RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]
to reverse redirect a domain from a www to a non www
RewriteEngine On
RewriteCond %{HTTP_HOST} !^my-domain\.com$ [NC]
RewriteRule ^(.*)$ http://my-domain.com/$1 [R=301,L]
Another way using the conf
redirect permanent / https://insert-url-of-your-site/
Example of using multiple url to point to the same site
ServerName domain1.net
DocumentRoot /opt/rlcache/www/moodle_prod
Alias /sandbox /opt/rlcache/www/moodle_sand
ServerName domain2.net
Redirect permanent / http://domain1.net/