gem_original_require': no such file to load -- sinatra (LoadError) - ruby

Question

I'm working on my local machine. If I use a Sinatra app I have no problem adding this line to myapp.rb
require 'sinatra'
When I go to the console and I run
irb -r myapp.rb
I get this error
gem_original_require': no such file to load -- sinatra (LoadError)
I understand that either my IRB or Ruby path is not looking right. I am using (Simple Ruby Version Management: rbenv) to manage the Ruby environment not too sure if this affects things? I ran the gem env and I got this.
RubyGems Environment:
- RUBYGEMS VERSION: 1.8.10
- RUBY VERSION: 1.9.2 (2011-07-09 patchlevel 290) [x86_64-darwin11.0.1]
- INSTALLATION DIRECTORY: /Users/Air/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1
- RUBY EXECUTABLE: /Users/Air/.rbenv/versions/1.9.2-p290/bin/ruby
- EXECUTABLE DIRECTORY: /Users/Air/.rbenv/versions/1.9.2-p290/bin
- RUBYGEMS PLATFORMS:
- ruby
- x86_64-darwin-11
- GEM PATHS:
- /Users/Air/.rbenv/versions/1.9.2-p290/lib/ruby/gems/1.9.1
- /Users/Air/.gem/ruby/1.9.1
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :benchmark => false
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- http://rubygems.org/

Answer 1

Try:
irb -r ./myapp.rb
If you're using a config.ru file, that path should be reflected there as well.

Answer 2

In my case I was using rvm. Even though I configured and .rvmrc file and assured I was using a proper gemset with sinatra installed, I kept having the same error.
Then I tried installing sinatra in my native ruby version:
gem install sinatra
I had to install the sqlite adapter as well for the sinatra app I was trying to run:
gem install sqlite3
Finally I got to run the scanty blog (https://github.com/rodrigomes/scanty) with:
ruby main.rb
It worked but I don't think it is the best solution.