subdomain redirection using htaccess

I need to redirect the url http://testing.dom开发者_如何学Cain.com/ to http://testing.domain.com/admin/index.php

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I think you are trying to secure your home page. Put this php code in your index.php.

header("Location: http://testing.domain.com/admin/index.php")  
exit;

If you got everything in admin folder, then you can use this one

Options -Indexes
RewriteEngine on                   
RewriteCond $1 !^(admin)
RewriteRule ^(.*)$ admin/index.php [L]

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Put the following into your .htaccess file

Redirect 301 http://testing.domain.com/ http://testing.domain.com/admin/index.php