Ubuntu Move window to next monitor keyboard shortcut

Run compiz configuration settings manager (ccsm). Go to Window Management > Put > Bindings > Put To Next Output. Click the Put To Next Output and set a keyboard shortcut.

$ ccsm

If using Ctrl + Alt + Up, you'll need to remove the current keyboard shortcut mapping which is under Desktop > Desktop Wall > Bindings > Move within wall > Move Up. Click the Move Up button and disable the key binding by unchecking the "Enabled" checkbox and clicking the OK button.