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.TH CURLOPT_ALTSVC 3 "5 Feb 2019" "libcurl 7.64.1" "curl_easy_setopt options"
.SH NAME
CURLOPT_ALTSVC \- set alt-svc cache file name
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ALTSVC, char *filename);
.fi
.SH EXPERIMENTAL
Warning: this feature is early code and is marked as experimental. It can only
be enabled by explicitly telling configure with \fB--enable-alt-svc\fP. You are
advised to not ship this in production before the experimental label is
removed.
.SH DESCRIPTION
Pass in a pointer to a \fIfilename\fP 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 a after a transfer, unless \fBCURLALTSVC_READONLYFILE\fP is set in
\fICURLOPT_ALTSVC_CTRL(3)\fP.

Specify a blank file name ("") to make libcurl not load from a file at all.
.SH DEFAULT
NULL. The alt-svc cache is not read nor written to file.
.SH PROTOCOLS
HTTPS
.SH EXAMPLE
.nf
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);
}
.fi
.SH AVAILABILITY
Added in 7.64.1
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_ALTSVC_CTRL "(3), " CURLOPT_CONNECT_TO "(3), " CURLOPT_RESOLVE "(3), "
.BR CURLOPT_COOKIEFILE "(3), "