Linux系统下，修改文件httpd.conf或者.htaccess文件保存即可，例如：
RewriteEngine OnRewriteCond %{HTTP_HOST} ^xxxx.com [NC]RewriteRule ^(.*)$ http://www.xxxx.com/$1 [L,R=301]
RewriteEngine On
RewriteCond %{HTTP_HOST} ^xxxx.com [NC]
RewriteRule ^(.*)$ http://www.xxxx.com/$1 [L,R=301]
