title: replace column header for multiple tab delimited files
body: <p>I have more than 100 tab-delimited files with same column names. I would like to change one of the column names (column 2) from 'OLD' to 'NEW' in all the files in batch. Rest of the contents remains same in the files.<br>
  Can anyone help me how to do it with awk?</p>
  
  <p>eg. file.txt</p>
  
  <pre><code>INFO    OLD    CONF     DB     COSMIC
  NA      NA      9       .       53
  NA      NA      10      .       192
  NA      NA      8       .       41
  NA      NA      8       .       87
  NA      NA      8       .       94
  NA      NA      8       .       92
  NA      NA      10      .       192
  NA      NA      10      .       47
  NA      NA      10      .       87
  </code></pre>
  
  <p>I would like to change 'OLD' to 'NEW':</p>
  
  <pre><code>   INFO    NEW    CONF     DB      COSMIC
      NA      NA      9       .       53
      NA      NA      10      .       192
      NA      NA      8       .       41
      NA      NA      8       .       87
      NA      NA      8       .       94
      NA      NA      8       .       92
      NA      NA      10      .       192
      NA      NA      10      .       47
      NA      NA      10      .       87
  </code></pre>
  
  <p>I have tried the following script</p>
  
  <pre><code>#!/bin/bash
  for file in 'ls PATH';
  do
       awk 'NR==1 &amp;&amp; $2=="OLD"{$2=="NEW"}1' $file &gt; temp &amp;&amp; mv temp $file
  done
  </code></pre>