Detecting whether a session is locally or remotely logged in

Tony Langdon <[email protected]>
Newsgroups gmane.org.user-groups.mlug.main
Message-ID <[email protected]> 
Is there an easy way to determine if a shell session is local or remote to 
the system?  I need to determine this for certain applications 
(specifically, GPG key generation), and want to idiot proof my scripts.

Local can include in a local xterm as well as console.

Remote includes remote xterms and SSH sessions (mostly SSH).

Any thoughts?

FYI, the box is a fairly standard FC4 box.
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