Unknown option: "-3" Unix manual page for CURLOPT_DEFAULT_PROTOCOL. (host=minya system=Darwin)
CURLOPT_DEFAULT_PROTOCOL(3)curl_easy_setopt optionsCURLOPT_DEFAULT_PROTOCOL(3)

NAME
       CURLOPT_DEFAULT_PROTOCOL  - default protocol to use if the URL is miss-
       ing a scheme name

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DEFAULT_PROTOCOL,  char
       *protocol);

DESCRIPTION
       This  option  tells  libcurl  to  use  protocol if the URL is missing a
       scheme name.

       Use one of these protocol (scheme) names:

       dict, file, ftp, ftps, gopher, http, https, imap, imaps,  ldap,  ldaps,
       pop3, pop3s, rtsp, scp, sftp, smb, smbs, smtp, smtps, telnet, tftp

       An  unknown or unsupported protocol causes error CURLE_UNSUPPORTED_PRO-
       TOCOL when libcurl  parses  a  schemeless  URL.  Parsing  happens  when
       curl_easy_perform(3)  or curl_multi_perform(3) is called. The protocols
       supported by libcurl will vary depending  on  how  it  was  built.  Use
       curl_version_info(3)  if you need a list of protocol names supported by
       the build of libcurl that you are using.

       This option does not change the default proxy protocol (http).

       Without this option libcurl would make a guess based on the  host,  see
       CURLOPT_URL(3) for details.

       The  application  does not have to keep the string around after setting
       this option.

DEFAULT
       NULL (make a guess based on the host)

PROTOCOLS
       All

EXAMPLE
       curl = curl_easy_init();
       if(curl) {
         /* set a URL without a scheme */
         curl_easy_setopt(curl, CURLOPT_URL, "example.com");

         /* set the default protocol (scheme) for schemeless URLs */
         curl_easy_setopt(curl, CURLOPT_DEFAULT_PROTOCOL, "https");

         /* Perform the request */
         curl_easy_perform(curl);
       }

AVAILABILITY
       Added in 7.45.0

RETURN VALUE
       CURLE_OK if the option is supported.

       CURLE_OUT_OF_MEMORY if there was insufficient heap space.

       CURLE_UNKNOWN_OPTION if the option is not supported.

SEE ALSO
       CURLOPT_URL(3),

libcurl 7.54.0                 December 21, 2016   CURLOPT_DEFAULT_PROTOCOL(3)