centos 上搭建报错未定义__PUBLIC__ 这是为什么啊，求大神帮忙看看


Use of undefined constant __PUBLIC__ - assumed '__PUBLIC__' (this will throw an Error in a future version of PHP)
<?php
return [
// 视图输出字符串内容替换
'view_replace_str' => [
'__PUBLIC__' => __PUBLIC__,//public目录的全局变量，在/public/home.php中定义
'__STATIC__' => __PUBLIC__. '/static',
'__ADMIN__' => __PUBLIC__. '/static/admin',
'__HOME__' => __PUBLIC__. '/static/home',
],
];