Can someone help me with a rule that will redirect any url that begins with someDomain/catalog/product_info.php and have it redirect to the site's homepage?
If your site is e. g. example.com
and you want to redirect a request for http://example.com/catalog/product_info.php to http://example.com, you can do this (for Apache):
RewriteEngine On
RewriteRule ^catalog/product_info\.php$ / [R=301,L]
Keep in mind that an HTTP/301 redirect is a 'Site Moved Permenantly'; if this is temporary, use a 302, or just silently rewrite the URL without redirecting the HTTP client (omit the R=301
from the Rewrite Rule flags).