title: my bash may does recognize lowercase and uppercase are same
body: <pre class="lang-sh prettyprint-override"><code>mv readme.md README.md
  </code></pre>
  
  <p>then I getting message 
  <code>'readme.md' and 'README.md' are the same file</code></p>
  
  <p>why my ubuntu did not recognize lowercase and uppercase..?</p>
  
  <p><code>cd</code> it works well but, for example i wanna move src directory,</p>
  
  <pre class="lang-sh prettyprint-override"><code>CD src
  </code></pre>
  
  <p>then i getting message 
  <code>bash: CD: command not found</code></p>
  
  <p>without this kind of case, my bash works well..</p>
  
  <p>env ubuntu 18.04
  tell me about if get more my infomation to solve prob.</p>