apache+codeigniter 通过.htcaccess做动态二级域名解析

AuthName "yousite Website Coming Soon..." //如果你想给你的网站加个权限访问 
AuthType Basic 
AuthUserFile D:/xxx/.htpasswd #如果你想设置密码访问 如何生成.htpasswd可以访问 http://www.htaccesstools.com/htpasswd-generator/ 
#AuthGroupFile /dev/null 
require valid-user 

<IfModule mod_rewrite.c> 
RewriteEngine On 
RewriteBase / 

#Removes access to the system folder by users. 
#Additionally this will allow you to create a System.php controller, 
#previously this would not have been possible. 
#'system' can be replaced if you have renamed your system folder. 
RewriteCond %{REQUEST_URI} ^system.* 
RewriteRule ^(.*)$ /index.php?/$1 [L] 

#When your application folder isn't in the system folder 
#This snippet prevents user access to the application folder 
#Submitted by: Fabdrol 
#Rename 'application' to your applications folder name. 
RewriteCond %{REQUEST_URI} ^application.* 
RewriteRule ^(.*)$ /index.php?/$1 [L] 


<IfModule mod_proxy.c> 
# Redirect to boutique (with any trailing path) 
RewriteCond %{HTTP_HOST} !^www. [NC] 
RewriteCond %{HTTP_HOST} ^([^.]+).yousite.com(.*)$ [NC] 
RewriteRule ^(.*)$ http://www.yousite.com/boutique/$1$2 [P,L] 
</IfModule> 

<IfModule !mod_proxy.c> 
# Redirect to boutique (with any trailing path) 
RewriteCond %{HTTP_HOST} !^www. [NC] 
RewriteCond %{HTTP_HOST} ^([^.]+).yousite.com(.*)$ [NC] 
RewriteRule ^(.*)$ http://www.yousite.com/boutique/%1/$1 [R=301,L] 
</IfModule> 

## Otherwise, force www; 
RewriteCond %{HTTP_HOST} ^yousite.com$ [NC] 
RewriteRule ^(.*)$ http://www.yousite.com/$1 [R=301,L] 

#Checks to see if the user is attempting to access a valid file, 
#such as an image or css document, if this isn't true it sends the 
#request to index.php 
RewriteCond %{REQUEST_FILENAME} !-f 
RewriteCond %{REQUEST_FILENAME} !-d 
RewriteRule ^(.*)$ index.php/$1 [L] 
</IfModule> 

<IfModule !mod_rewrite.c> 
# If we don't have mod_rewrite installed, all 404's 
# can be sent to index.php, and everything works as normal. 
# Submitted by: ElliotHaughin 

ErrorDocument 404 /index.php 
</IfModule> 

出处：cnblogs 微博:@草根小胡