title: bash script to rename all files in a directory?
body: <p>i have bunch of files that needs to be renamed.</p>
  
  <pre><code>file1.txt needs to be renamed to file1_file1.txt
  file2.avi needs to be renamed to file2_file2.avi
  </code></pre>
  
  <p>as you can see i need the _ folowed by the original file name.</p>
  
  <p>there are lot of these files.</p>