Do the download request without getting the body
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_NOBODY, long opt);
A long parameter set to 1 tells libcurl to not include the body-part in the output when doing what would otherwise be a download. For HTTP(S), this makes libcurl do a HEAD request. For most other protocols it means just not asking to transfer the body data.
Enabling this option means asking for a download but without a body.
0, the body is transferred