title: Ruby undefined local variable byebug
body: <p>I'm executing the file app.rb in my rails project and trying to step through it using the byebug gem, but I get an error saying 'byebug' is an undefined local variable.  I'm running the code using the command 'ruby app.rb'.  Is there a different way to step through a ruby file when executing it this way via the command line?</p>
  
  <pre><code>    $ bundle install
  Fetching gem metadata from https://rubygems.org/.....
  Resolving dependencies...
  Using byebug 6.0.2
  Installing pg 0.18.3
  Using bundler 1.6.2
  Your bundle is complete!
  Use `bundle show [gemname]` to see where a bundled gem is installed.
  $ ruby app.rb
  app.rb:17:in `block in &lt;main&gt;': undefined local variable or method `byebug' for main:Object (NameError)
      from app.rb:15:in `glob'
      from app.rb:15:in `&lt;main&gt;'
  </code></pre>