(PHP 4, PHP 5, PHP 7, PHP 8)
putenv — Sets the value of an environment variable
Adds assignment
to the server environment. The environment variable will only exist for the duration of the current request. At the end of the request the environment is restored to its original state.
assignment
The setting, like "FOO=BAR"
Example #1 Setting an environment variable
<?php
putenv("UNIQID=$uniqid");
?>