NAME

       curl_global_trace - Global libcurl logging configuration

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_global_trace(const char *config);

DESCRIPTION

       This  function  configures  the logging behavior, allowing to make some parts of curl more
       verbose or silent than others.

       This function may be called during the initialization phase of a program. It does not have
       to  be.  It  can  be  called several times even, possibly overwriting settings of previous
       calls.

       Calling  this  function  after  transfers  have  been  started  is  undefined.   On   some
       platforms/architectures it might take effect, on others not.

       This  function  is  thread-safe  since  libcurl  8.3.0  if  curl_version_info(3)  has  the
       CURL_VERSION_THREADSAFE feature bit set (most platforms).

       If this is not thread-safe, you must not call this function when any other thread  in  the
       program  (i.e.  a  thread sharing the same memory) is running.  This does not just mean no
       other thread that is using libcurl. Because  curl_global_init(3)  may  call  functions  of
       other  libraries that are similarly thread unsafe, it could conflict with any other thread
       that uses these other libraries.

       If you are initializing libcurl from a Windows DLL  you  should  not  initialize  it  from
       DllMain or a static initializer because Windows holds the loader lock during that time and
       it could cause a deadlock.

       The config string is a list of comma-separated component names. Names are case-insensitive
       and unknown names are ignored. The special name "all" applies to all components. Names may
       be prefixed with '+' or '-' to enable or disable detailed logging for a component.

       The list of component names is not part of curl's  public  API.  Names  may  be  added  or
       disappear  in  future  versions  of  libcurl.  Since  unknown  names are silently ignored,
       outdated log configurations does not cause errors when upgrading libcurl. Given that, some
       names can be expected to be fairly stable and are listed below for easy reference.

       Note  that log configuration applies only to transfers where debug logging is enabled. See
       CURLOPT_VERBOSE(3) or CURLOPT_DEBUGFUNCTION(3) on how to control that.

TRACE COMPONENTS

       tcp    Tracing of TCP socket handling: connect, reads, writes.

       ssl    Tracing of SSL/TLS operations, whichever SSL backend is used in your build.

       http/2 Details about HTTP/2 handling: frames, events, I/O, etc.

       http/3 Details about HTTP/3 handling: connect, frames, events, I/O etc.

       http-proxy
              Involved when transfers are tunneled through a HTTP proxy. "h1-proxy" or "h2-proxy"
              are also involved, depending on the HTTP version negotiated with the proxy.

              In  order  to  find  out  all  components involved in a transfer, run it with "all"
              configured. You can then see all names involved in  your  libcurl  version  in  the
              trace.

EXAMPLE

       int main(void)
       {
         /* log details of HTTP/2 and SSL handling */
         curl_global_trace("http/2,ssl");

         /* log all details, except SSL handling */
         curl_global_trace("all,-ssl");
       }

       Below  is  a  trace  sample  where "http/2" was configured. The trace output of an enabled
       component appears at the beginning in brackets.
       * [HTTP/2] [h2sid=1] cf_send(len=96) submit https://example.com/
       ...
       * [HTTP/2] [h2sid=1] FRAME[HEADERS]
       * [HTTP/2] [h2sid=1] 249 header bytes
       ...

AVAILABILITY

       Added in 8.3

RETURN VALUE

       If this function returns non-zero, something went wrong and the configuration may not have
       any effects or may only been applied partially.

SEE ALSO

       curl_global_init(3), libcurl(3)