apache_setenv() sets the value of the Apache environment variable specified by variable.
When setting an Apache environment variable, the corresponding $_SERVER variable is not changed.
The environment variable that's being set.
The new variable value.
Whether to set the top-level variable available to all Apache layers.
apache_setenv() can be paired up with apache_getenv() across separate pages or for setting variables to pass to Server Side Includes (.shtml) that have been included in PHP scripts.