Set WordPress user display name

gistfile1.aw

<?php
require_once('./wp-load.php');

$all_users = get_users();

foreach( $all_users as $user ) {
	
	if ( $user->user_login == $user->display_name ) {
		$user_info = get_userdata( $user->ID );
		$new_display_name = $user_info->first_name . ' ' . $user_info->last_name;
		$args = array(
			'ID' => $user->ID,
			'display_name' => $new_display_name,
		);
		wp_update_user( $args );
		echo "Set $user->user_login as $new_display_name\n";
	} else {
		echo "$user->display_name already has a byline\n";
	}
}