nginx二级域名配置自动跳转到一级域名

nginx二级域名配置自动跳转到一级域名
rewrite配置内容：
 if ($http_host !~ "^www.aaa.com$") {
          rewrite  ^(.*)    http://www.aaa.com$1 permanent;
 }

下方，nginx代理访问项目proxy_pass，及rewrite参考
server
{
    listen 80;
    server_name www.aaa.com 100.100.100.100;
    location / {

        if ($http_host !~ "^www.aaa.com$") {
          rewrite  ^(.*)    http://www.aaa.com$1 permanent;
        }
        proxy_redirect off;
        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_pass http://192.168.1.2:8000;
    }
    access_log logs/aaa.com_access.log;
}