<?php
//editServer.php
$serverName = $_POST['serverName'] //assuming you have an html form previous

$filename = 'config.txt';  //the name of your file
$string = "servername \"" . $serverName . "\"" ;

$fp = fopen($filename, 'w');
fwrite($fp, $string);
fclose($fp);
?>



/*************
//Previous html form

<form action="editServer.php" method="POST">
<input type="text" name="serverName" />
<input type="submit" value="Edit" />
</form>



*************/