When a user enters his login information and hits submit, i want to check if the user already exists or not. So, i have the following two questions 1. Which hook is needed to be implemented , for the case when user hits the submit button on the login form. I need the username entered by the user. 2. How to check if a user already exists in drupal or not programmatically ?
Some sample code would be really appreciated. Please help.
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