title: How does '..' works in directory address?
body: <p>I interpret <code>..</code> as previous directory so I expect <code>/</code> == <code>/home/..</code>. I tried:</p>
  
  <ol>
  <li><code>ls -a /</code></li>
  <li><code>ls -a /home/..</code></li>
  </ol>
  
  <p>and was expecting same result. But the result was different a little.</p>
  
  <p>What am I doing wrong?</p>
  
  <p><img src="https://i.stack.imgur.com/2svtd.png" alt="result image"></p>
  
  <p>The result of <code>ls -a /home/..</code>:</p>
  
  <blockquote>
    <ul>
    <li>.</li>
    <li>..</li>
    <li>.DS_Store</li>
    <li>.DocumentRevisions-V100</li>
    <li>.OSInstallerMessages</li>
    <li>.Spotlight-V100</li>
    <li>.TempReceipt.bom</li>
    <li>.TemporaryItems</li>
    <li>.file</li>
    <li>.fseventsd</li>
    <li>.installer-compatibility</li>
    <li>.vol</li>
    <li>Applications</li>
    <li>Library</li>
    <li>System</li>
    <li>Users</li>
    <li>Volumes</li>
    <li>cores</li>
    <li>home</li>
    <li>mnt</li>
    <li>opt</li>
    <li>private</li>
    <li>usr</li>
    </ul>
  </blockquote>
  
  <p>The result of <code>ls -a /</code>:</p>
  
  <blockquote>
    <ul>
    <li>.</li>
    <li>..</li>
    <li>.file</li>
    <li>.fseventsd</li>
    <li>.DS_Store</li>
    <li>.Volumeicon.icns</li>
    <li>.vol</li>
    <li>Applications</li>
    <li>Volumes</li>
    <li>etc</li>
    <li>sbin</li>
    <li>Library</li>
    <li>bin</li>
    <li>home</li>
    <li>tmp</li>
    <li>System</li>
    <li>cores</li>
    <li>opt</li>
    <li>usr</li>
    <li>Users</li>
    <li>dev</li>
    <li>private</li>
    <li>var</li>
    </ul>
  </blockquote>