title: Replacing Filename characters with python
body: <p>I have some code which adds the word "_manual" onto the end of a load of filenames.. 
  I need to change the script so that it deletes the last two letters of the filename (ES) and then replaces it with _ES_Manual
  for example: AC-5400ES.txt --> AC-5400_ES_manual.txt</p>
  
  <p>How would i incorporate that function into this code?</p>
  
  <pre><code>folder = r"C:/Documents and Settings/DuffA/Bureaublad/test"
  import os # glob is unnecessary
  for root, dirs, filenames in os.walk(folder):
      for filename in filenames:
          fullpath = os.path.join(root, filename)
          filename_split = os.path.splitext(fullpath) # filename and extensionname (extension in [1])
          filename_zero, fileext = filename_split
          print fullpath, filename_zero + "_manual" + fileext
          os.rename(fullpath, filename_zero + "_manual" + fileext)
  </code></pre>