title: rails 3 generate controller not working
body: <p>i'm learning RoR, and I'm getting an error when generating a controller</p>
  
  <blockquote>
    <p><code>mitchell@ubuntu:~/Ruby/Website/blog$ rails generate controller posts</code></p>
  </blockquote>
  
  <pre><code>/home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/execjs-1.4.0/lib/execjs/runtimes.rb:51:in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/execjs-1.4.0/lib/execjs.rb:5:in `&lt;module:ExecJS&gt;'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/execjs-1.4.0/lib/execjs.rb:4:in `&lt;top (required)&gt;'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in `require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in `&lt;top (required)&gt;'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in `require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in `&lt;top (required)&gt;'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/coffee-rails-3.2.2/lib/coffee-rails.rb:1:in `require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/coffee-rails-3.2.2/lib/coffee-rails.rb:1:in `&lt;top (required)&gt;'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327@global/gems/bundler-1.2.1/lib/bundler/runtime.rb:68:in `require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327@global/gems/bundler-1.2.1/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327@global/gems/bundler-1.2.1/lib/bundler/runtime.rb:66:in `each'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327@global/gems/bundler-1.2.1/lib/bundler/runtime.rb:66:in `block in require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327@global/gems/bundler-1.2.1/lib/bundler/runtime.rb:55:in `each'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327@global/gems/bundler-1.2.1/lib/bundler/runtime.rb:55:in `require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327@global/gems/bundler-1.2.1/lib/bundler.rb:128:in `require'
  from /home/mitchell/Ruby/Website/blog/config/application.rb:7:in `&lt;top (required)&gt;'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/railties-3.2.9/lib/rails/commands.rb:24:in `require'
  from /home/mitchell/.rvm/gems/ruby-1.9.3-p327/gems/railties-3.2.9/lib/rails/commands.rb:24:in `&lt;top (required)&gt;'
  from script/rails:6:in `require'
  from script/rails:6:in `&lt;main&gt;'
  </code></pre>
  
  <p>I'm running Rails 3.2.9 and Ruby 1.9.3 on Ubuntu.</p>