curl/docs/cmdline-opts/hsts.md

c	SPDX-License-Identifier	Long	Arg	Protocols	Help	Added	Category	Multi	See-also	Example
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.	curl	hsts	<filename>	HTTPS	Enable HSTS with this cache file	7.74.0	http	append	proto	--hsts cache.txt $URL

--hsts

Enable HSTS for the transfer. If the filename points to an existing HSTS cache file, that is used. After a completed transfer, the cache is saved to the filename again if it has been modified.

If curl is told to use HTTP:// for a transfer involving a hostname that exists in the HSTS cache, it upgrades the transfer to use HTTPS. Each HSTS cache entry has an individual lifetime after which the upgrade is no longer performed.

Specify a "" filename (zero length) to avoid loading/saving and make curl just handle HSTS in memory.

You may want to restrict your umask to prevent other users on the same system to access the created file.

If this option is used several times, curl loads contents from all the files but the last one is used for saving.