title: Unix Shell Loop through files and replace texts
body: <p>I am fairly new to this stuff, and I need a shell file to loop through all ".xml" files in a folder, and do some text replacements.
  So far I have come up with this:</p>
  
  <pre><code>sed "s/old_text/new_text/g" testfile.xml -i
  </code></pre>
  
  <p>However, I want this to run on all xml files in the current folder, not just on "testfile.xml". Furthermore, how can I make a backup of the original file ?</p>
  
  <p>Any input is more than welcomed!
  Thankls a lot!</p>