I think 'base name' should be defined somehow (perhaps "see :ref:`os.basename`?)  And I agree that that second sentence should be made less ambiguous.  Perhaps "make the help messages use the same name that was used to invoke the program on the command line".  (Many people won't know that you can invoke the same script by more than one name on unix by using symlinks, which is what makes that statement read wrong in its current form.)