generally, typing the name of the program will run it (eg firefox for firefox, evolution for evolution etc).
EDIT: a quick browse of the gnome-osd README file gave me this:
- gnome-osd-client: a simple command-line client interface. See
gnome-osd-client(1) man page for more information.
So i'd try
for that one. for more options, you can try the double tab technique, whereby you type what you know of the command (in this case "gnome"), then hit tab twice, and it should show you a list of possible program names you can execute, which begin with "gnome".