title: jstack - well-known file is not secure
body: <p>I am running tomcat 5.5 on x86_64 CentOS 5.7 using 32-bit Oracle Java 1.6.0.</p>
  
  <p>JVM process used by tomcat has 6421 pid. Tomcat is working fine.</p>
  
  <p>When run <code>jstack</code> it fails with:</p>
  
  <pre><code>[root@mybox ~]# jstack 6421
  6421: well-known file is not secure
  </code></pre>
  
  <p>To get any reasonable output, I need to use force option:</p>
  
  <pre><code>[root@mybox ~]# jstack -F 6421
  Attaching to process ID 6421, please wait...
  Debugger attached successfully.
  Server compiler detected.
  JVM version is 17.0-b16
  Deadlock Detection:
  
  No deadlocks found.
  (...)
  </code></pre>
  
  <p>The <strong>questions</strong> are:</p>
  
  <ol>
  <li>what does the error message <em>"well-known file is not secure"</em> mean?</li>
  <li>what is the "well-known" file?</li>
  <li>why/when does the <code>jstack</code> command not work without a force option?</li>
  </ol>
  
  <p>Thanks in advance.</p>