rewrite

 server {
    server_name www.xxx.com xxx.com;
    if ($host != 'www.xxx.com' ) {
        rewrite ^/(.*)$ http://www.xxx.com/$1 permanent;
    }
}

关键在 permanent

子目录跳转：

 location ~* ^/news/ {
    rewrite ^/news/(.*)$ http://www.xxx.com/old/news/$1 permanent;
}

 rewrite ^/(news|product)/(.*)$ /old/$1/$2 permanent last;

放server块里。随手写的，没测试。