RewriteEngine on
RewriteCond %{REQUEST_URI} !^products\.php$
RewriteRule ^([^/]+)/?$ products.php?show=cats&main_category=$1






==================================================================================
tester@ts1:~$ tail /var/log/apache2/rewrite.log 
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#827ed78/initial] (3) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] add per-dir prefix: products.php -> /var/www/jameswhitepools/poolchemicalsonline/products.php
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#827ed78/initial] (2) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] strip document_root prefix: /var/www/jameswhitepools/poolchemicalsonline/products.php -> /jameswhitepools/poolchemicalsonline/products.php
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#827ed78/initial] (1) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] internal redirect with /jameswhitepools/poolchemicalsonline/products.php [INTERNAL REDIRECT]
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#828c398/initial/redir#1] (3) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] strip per-dir prefix: /var/www/jameswhitepools/poolchemicalsonline/products.php -> products.php
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#828c398/initial/redir#1] (3) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] applying pattern '^([^/]+)/?$' to uri 'products.php'
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#828c398/initial/redir#1] (4) RewriteCond: input='/jameswhitepools/poolchemicalsonline/products.php' pattern='!^products\.php$' => matched
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#828c398/initial/redir#1] (2) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] rewrite products.php -> products.php?show=cats&main_category=products.php
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#828c398/initial/redir#1] (3) split uri=products.php?show=cats&main_category=products.php -> uri=products.php, args=show=cats&main_category=products.php
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#828c398/initial/redir#1] (3) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] add per-dir prefix: products.php -> /var/www/jameswhitepools/poolchemicalsonline/products.php
10.0.0.134 - bcl [29/Mar/2007:12:46:44 +0100] [10.0.0.159/sid#813ccc8][rid#828c398/initial/redir#1] (1) [per-dir /var/www/jameswhitepools/poolchemicalsonline/] initial URL equal rewritten URL: /var/www/jameswhitepools/poolchemicalsonline/products.php [IGNORING REWRITE]