Get the modification time of the remote resource
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FILETIME, long gettime);
Pass a long. If it is 1, libcurl will attempt to get the modification time of the remote document in this operation. This requires that the remote server sends the time or replies to a time querying command. The curl_easy_getinfo(3) function with the CURLINFO_FILETIME argument can be used after a transfer to extract the received time (if any).
HTTP, FTP, SFTP, FILE