$config_dir
配置目录变量

This is the directory used to store config files used in the templates. Default is "./configs", meaning that it will look for the configs directory in the same directory as the executing php script.
该变量定义用于存放模板配置文件的目录,默认情况下,目录是:“./configs”,也就是说他将会在和php执行脚本相同的目录下寻找配置目录。

Technical Note: It is not recommended to put this directory under the web server document root.
技巧:不推荐把编译目录放在web服务器根目录下。