nginx和apache：配置301跳转（实现自动加www前缀）

例：
server {
listen       80 default;
server_name  www.test.com test.com;
location / {
root   /data/webroot/test;
index index.html;
if ($host !~* ^www) {
set $name_www www.$host;
rewrite ^(.*)$ http://$name_www$1 permanent;
}
}
｝

<VirtualHost *:80>
ServerAdmin webmaster@dummy-host.example.com
DocumentRoot "/data/webroot/test"
ServerName test.com
ServerAlias www.test.com
RewriteEngine on
RewriteCond %{HTTP_HOST} ^test.com  [NC]
RewriteRule ^(.*)$ http://www.test.com$1 [R=permanent,L]
</VirtualHost>