title: Modify column 2 only using awk and sed
body: <p>I have a list of 3 columns:</p>
  
  <pre><code>2547123456789,5391074043372870,639027123456789
  </code></pre>
  
  <p>I want to modify second column like this:</p>
  
  <pre><code>sed 's/\([0-9]\)\([0-9]\)/\2\1/g' so that it becomes:
  
  3519700434738207
  </code></pre>
  
  <p>My problem is how do I do  this in one line of awk/sed while leaving the other columns untouched so that my final file has:</p>
  
  <pre><code>2547123456789,3519700434738207,639027123456789
  </code></pre>
  
  <p>Thanks</p>