How to do a RewriteRule for multiple file extensions as .(html|htm|php)?

How to do a RewriteRule 开发者_运维技巧like this, for multiple file extensions as .(html|htm|php)?

RewriteRule ^(/)?$ directory/index.php [L] 

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This will redirect anything that ends with .html, .htm or .php to directory/index.php

RewriteRule ^(.*\.(html|htm|php))$ directory/index.php [L]