In a graphical environment, this starts up a pretty nice graphical tool, although you might get a warning message:
Gtk-Message: 17:51:14.716: Failed to load module "canberra-gtk-module"
Correcting this error message is as simple as installing the correct modules:
sudo apt install libcanberra-gtk-module libcanberra-gtk3-module
After doing this, starting observer should result in the familiar
:ok and a graphical
application for looking at the running system.