.\" **************************************************************************
.\" *                                  _   _ ____  _
.\" *  Project                     ___| | | |  _ \| |
.\" *                             / __| | | | |_) | |
.\" *                            | (__| |_| |  _ <| |___
.\" *                             \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) 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_HSTS 3 "5 Feb 2019" "libcurl 7.74.0" "curl_easy_setopt options"
.SH NAME
CURLOPT_HSTS \- set HSTS cache file name
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTS, 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-hsts\fP. You are
advised to not ship this in production before the experimental label is
removed.
.SH DESCRIPTION
Make the \fIfilename\fP point to a file name to load an existing HSTS cache
from, and to store the cache in when the easy handle is closed. Setting a file
name with this option will also enable HSTS for this handle (the equivalent of
setting \fICURLHSTS_ENABLE\fP with \fICURLOPT_HSTS_CTRL(3)\fP).

If the given file does not exist or contains no HSTS entries at startup, the
HSTS cache will simply start empty. Setting the file name to NULL or "" will
only enable HSTS without reading from or writing to any file.

If this option is set multiple times, libcurl will load cache entries from
each given file but will only store the last used name for later writing.
.SH DEFAULT
NULL, no file name
.SH PROTOCOLS
HTTPS and HTTP
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_HSTS, "/home/user/.hsts-cache");
  curl_easy_perform(curl);
}
.fi
.SH AVAILABILITY
Added in 7.74.0
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_HSTS_CTRL "(3), " CURLOPT_ALTSVC "(3), " CURLOPT_RESOLVE "(3), "