RewriteEngine On
  RewriteOptions Inherit
  RewriteRule ^/?([^/.]+)$  /$1/ [R]
  #RewriteCond %{REQUEST_FILENAME} !-d
  #RewriteRule ^/([^/.]+)/?$  /users/index.php?un=$1
  #RewriteCond %{REQUEST_FILENAME} !-f
  RewriteRule ^/([^/.]+)/?$  /users/index.php?un=$1  [L]