.\" **************************************************************************
.\" *                                  _   _ ____  _
.\" *  Project                     ___| | | |  _ \| |
.\" *                             / __| | | | |_) | |
.\" *                            | (__| |_| |  _ <| |___
.\" *                             \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
.\" * are also available at https://curl.se/docs/copyright.html.
.\" *
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
.\" * copies of the Software, and permit persons to whom the Software is
.\" * furnished to do so, under the terms of the COPYING file.
.\" *
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
.\" * KIND, either express or implied.
.\" *
.\" **************************************************************************
.\"
.TH CURLOPT_ALTSVC 3 "November 04, 2020" "libcurl 7.74.0" "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 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), "