// IF THE ip is NOT 1.2.3.4 then I want to use this:
RewriteEngine on
RewriteCond %{REQUEST_URI} !/triexa.png
RewriteCond %{REQUEST_URI} !/maintaince.php
RewriteRule !maintenance.php$ http://www.triexa.com/maintenance.php [R,L]

// IF THE IP IS 1.2.3.4 THEN I WANT TO USE THIS:
RewriteEngine on 
RewriteCond %{REQUEST_FILENAME} !-f 
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* process_url.php [L]