Adding www to a url
From Joomla! Documentation
How Do I Get www as a Prefix in All My Joomla! Sites?[edit]
Add the following to your .htaccess file:
RewriteEngine On
RewriteCond %{HTTP_HOST} !^(www\.example\.com)?$
RewriteRule (.*) http://www.example.com/$1 [R=301,L]A more complete solution fixing several other canonicalisation issues at the same time:
RewriteEngine On
#
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^/]+/)*index\.html?\ HTTP/
RewriteRule ^(([^/]+/)*)index\.html?$ http://www.example.com/$1 [R=301,L]
#
RewriteCond %{THE_REQUEST} !^POST
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^/]+/)*index\.php\ HTTP/
RewriteCond %{SERVER_PORT}>s ^(443>(s)|[0-9]+>s)$
RewriteRule ^(([^/]+/)*)index\.php$ http%2://www.example.com/$1 [R=301,L]
#
RewriteCond %{HTTP_HOST} !^(www\.example\.com)?$
RewriteRule (.*) http://www.example.com/$1 [R=301,L]