[InvalidArgumentException] Command “build“ is not defined.

TP6 ， 在使用命令行

php think build demo 生成 应用目录 时报错
[InvalidArgumentException] Command "build" is not defined.

解决方法如下：

要先安装多应用扩展
composer require topthink/think-multi-app
如果扩展 安装补上，要把composer镜像地址改为官方文档内的镜像地址
composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/
在重新执行 composer require topthink/think-multi-app

之后在执行 php think build demo 返回结果是 success 则表示执行成功