<?php
    $fh = fopen('db.txt','r');
    $file = fread($fh, filesize('db.txt'));
    $file = explode("\r\n", $file);
    fclose($fh);
    if( isset($_GET['linje']) ) {
        foreach( $file as $linjenr=>$linje ) {
            $linjenr++;
            if( $_GET['linje'] == $linjenr ) {
                $slett_linjenr = $linjenr-1;
                unset($file[$slett_linjenr]);
            }
        }
        $file = implode("\r\n", $file);
        $fh = fopen('db.txt','w');
        fwrite($fh, $file);
        fclose($fh);
        header("Location: flatfildatabase.php");
    }
    foreach( $file as $linjenr=>$linje ) {
        $linjenr++;
        echo $linjenr . ': ' . htmlentities($linje) . '<br />';
    }
?>
<form>
    <input type="text" name="linje" />
    <input type="submit" />
</form>