title: Find and replace with sed in directory and sub directories
body: <p>I run this command to find and replace all occurrences of 'apple' with 'orange' in all files in root of my site:</p>
  
  <pre><code>find ./ -exec sed -i 's/apple/orange/g' {} \;
  </code></pre>
  
  <p>But it doesn't go through sub directories.</p>
  
  <p>What is wrong with this command?</p>
  
  <p>Here are some lines of output of <code>find ./</code>:</p>
  
  <pre><code>./index.php
  ./header.php
  ./fpd
  ./fpd/font
  ./fpd/font/desktop.ini
  ./fpd/font/courier.php
  ./fpd/font/symbol.php
  </code></pre>