title: How to use "ln" create link for directories on linux?
body: <p>I tried linux command line "ln", seems it couldn't do this:</p>
  
  <pre><code>mkdir -p test1/test2/test3
  ln -s test4 test1 #I wish to create test4 as symbolic link to test1
  find test4
  </code></pre>
  
  <p>The result is weird:</p>
  
  <pre><code>$ls test1
  test2 test4
  </code></pre>
  
  <p>Well, test4 is a subdirectory of test1, not a link to test4.</p>
  
  <p>It didn't achieve what I expected. How should I achieve this?
  Thanks a lot.</p>