nginx 实现所有的子域名301跳转到另外一个域名的对应子域名

server {
        listen 80;
        server_name *.olddomain.com;
        if ( $http_host ~* "^(.*?)\.olddomain\.com$"){
            set $domain $1;            
        }
        rewrite ^/(.*) http://$domain.newdomain.com/$1 permanent;
    }