how to use ruby debugger

gistfile2.txt

ruby-debug_for_shoes

# Using ruby-debug to debug shoes applications
require 'rubygems'
# This may be needed to get find the Readline shared object,
#   shoes must use a different path than ruby from command line
$: << '/usr/lib/ruby/1.8/i486-linux'
# Include like this, not just with require by itself
Shoes.setup do
  gem 'ruby-debug'
end
require 'ruby-debug'
# later in the code add the call to the debugger
# ...
debugger