Programming Ruby Chapter #15

Discussion of Ruby command line arguments, environment variables, gems, and the Rake build tool.
Programming Ruby Chapter #17

Discussion of character encoding schemes (e.g. ASCII, UTF) and Ruby support.
Programming Ruby Chapter #20

Examples of Ruby integration with the world wide web.  The Rails framework is not utilized in these examples.
Programming Ruby Chapter #23

Discussion of the "duck typing" programming style.
Programming Ruby Chapter #26

Demonstration of safe levels, trusted objects, and tainted objects in Ruby.