What's the best way in terminal to move a file from deep in one directory to deep into another? E.g. /desktop/a/b/c/file.txt and I want to move the text file to /desktop/x/y/z/

Thanks for any help!
Have you looked at the mv command?

mv /desktop/a/b/c/file.txt /desktop/x/y/z/

will do what you want.

Read about mv by typing man mv from the command prompt in Terminal.app.