如何在子文件夹中设置CodeIgniter htaccess？

I have setup a CodeIgniter Application on my server at the following URL:

http://subdomain.domainame.com/something1/something2/

(I have used something1 and something 2 as examples)

Now, I can access the application perfectly fine when using the above URL and can add /index.php/controller/action etc to the end.

I have tried to setup a .htaccess file in the same directory the application is hosted but it doesn't seem to be working.

The .htaccess file contains the following:

RewriteEngine on
RewriteCond $1 !^(index\.php|images|robots\.txt)
RewriteRule ^(.*)$ something1/something2/index.php?/$1 [L]

This is giving me a 500 Internal Server Error.

Can anyone shed some light on this?

I think I might have solved this.

Changed:

RewriteRule ^(.*)$ something1/something2/index.php?/$1 [L]

To:

RewriteRule ^(.*)$ /something1/something2/index.php?/$1 [L]

I am no longer getting an internal server error.

In order to assist anyone coming across this question, here is my full .htaccess file:

RewriteEngine on
RewriteCond $1 !^(index\.php|images|robots\.txt)
RewriteRule ^(.*)$ /something1/something2/index.php?/$1 [L]