目前apache伪静态URL重写.htaccess里是下面规则：
http://www.abc.com ---> index.php
http://www.abc.com/late/ ---> ./filedir/late.php?p=1
http://www.abc.com/popular/ ---> ./filedir/popular.php?p=1
http://www.abc.com/down/name-id/ ---> ./filedir/detail.php?id=number
http://www.abc.com/cat/catname-catid/ ---> ./filedir/cat.php?catid=number

http://www.abc.com/bb ---> ./filedir/bb.php
http://www.abc.com/bblate/ ---> ./filedir/bblate.php?p=1
http://www.abc.com/bbpopular/ ---> ./filedir/bbpopular.php?p=1
http://www.abc.com/bdown/name-id/ ---> ./filedir/bbdetail.php?id=number
http://www.abc.com/bcat/bcatname-catid/ ---> ./filedir/bbcat.php?bbcat.php?catid=number

现要增加一个二级域名bb.abc.com也指向www.abc.com服务器，并将域名后路径改为和www.abc.com形式相同，即
http://bb.abc.com ---> ./filedir/bb.php
http://bb.abc.com/late/ ---> ./filedir/bblate.php?p=1
http://bb.abc.com/popular/ ---> ./filedir/bbpopular.php?p=1
http://bb.abc.com/down/name-id/ ---> ./filedir/bbdetail.php?id=number
http://bb.abc.com/cat/bcatname-catid/ ---> ./filedir/bbcat.php?bbcat.php?catid=number

这要如何写.htaccess的URL重写规则呢？根据判断域名显示不同内容