apache - Environment variables - htaccess and php -

i need little environment variables. after setup variable in .htaccess file this:

setenv statusv "online" 

how can change variable value permanently (global scope) using php. if change variable value this:

apache_setenv("statusv", "offline");  

or

putenv('statusv=offline'); 

variable changed , exists in session changed it.

what want forbid clients access files via direct url if environment variable set specific value.

i appreciate every , thank in advance.