1.重定向domain.com到www.domain.com
这种重定向旨在使域名唯一，是网站SEO必须要做的，后面重定向www.domain.com到domain.com也是出于同样的原因，只是形式不同。
打开.htaccess文件，加入以下规则。(下面的规则是针对主域名的，子域名要修改)

RewriteEngine On
RewriteBase /
RewriteCond %{http_host} ^domain.com [NC]
RewriteRule ^(.*)$ http://www.domain.com/$1 [L,R=301]

2.重定向www.domain.com到domain.com

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^www.domain.com$ [NC]
RewriteRule ^(.*)$ http://domain.com/$1 [L,R=301]

3.重定向olddomain.com到www.newdomain.com

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} !olddomain.com$ [NC]
RewriteRule ^(.*)$ http://www.newdomain.com/$1 [L,R=301]

4.重定向olddomain.com to newdomain.com

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} !olddomain.com$ [NC]
RewriteRule ^(.*)$ http://newdomain.com/$1 [L,R=301]

5.全部重定向到newdomain

Options +FollowSymLinks
RewriteEngine on
RewriteRule ^(.*)$ http://www.b2cmarts.com/$1 [L,R=301]

6.重定向domain.com/file/file.php 到 otherdomain.com/otherfile/other.php

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^www.domain.com$
RewriteRule ^file/file.php$ http://www.otherdomain.com/otherfile/other.php [R=301,L]