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/**
 * At login redirect processing
 * @param string $user_login
 * @param array $user
 */
function action_wp_login($user_login, $user) {
  if ( 'administrator' !== $user->roles[0] ) {
    wp_safe_redirect( home_url(), 301 );
    exit();
  }
}
add_action('wp_login', 'action_wp_login', 10, 2);