Show Logged In User First Name Shortcode

gistfile1.txt

// Show Logged In User First Name Shortcode

function show_loggedin_function( $atts ) {

global $current_user, $user_login;
      get_currentuserinfo();
add_filter('widget_text', 'do_shortcode');
if ($user_login) 
return 'Welcome ' . $current_user->first_name . '!';
else
return '<a href="' . wp_login_url() . ' ">Login</a>';

}
add_shortcode( 'show_loggedin_as', 'show_loggedin_function' );