title: Add column to middle of tab-delimited file (sed/awk/whatever)
body: <p>I'm trying to add a column (with the content '0') to the middle of a pre-existing tab-delimited text file. I imagine <code>sed</code> or <code>awk</code> will do what I want. I've seen various solutions online that do approximately this but they're not explained simply enough for me to modify!</p>
  
  <p>I currently have this content:</p>
  
  <pre><code>Affx-11749850   1       555296  CC
  </code></pre>
  
  <p>I need this content</p>
  
  <pre><code>Affx-11749850   1   0   555296  CC
  </code></pre>
  
  <p>Using the command <code>awk '{$3=0}1'</code> filename messes up my formatting AND replaces column 3 with a 0, rather than adding a third column with a 0.</p>
  
  <p>Any help (with explanation!) so I can solve this problem, and future similar problems, much appreciated.</p>