Passing envirnoment variables to PHP

[mammal]

Is it possible to pass an environment variable to a php script?

I'm trying this

RewriteRule a.php /b.php [E=APACHE_REDIR:YES]

but APACHE_REDIR is not present in $_ENV in b.php

I'll be redirecting in Apache and I need to be able to tell in the script, whether it's accessed directly, or indirectly through Apache's internal redirection

Thanks for a response

Regards,
Stan

[mammal]

nevermind... I've just found out

it has to be accessed through getenv() function rather than $_ENV