<?php
$file = 'file.csv';

if (file_exists($file)) {
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename('file.csv'));
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: ' . filesize('file.csv'));
ob_clean();
flush();
readfile($file);
exit;
}
?>