how to redirect naked domains in apache to www

Question

i have multiple naked domains and i want to redirect those domains so that they begin with www.redirecteddomain.com. i have this .htaccess file which works with on domain how to generalize this ?

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

RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteRule ^.*$ index.php [NC,L]

Answer 1

I don't quite understand the question, but you want it to work for any domain to direct to the www. version?

This should work for that:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^([^\.]+\.[^\.]+)$
RewriteRule ^(.*)$ http://www.%1/$1 [R=301,L]

Answer 2

I find this slightly more readable

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]