title: double for loop with bash programming
body: <p>I'd like to do something like this with bash programming </p>
  
  <pre><code>for file_x in file1, file2, file3, etc...  
    for file_y in file1, file2, file3, etc...  
      if file_y != file_x
        do something 
  </code></pre>
  
  <p>any tips how to go about it? </p>