redirect subdir with htaccess

I need 开发者_运维百科to redirect this way:

http://domain.com/XXXXXX (6 chars letters and numbers);

to:

http://domain.com/coupon/XXXXXX 

and keep url like above.

Any idea?

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Try this:

RewriteEngine On
RewriteRule ^([\w\d]{6})\/?$ /coupon/$1/