execute function on cck submit

as we know that cck make form.
i want to do the following when the user press submit in CCK it exec a Perl script, so how could i join between the submit form and the exec function, and also i need to exec different function on different cck, for example i made a cck for create category, when i press submit it should exec a function, on the other hand i create a cck for products, so when submitting it should exec the function of product not the category one, so what is the way to do that.
thanx a lot
i wish you understand my point.
i don't want to teach me how to write the perl function, because i have already wrote it, i just want the drupal function which can be used on CCk to execute the outside function.
thanx alot