etozhemaks 
тимоти 
M5_F90 
RewriteCond %{HTTP_HOST} ^site.ru$ [NC]
RewriteRule ^(.*)$ http://www.site.ru/$1 [R=301,L]
RewriteEngine On
RewriteCond %{HTTP_HOST} ^site.ru
RewriteRule (.*) http://www.site.ru/$1 [R=301,L]
Alllalo 
RewriteEngine on
RewriteCond %{ENV:HTTPS} on
RewriteRule .* - [E=SSL:s]
RewriteCond %{HTTP_HOST} !^www\.(.*) [NC]
RewriteRule .* http%{ENV:SSL}://www.%{HTTP_HOST}/$0 [R=301,L]