PHP download prompt script downloads to server as well - php

Question

I wrote a PHP script that creates a zipfile and prompts the browser for download. Not only does it download to the client, for some reason it also creates a duplicate zipfile in my server in the same directory as this script.
I only want this script to download to the client, and not a duplicate on my server.
$layoutName = $_POST['layoutName'];
$htmlContent = $_POST['htmlContent'];
$layoutDir = 'http://myapp.com/public/views/layouts/' . $layoutName;
$zipFileName = 'Myapp-' . $layoutName . '.zip';
$decompressedFolderName = 'Myapp-' . $layoutName;
$zip = new ZipArchive();
$zip->open($zipFileName, ZipArchive::CREATE);
if($zip)
{
// Add index.html
$zip->addFromString('index.html', $htmlContent);
// Add CSS Folder
$cssContent = file_get_contents($layoutDir . '/css/default.css', false);
$zip->addFromString('css/default.css', $cssContent);
} else {
echo 'Could not create zip';
}
$zip->close();
header('Content-Type: application/octet-type');
header('Content-Disposition: attachment; filename=Myapp-' . $layoutName . '.zip');
header('Content-Length: ' . filesize($zipFileName));
ob_clean();
flush();
echo file_get_contents($zipFileName);
exit;
UPDATE
PROBLEM SOLVED. This code now works!

Answer 1

That was my exact problem. I changed readfile() to file_get_contents(), and now it doesn't create the file on my server.