Drupal, user profiles: adding fields *only* editable by administrators

Question

I would like to add a field to user profiles that only administrator can use and change for each user.

In other words, it should be visible in users profiles but not editable by users (only by administrators).

I cannot do it with drupal permissions, right ?

thanks

Answer 1

With hook_form_alter you can set a permission on form fields. That way only users with the permission can edit it.

Example:

$form['example']['#access'] = user_access('permission');