#例访问路径 http://127.0.0.1/mall/a.php
location /mall/ {
    alias D:/web/mall/public/;

    location ~ \.php$ {
        # 此时
        # $document_root 为 D:/web/mall/public/
        # $fastcgi_script_name 为 /mall/a.php
        # 如果SCRIPT_FILENAME直接用$fastcgi_script_name，实际寻找路径会成为D:/web/mall/public/mall/a.php

        set $real_script_name $fastcgi_script_name;
        if ($fastcgi_script_name ~* "/mall/(.+\.php)$") {
            set $real_script_name $1;
        }

        fastcgi_pass   127.0.0.1:20074; #此处根据自己实际配置，我的是宝塔环境php7.4
        fastcgi_index  index.php;
        fastcgi_param  SCRIPT_FILENAME $document_root$real_script_name;
        include        fastcgi_params;
    }

}