我编写了在页面运行时更新核心的代码。当我通过管理挂钩使用代码时，一切都正常admin_init 但当我将其添加到cron函数或通过任何前端挂钩运行它时，它不起作用（致命错误）init 或template_redirect 等

因此，我试图要求class-wp-upgrader.php 文件

add_action(\'init\', \'kit_wp_auto_update\'); // doesn\'t work
// add_action(\'admin_init\', \'kit_wp_auto_update\'); // works

    function kit_do_update(){
        require_once( ABSPATH . \'wp-admin/includes/class-wp-upgrader.php\' );

        fb(\'kit_do_update\');    


        $core_transient = get_site_transient( \'update_core\' );
        fb($core_transient);

        $updates = $core_transient->updates;
        $current = $updates[0];

        if( !empty( $core ) && $current->response == \'upgrade\' ){

            $skin = new Kit_Upgrader_Skin();        
            $upgrader = new Core_Upgrader($skin);
            $result = $upgrader->upgrade($current);

            if( is_wp_error( $result ) ) {
                return $result;
            }else{
                return true;
            }

        }
    }

Fatal error: Call to undefined function request_filesystem_credentials() in /home4/sisir/public_html/_sites/wpkitten.com/site/wp-admin/includes/class-wp-upgrader.php on line 1113

Questions:

1. request_filesystem_credentials() 在文件中定义，因此I don\'t understand why its undefined.Will wordpress have enough permission to do the upgrade?