title: Linux awk text file processing
body: <p>I have a file with a few thousand lines of data, each line is like: <code>a:b:c:d</code></p>
  
  <p>So for example: </p>
  
  <pre><code>0.0:2000.00:2000.04:2000.02
  </code></pre>
  
  <p>I want to get all a's in one file, b's in second file etc. How?</p>