I've looked through and experimented with predefined global constants,
but so far have not figured how to get the full path and name of the
Ruby interpreter and/or main script file from within a running program.
I want to distribute a program that can be installed in a folder chosen
by the user.  The program would save configuration information in the
same folder. In order to find the configuration file at runtime, I
thought I would query the full path of the Ruby interpreter or script
file.  In case it makes a difference, I'm using Windows.

Jamal