如何覆盖用户在Drupal中登录的功能？

Question

I'm trying to change the user login form in drupal, I have created a variation of a theme in its own folder, now I try to change the functions associated to the login like the following:

function bartik_modificado_theme() {
return array(
'user_login' => array(
'arguments' => array('form' => NULL),
),
);
}
function bartik_modificado_form_id($form) {
$output.= drupal_render($form);
return $output; 
}

function bartik_modificado_user_login($form) {
$form['links']=t('');
$output.=drupal_render($form);
return $output; 
}

However I don't really know if the correct function to override is user_login (¿Where can I find that function in Drupal 7?) Currently the code doesn't work, please help.

Answer 1

Take a look at hook_form_alter at: https://api.drupal.org/api/drupal/modules%21system%21system.api.php/function/hook_form_alter/7

There is also an example for customizing user login forms by overriding the template and specific elements at:
http://www.wdtutorials.com/2012/05/16/drupal-7-how-customize-user-login-form#.UnNlepTXQ08