I know part of the function name, how I can search for it from the CLI

Hi All;

I know part of the function name "get_registration_auth" (this part of its name) while its name might be
"voipdb_get_registration_auth_gnugk",how can I search for the functions that its name contain "get_registration_auth"? 

Also if I donot know if "get_registration_auth" if a function or view or store procedure, but I am sure there is a
tableor function or view or store procedure which contain this name, so how can I find it? 

Actually this to be from the Linux CLI (I am using fedora) and not from the GUI.

- By the way: Does Postgresql has GUI? How to get it?

Regards
Bilal