Ubuntu – How to invoke the HUD

The HUD service is available as a service on DBus, so if you'd just like to poll it for information you can do that with a gdbus command, like this.

gdbus call --session --dest com.canonical.hud --object-path /com/canonical/hud --method com.canonical.hud.StartQuery "my query" 5

If you're trying to get Unity to show the HUD prompt you can do that with the XTest extension using xdotool like this:

xdotool key alt

If you're interested in playing with HUD it's probably best to use the hud-gtk tool which is in the indicator-appmenu-tools package.

The problem is your Desktop Environment i.e. Unity, is a plugin of the Window Manager Compiz. Similarly GNOME 3 is a plugin of Mutter.

So thing is that, the menus of your Window Manager are tightly coupled to the Dash of the Desktop Environment, which can be only done via a plugin.

If there were a Unity plugin for Mutter or Kwin or other Window managers, then they could be used too instead of Compiz