.htaccess detect subdomain

[jimmymm]

I have a few folders that need to act differently depending on whether they are accessed from the root domain or a subdomain. I basically need .htaccess to do something like:

if(sub.domain.com)
do something
else if(domain.com)
do something else

Is this possible with .htacces?

Thanks in advance

[g1smd]

RewriteCond %{HTTP_HOST} ^....
RewriteRule .... .... [L]

[lucy24]

Better come back and explain in English what you mean by "accessed from", because my answer would have involved %{HTTP_REFERER}.


:: memo to self: figure out how to expand MSIE 6 exception to allow people to visit more than one page without opening the door to auto-referring robots ::

[jimmymm]

In a nutshell, I work on local folders for pre-release site testing. My live site (domain.com) is always pointed to a folder named AALIVE, while my #1 test site (test.domain.com) points to AATEST1. When testing is complete I have a script that renames AALIVE->OLDx, and AATEST1->AALIVE, effectively setting the test site as live while maintaining the old site in case I have to revert.

I just realized that google has indexed my test domains, which I am trying to stop. My thought was to identify whether the folder was being accessed from domain.com or test.domain.com, and allow only my ip for the test site.

I am open to suggestions to help sort this out... any thoughts will be greatly appreciated!

[jimmymm]

After much research I think I need to use something like the following:

SetEnvIf HOST ^*test.*$ HOST_TEST

<IfDefine HOST_TEST>
AuthUserFile …
</IfDefine>

This should set the environment variable HOST_TEST if the subdomain consists of test, then require authentication. However, I'm sure I have something wrong as I'm getting an internal server error, and would appreciate a second set of eyes.