title: Add text to file at certain line in Linux
body: <p>I want to add a specific line, lets say <code>avatar</code> to the files that starts with <code>MakeFile</code> and <code>avatar</code> should be added to the 15th line in the file. </p>
  
  <p>This is how to add text to files:</p>
  
  <pre><code>echo 'avatar' &gt;&gt; MakeFile.websvc
  </code></pre>
  
  <p>and this is how to add text to files that starts with MakeFile I think:</p>
  
  <pre><code>echo 'avatar' &gt;&gt; *MakeFile.
  </code></pre>
  
  <p>But I can not manage to add this line to the 15th line of the file. </p>