I have a url http://www.example.com/images/thumbn...mequerystyring etc. that I want to exclude from a rewrite because it contans thumbnail.php

This works:
RewriteCond ${REQUEST_URI} !thumbnail

but this fails
RewriteCond ${SCRIPT_NAME} !thumbnail

isn't Script_name /thumbnail.php, and request_URI /thumbnail.php/?src-somequerystring

The both contain "thumbnail" so you would think they would both work

I found this:

but it doesn't hit any criteria where thumbnail would be modified into something different. Also, how do I get the computer to echo out request_uri and script_name so I can see what the computer actually think they are? Should we just show the $_SERVER vardump in php? or there something we can do right in htaccess?