域名如何跳转二级网站

RewriteEngine On
RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteRule ^(.*)$ http://sub.example.com/$1 [R=301,L]

server {
    listen 80;
    server_name example.com;

    location / {
        return 301 http://sub.example.com$request_uri;
    }
}

server {
    listen 80;
    server_name example.com;

    location / {
        proxy_pass http://sub.example.com;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

<?php
header('Location: http://sub.example.com' . $_SERVER['REQUEST_URI'], true, 301);
exit();
?>

const http = require('http');

http.createServer((req, res) => {
    res.writeHead(301, { 'Location': 'http://sub.example.com' + req.url });
    res.end();
}).listen(80);