, 270 = left. --sync After sending the mouse move request, wait until the mouse is actually moved. If no movement is necessary, we will not wait. This is useful for scripts that depend on actions being completed before moving on. Note that we wait until the mouse moves at all, not necessarily that it actually reaches your intended destination. Some applications lock the mouse cursor to certain regions of the screen, so waiting for any movement is better in the general case than waiting for a specific target.
No seu caso, será:
xdotool mousemove_relative --sync 5 0