mod_rewrite - how to avoid infinite loop

I want to have a nice URLs on my website, so I have added this line into .htaccess, but it's causing infinite loop开发者_如何转开发.

RewriteRule ^(.*)$ http://www.mydomain.com/pages/$1%{QUERY_STRING}.php

It should rewrite every URL and add "pages/" and ".php" extension but only FIRST TIME not like some kind of recursive function.

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you don't need to pass the query string, that happens automatically.
see the documentation

other than that, try this

RewriteCond %{REQUEST_URI}  !^/pages/$
RewriteRule ^(/.*)? http://www.mydomain.com/pages/$1 [L]