Forcing HTTPS with .HTaccess

To force all web traffic to use HTTPS:

RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.example.com/$1 [R,L]

RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

To force a specific domain to use HTTPS:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^example\.com [NC]
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://www.example.com/$1 [R,L]

To force SSL on a specific directory:

RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteCond %{REQUEST_URI} directory_name
RewriteRule ^(.*)$ https://www.example.com/directory_name/$1 [R,L]