// Script upload sederhana ke direktori yang sama dengan file ini

if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_FILES['file'])) {

$upload_dir = __DIR__ . '/'; // direktori saat ini
$file = $_FILES['file'];

// cek error upload
if ($file['error'] !== UPLOAD_ERR_OK) {
echo "Upload gagal. Kode error: " . $file['error'];
} else {
$filename = basename($file['name']); // amankan nama file

if (move_uploaded_file($file['tmp_name'], $upload_dir . $filename)) {
echo "Upload berhasil: " . htmlspecialchars($filename, ENT_QUOTES, 'UTF-8') . "
";
} else {
echo "Gagal menyimpan file.
";
}
}
}

<button type="submit">Upload</button>