[quote author=مجید link=topic=16274.msg86223#msg86223 date=1220991397]
کد:
RewriteEngine On
Options +FollowSymlinks
RewriteBase /
RewriteCond %{HTTP_HOST} 2nddomain.com
RewriteCond %{REQUEST_URI} !subfolder/
RewriteRule ^(.*)$ subfolder/$1 [L]

[/quote]

از کد بالا استفاده کن