<IfModule mod_rewrite.c>
  RewriteEngine on
  RewriteCond $1 !^(resources|system|application|ext)
  RewriteCond $1 !^([^\..]+\.php|robots\.txt)
  RewriteRule ^(.*)$ index.php/$1 [L]
</IfModule>    
<IfModule !mod_rewrite.c>
  ErrorDocument 404 index.php
</IfModule> 