域名如何指向二级目录

<VirtualHost *:80>
    ServerName example.com
    DocumentRoot /var/www/example

    <Directory /var/www/example>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>
</VirtualHost>

<VirtualHost *:80>
    ServerName sub.example.com
    DocumentRoot /var/www/sub

    <Directory /var/www/sub>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
    </Directory>
</VirtualHost>

server {
    listen 80;
    server_name example.com;
    root /var/www/example;
    index index.html index.htm;

    location / {
        try_files $uri $uri/ =404;
    }
}

server {
    listen 80;
    server_name sub.example.com;
    root /var/www/sub;
    index index.html index.htm;

    location / {
        try_files $uri $uri/ =404;
    }
}