htaccess question

I know it's not a php question, but I can't readily find the answer elsewhere.

I want to make this directive universal. Put htaccess file on any host in any folder.

This works
RewriteEngine On

RewriteCond %{SERVER_PORT} !=443

RewriteRule ^(.*)$ https://www.foo.org/bar/$1 [R=301,L]  #Here the foo.org and /bar must be specified

I want what is in effect

RewriteRule ^(.*)$ https://{host_name}/{directory}/$1 [R=301,L]

I can easily do this with php regex capturing the (host and dir) and then rewriting the text string; but the Apache 
directives are not obvious.