.htaccess rewrite subdirectories to null

I want the browser location bar to show http://dir/ when I really am in http://dir/subdir/开发者_运维技巧subdir.

How do I do that? Thanks in advance!

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This will allow you to enter http://yourdomain.com/dir/ into your address bar and get the content that would normally be displayed for http://yourdomain.com/dir/subdir/subdir/:

RewriteEngine on
RewriteRule ^/dir /dir/subdir/subdir

Is this what you want? If not, please clarify.