title: Replacing one column with a value from another in a tab-delimited file
body: <p>I have a tab-delimited .txt file that has the format of:</p>
  
  <pre><code>chrI    0   1   -4.231
  chrI    1   2   -3.257
  chrI    2   3   -2.653
  chrI    3   4   -2.102
  chrI    4   5   -1.685
  chrI    5   6   -1.331
  chrI    6   7   -1.036
  chrI    7   8   -0.728
  chrI    8   9   -0.527
  chrI    9   10  -0.401
  </code></pre>
  
  <p>Is there any chance I can get text wrangler to replace all of the entries in column 2 with the columnn 3 values such that column 3 is essentially duplicated? </p>
  
  <p>Such as this:</p>
  
  <pre><code>chrI    1   1   -4.231
  chrI    2   2   -3.257
  chrI    3   3   -2.653
  chrI    4   4   -2.102
  chrI    5   5   -1.685
  chrI    6   6   -1.331
  chrI    7   7   -1.036
  chrI    8   8   -0.728
  chrI    9   9   -0.527
  chrI    10  10  -0.401
  </code></pre>
  
  <p>Is there a way to do this in Perl?</p>