Set verbose mode on/off
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_VERBOSE, long onoff);
Set the onoff parameter to 1 to make the library display a lot of verbose information about its operations on this handle. Very useful for libcurl and/or protocol debugging and understanding. The verbose information will be sent to stderr, or the stream set with CURLOPT_STDERR(3).
You hardly ever want this set in production use, you will almost always want this when you debug/report problems.
To also get all the protocol data sent and received, consider using the CURLOPT_DEBUGFUNCTION(3).
0, meaning disabled.