Force Subdomain
If you have setup a subdomain and want to ensure that all visitors are viewing a particular part of your site through the subdomain, you can insert the following code in your htaccess file:
RewriteCond %{HTTP_HOST} !^$
RewriteCond %{HTTP_HOST} !^subdomain.example.com$ [NC]
RewriteRule ^/(.*)$ http://subdomain.example.com/$1 [L,R=301]
RewriteCond %{HTTP_HOST} !^subdomain.example.com$ [NC]
RewriteRule ^/(.*)$ http://subdomain.example.com/$1 [L,R=301]
