Find a string in a text file and add text at the beginning to that line in php
<p>I have a text file:</p>

<p>John customerA <br>
Michael customerB <br>
Joe CustomerA<br>
Jacky CustomerC<br></p>

<p>How to add 'active' string into the beginning of the text and only for 'customerA', so the output will be</p>

<p>active John customerA <br>
Michael customerB <br>
active Joe CustomerA <br>
Jacky CustomerC <br></p>

<p>Thanks</p>
