title: Ubuntu 12.04 - RubyOnRails - gem install mysql2 seems to install but fails when i do: gem mysql2 - Unknown command mysql2
body: <p>I'm a Ror newbe and I'm attempting to create my first webapp with rails. 
  I'm encountering a problem when I installed gem mysql2:
  This is my actual configuration:</p>
  
  <p><strong>ruby -v: ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux]</strong></p>
  
  <p><strong>rails -v: Rails 3.2.3</strong></p>
  
  <p><strong>gem -v: 1.8.24</strong></p>
  
  <pre><code>michele@michele:~/rails/my_app$ gem install mysql2
  Building native extensions.  This could take a while...
  Successfully installed mysql2-0.3.11
  1 gem installed
  Installing ri documentation for mysql2-0.3.11...
  Installing RDoc documentation for mysql2-0.3.11...
  </code></pre>
  
  <p>After this I edited the database.yml and I run:</p>
  
  <p><strong>rake db:create</strong></p>
  
  <p>it returns: </p>
  
  <pre><code>rake aborted!
  Please install the mysql2 adapter: `gem install activerecord-mysql2-adapter` (mysql2 is not part of the bundle. Add it to Gemfile.)
  </code></pre>
  
  <p>So, when finally I try to install it I get the error:</p>
  
  <pre><code>michele@michele:~/rails/my_app$ gem install activerecord-mysql2-adapter
  ERROR:  Could not find a valid gem 'activerecord-mysql2-adapter' (&gt;= 0) in any repository
  ERROR:  Possible alternatives: activerecord-jdbch2-adapter, activerecord-jdbcmysql-adapter, activerecord-postgis-adapter, activerecord-jdbc-adapter, activerecord-odbc-adapter
  </code></pre>
  
  <p>Obviously I installed properly the others adapters but they don't fit with my needing of mysql2.</p>
  
  <p>Nothing else, I'm just stacked here. :)</p>