CURLOPT_ALTSVC(3)          Library Functions Manual          CURLOPT_ALTSVC(3)

NAME
       CURLOPT_ALTSVC - alt-svc cache filename

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ALTSVC, char *filename);

DESCRIPTION
       Pass in a pointer to a filename to instruct libcurl to use that file as
       the Alt-Svc cache to read existing cache contents from and possibly
       also write it back to after a transfer, unless CURLALTSVC_READONLYFILE
       is set in CURLOPT_ALTSVC_CTRL(3).

       Specify a blank filename ("") to make libcurl not load from a file at
       all.

DEFAULT
       NULL. The alt-svc cache is not read nor written to file.

PROTOCOLS
       HTTP

EXAMPLE
       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           curl_easy_setopt(curl, CURLOPT_ALTSVC_CTRL, CURLALTSVC_H1);
           curl_easy_setopt(curl, CURLOPT_ALTSVC, "altsvc-cache.txt");
           curl_easy_perform(curl);
         }
       }

FILE FORMAT
       A text based file with one line per alt-svc entry and each line
       consists of nine space-separated fields.

       An example line could look like

       h2 www.example.com 8443 h3 second.example.com 443 "20190808 06:18:37" 1 0

       The fields of that line are:

       h2     ALPN id for the source origin

       www.example.comp
              Hostname for the source origin

       8443   Port number for the source origin

       h3     ALPN id for the destination host

       second.example.com
              Hostname for the destination host

       443    Port number for the destination host

       2019*  Expiration date and time of this entry within double quotes. The
              date format is "YYYYMMDD HH:MM:SS" and the time zone is GMT.

       1      Boolean (1 or 0) if "persist" was set for this entry

       0      Integer priority value (not currently used)

AVAILABILITY
       Added in 7.64.1

RETURN VALUE
       Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
       if not.

SEE ALSO
       CURLOPT_ALTSVC_CTRL(3), CURLOPT_CONNECT_TO(3), CURLOPT_COOKIEFILE(3),
       CURLOPT_RESOLVE(3)

libcurl                          April 26 2024               CURLOPT_ALTSVC(3)