title: Pre-installed Maven on Mac OS X gives java.lang.ClassNotFoundException
body: <p>I tried to run pre-installed Maven with <code>mvn</code> command and get this error:</p>
  
  <p><code>Exception in thread "main" java.lang.NoClassDefFoundError: org/codehaus/plexus/classworlds/launcher/Launcher</code></p>
  
  <p>Running latest Mac OS X Mountain Lion and Java.</p>