title: How to add duplicate word using regular expression?
body: <p>Instead of removing duplicate words using regular expression, how do I duplicate a word? My case: I have a list of emails that need to be turn to SQL queries.</p>
  
  <pre><code>buddy@gmail.com
  melinda@yahoo.co.uk
  terrence12@gmail.com
  </code></pre>
  
  <p>To:</p>
  
  <pre><code>mysql -e "select * from users where email='buddy@gmail.com" &gt; /tmp/buddy@gmail.com.xls
  mysql -e "select * from users where email='melinda@yahoo.co.uk" &gt; /tmp/melinda@yahoo.co.uk.xls
  mysql -e "select * from users where email='terrence12@gmail.com" &gt; /tmp/terrence12@gmail.com.xls
  </code></pre>
  
  <p>So how do I duplicate the email in every line?</p>
  
  <p>Note: Each of this query will return more than one row, that's why I'm doing each query individually. </p>