All the following scenarios will require you to edit the .htaccess file in your root directory. Htaccess is an optional configuration file used by Apache to handle all incoming requests. You will also need support for mod_rewrite.

Redirecting example.com to www.example.com

The reason for doing this is because, by default, you will have 2 distinct URLs for each page on your website. For example http://www.example.com/download/games.html and http://example.com/download/games.html are one and the same page. Unfortunately search engines assume that they are completely distinct. Some say this will trigger the so-called duplicated content filter or that pagerank may spread across too many pages.

The solution is to redirect one url to the other with the response code 301. I will just use the non-www to www redirection in this article. You need a rule that will be applyable to all the URLs on your website.

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

This code will find all requests that contain the host example.com and redirect them using a 301 code to www.example.com. The best part is that any string after the host is taken care of. In other words, http://example.com/page1.html will be redirected to http://www.example.com/page1.html.

Redirecting a subfolder to the subdomain

When you add a new subdomain in cPanel, a folder with the same name is created in your root directory. This is where all the files directly accessible from the subdomain are located. The downside is that you now have 2 ways of viewing the same file: http://www.example.com/subdomain/page.html and http://subdomain.example.com/page.html. This is not as crucial as the scenario previously discussed because the chances of someone linking to your “subdomain” folder are pretty slim. However, we are really into eliminating every duplicated URL out there so we will deal with this problem too :).

RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
RewriteCond %{REQUEST_URI} ^/subdomain(.*)$ [NC]
RewriteRule ^subdomain/(.*)$ http://subdomain.example.com/$1 [L,R=301]

Having these lines in .htaccess will make sure that http://www.example.com/subdomain/page.html will redirect to http://subdomain.example.com/page.html. But we still have http://example.com/subdomain/page.html which is not redirected. So what now?

Combine them both!

RewriteEngine on
RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
RewriteCond %{REQUEST_URI} ^/subdomain(.*)$ [NC]
RewriteRule ^subdomain/(.*)$ http://subdomain.example.com/$1 [L,R=301]

You are now fully covered!

• http://example.com redirects to http://www.example.com
• http://example.com/somepage.html redirects to http://www.example.com/somepage.html
• http://www.example.com/subdomain/ redirects to http://subdomain.example.com/
• http://www.example.com/subdomain/somepage.html redirects to http://subdomain.example.com/somepage.html
• http://example.com/subdomain/somepage.html redirects to http://www.example.com/subdomain/somepage.html which redirects to http://subdomain.example.com/somepage.html