how to redirect http://domain.com to http://www.domain.com permanently

Hello there,
I somewhere learned here on DP that you can permanent redirect the http:/domain.com to http:/www.domain.com through .htaccess
but i dont know the exact rule of that
Would anyone please give me that rule to write the above mentioned situation

Thanx

 

try


RewriteEngine on

RewriteCond %{HTTP_HOST} !^www\.domain\.com [NC]
RewriteCond %{HTTP_HOST} !^$
RewriteRule ^(.*) http://www.domain.com/$1 [L,R=301]

 

RewriteBase /
RewriteCond %{HTTP_HOST} !^www\.domain\.com [NC]
RewriteRule ^(.*) http://www.domain.com/$1 [L,R=301]

Code (markup):

in your .htaccess