mac empty spot in dock code example
Example: space in dock mac
defaults write com.apple.dock persistent-apps -array-add '{"tile-type"="spacer-tile";}'
#When the terminal prompt appears again type the following command
killall Dock
defaults write com.apple.dock persistent-apps -array-add '{"tile-type"="spacer-tile";}'
#When the terminal prompt appears again type the following command
killall Dock