title: keytool not working in Ubuntu: incorrect magic
body: <p>I am with Ubuntu 16.04 LTS. When I am in </p>
  
  <pre><code>$JAVA_HOME/jre/lib/security
  </code></pre>
  
  <p>and want to list the certificates in <code>cacerts</code>, with these commands:</p>
  
  <pre><code>keytool -list -keystore cacerts
  </code></pre>
  
  <p>it prompts me for password, so I enter the default password:</p>
  
  <pre><code>changeit
  </code></pre>
  
  <p>and an exception occurs:</p>
  
  <pre><code>keytool error: gnu.javax.crypto.keyring.MalformedKeyringException: incorrect magic
  </code></pre>
  
  <p>Why it this happenning?</p>