Ruby Debugger
While there are multiple ways to use Ruby debugger, for my first Ruby script (?) I found starting the script via rdbg to be the easiest.
Like rdbg myscript.rb
Debugger has all the basic command I have used elsewhere.
nfor nextppfor pretty printqfor quit
For subsequent times, using require 'debug' followed by binding.break may be better.
This README has all the details.