Edit variable value in PHP file? - simple CMS

I’m trying to create a very simple way to update content on a website using a php script to edit the php pages themselves. All of the pages, index.php, about.php etc. only contain: a variable


which is the text of the page and an


call which loads the layout of the page.

I have this which can edit the full php page:

$mydir = ".";
$file = "index.php";

$writefile = $_REQUEST['writefile'];
$text = $_REQUEST['text'];
    $fd=fopen($mydir."/".$file, "w");
    fwrite($fd, stripslashes($text));
    echo "<font color=red><strong>File updated</strong></font>";
    echo "<meta http-equiv=\"Refresh\" content=\"3; URL=$PHP_SELF\">";
    $fp=fopen($mydir."/".$file, "r"); // $mydir$myfile
    while(!feof($fp)) {
        //$content .= fgets($body);
        $content .= fgets($fp, 4096);
    echo "<FORM ACTION='$PHP_SELF' METHOD='post'>";
    echo "<input type=hidden name=writefile value=true>";
    echo "<TITLE>Editor</TITLE>";
    echo "<TEXTAREA ROWS='20' COLS='80' NAME='text'>";
    echo "$content";
    echo "</TEXTAREA><BR>";
    echo "<input type='submit' value='Update'><br></form>";

It works great but how can i make it so it only loads the value of




instead of the whole php page? Since i’m only needing to edit the text, i only want to load that into the text form field. Thanks!