title: modify line in a .txt file in bash
body: <p>I have a .txt that contains lines and these in turn data separated by "," for example:</p>
  
  <pre><code>10,05,nov,2016,122,2,2,330,user
  </code></pre>
  
  <p>What I want is to be able to modify a parameter of an X line, which the search method is the first number, which is unique, is not repeated.
  For example find the number 10 (f1) and modify the row containing the 122 (f5).
  I've tried it with <code>sed</code> but I can't do it.
  I've commented that with <code>awk</code> I could, but I did'nt study that command.
  Some help??</p>