How to bypass (pipe) curl_exec return value directly to a file?

Newbie question. I need to download a very large amount of xml data from a site using CURL. How to bypass (pipe) curl_exec return value directly to a file, without using memory allocation? set_time_limit(0); $ch = curl_init($siteURL); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); $mixed = curl_exec($ch); How to set/pipe $mixed as a (disk) file, so that data returned by curl_exec is directly saved to the disk-file, and not involving memory allocation? Thank you. -PHP 5 -Windows XP