hide variable in url with htaccess

First I recommend you learn regex , yours is wrong ( and it works by "luck"):

[a-z,0-9,A-Z,-]

Within [...] do not use comma to separate, all values are detected, the correct would be something like:

RewriteRule ^(\d+)/categoria-([a-z0-9A-Z_\-]+)$ index.php?link=6&categoriaid=$1

Since the ID must be numeric, I have changed by \d

You can not hide the id that is between /<id>/categoria-<nome> , see the stackoverflow URLs themselves:

http://pt.stackoverflow.com/questions/164248/esconder-variavel-na-url-com-htaccess
http://pt.stackoverflow.com/questions/<id>/<nome>

Maybe you can use it like this:

http://site/categoria-teste-19
http://site/categoria-<nome>-<id>

Regex would look like this:

RewriteRule ^/categoria-([a-z0-9A-Z_\-]+)\-(\d+)$ index.php?link=6&categoriaid=$2

Jonnys, if you do not pass the information on the URL you can not get it to do the treatment in the .htaccess file, as was done in the example you gave.

If you want to have a custom URL without having to leave the explicit ID, consider using slugs, so you search for the slug rather than the ID.

The .htaccess would look something like this for the url www.com.br/categoria-teste:

RewriteEngine On
RewriteRule ^(.*)$ index.php?slug=$1 [L]