Redirect all domain aliases to main domain?

[georgec]

Hi:
I'm looking to redirect all domain aliases of our site to the primary domain, obviously honoring any query strings, sub paths etc. However, I also wish to honor the presence of "www" or lack thereof entered into the alias, which the code below doesn't do:

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

How can I get the redirect to check whether the alias entered contains the "www" part, and redirect to the exact same version on the main domain?

Thanks!

[g1smd]

Does

example.com

and

www.example.com

serve the same content?

If they do, you should redirect all requests to the www version, so as to avoid this Duplicate Content issue.

[jdMorgan]

If the www and non-www contain different content, then

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

should do.

Jim