Adding Space between macOS Dock Icons

This macOS command line adds a small (about half icon wide) empty space to the macOS dock. The empty space can be positioned on the dock, via drag and drop, in the same way app icons can be moved.

defaults write persistent-apps -array-add '{"tile-type"="small-spacer-tile";}' && killall Dock

This is really useful to create app groups in the dock, divided by the empty space, to support clicking app icons.