I'm getting this error when running my script:
`require': cannot load such file -- rdoc/usage (LoadError)
/Users/S/.rvm/rubies/ruby-2.2.2/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- rdoc/usage (LoadError)
from /Users/S/.rvm/rubies/ruby-2.2.2/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from pdf.rb:34:in `<main>'
gem 'rdoc', '~> 4.2.2'
Depending on your version of ruby, you may need to install ruby rdoc/ri data:
<= 1.8.6 : unsupported
= 1.8.7 : gem install rdoc-data; rdoc-data --install
= 1.9.1 : gem install rdoc-data; rdoc-data --install
>= 1.9.2 : nothing to do! Yay!
Successfully installed rdoc-4.2.2
rdoc/usage module was removed from rdoc quite some time ago, namely in Ruby 1.9.1 (when rdoc was still part of the Ruby core language). See https://bugs.ruby-lang.org/issues/2713 for a discussion or the SVN commit.
Thus, with recent Rubies, there is no way to use this module anymore. You should update your code to use alternatives to generate documentation.