title: changing the output filenames in [split]
body: <p>I would like to split a huge text file into separate text files. I use:</p>
  
  <pre><code>split -l 1000 file.txt split_file
  </code></pre>
  
  <p>and I will get <code>split_fileaa</code>, <code>split_filebb</code>, etc.</p>
  
  <p>How can I change the extension to be </p>
  
  <p><code>split_file0.txt, split_file1.txt, etc</code>?</p>