title: Installing RMagick Gem
body: <p>I just wanted to <code>gem install rmagick</code></p>
  
  <p>and got this:</p>
  
  <pre><code>Building native extensions.  This could take a while...
  ERROR:  Error installing rmagick:
      ERROR: Failed to build gem native extension.
  
  /usr/bin/ruby1.8 extconf.rb
  extconf.rb:1:in `require': no such file to load -- mkmf (LoadError)
      from extconf.rb:1
  </code></pre>
  
  <p>ImageMagick and libmagickwand-dev is already installed.</p>
  
  <p>Using Ubuntu Linux.</p>
  
  <p>Any help?</p>
  
  <p>Yours, Joern.</p>