Nginx配置无www域名转向带www域名

server
{
	listen       80;
	server_name  xxx.com www.xxx.com;
	index index.html index.php;
    root  /data/www/wwwroot;
    if ($http_host !~ "^www.xxx.com$") {
		rewrite  ^(.*)    http://www.xxx.com$1 permanent;
    }
	........................
}

server
{
listen 80;
server_name www.test.com test.com;
if ($host != 'www.test.com' ) {
    rewrite ^/(.*)$ http://www.test.com/$1 permanent;
}
........

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