htaccess for subdomain

I need a .htaccess file: the file will rewrite rule for:

x开发者_Python百科yz.sitename.com will be rewritten as: sitename.com/index.php/a/b/xyz

xyz.sitename.com/m/n/o will be rewritten as: sitename.com/index.php/m/n/o/xyz

sitename.com/m/n/o will be rewritten as: sitename.com/index.php/m/n/o

---

Options +FollowSymlinks
RewriteEngine on
RewriteRule (.+).sitename.com/ sitename.com/index.php/a/b/$1
RewriteRule (.+).sitename.com/(.+) sitename.com/$2/$1

See .htaccess trips and tips.

---

Try this:

RewriteEngine On

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{HTTP_HOST} ^www [OR]
RewriteCond /%{HTTP_HOST} ^(/[^\.]+)\.[^\.]+\.[^\.]+$
RewriteRule ^.*$ /index.php/$0%1

Although, as I've mentioned in another answer, trying to create PATH_INFO with mod_rewrite seems to be a little problematic. You might have better luck, but take the alternatives of writing the path to a query string or using $_SERVER variables to get this information into consideration.