title: how to use sed to replace text in subfolders
body: <p>i use this code to replace some text in an HTML file:</p>
  
  <pre><code>sed -i 's/tttt/new-word/g' /home/zjm1126/*.html
  </code></pre>
  
  <p>This doesn't search for files in subfolders, though. How do I apply this command to subfolders?</p>