<?php

    /* Recommend */
    //$file = __DIR__.'/keys.txt';

    $file = "D:\Farm\Keys.txt";

    $message = 'Success';
    $text = filter_input(INPUT_POST,'text');

    if (empty($text)) {
        $message = 'Errror, text required!';
    } else {
        file_put_contents($nameFile,$text+"\n",FILE_APPEND);
    }
?>
<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>Validation</title>
    </head>
    <body>
        Status: <?=$message;?>
    </body>
</html>