title: How could the UNIX sort command sort a very large file?
body: <p>The UNIX <code>sort</code> command can sort a very large file like this:</p>
  
  <pre><code>sort large_file
  </code></pre>
  
  <p>How is the sort algorithm implemented? </p>
  
  <p>How come it does not cause excessive consumption of memory?</p>