(PHP 3, PHP 4, PHP 5)
Returns the value of the environment variable varname, or FALSE on an error.
<?php// Example use of getenv()$ip = getenv('REMOTE_ADDR');// Or simply use a Superglobal ($_SERVER or $_ENV)$ip = $_SERVER['REMOTE_ADDR'];?>
You can see a list of all the environmental variables by using phpinfo(). You can find out what many of them mean by taking a look at the CGI specification, specifically the page on environmental variables.
See also putenv(), apache_getenv() and Superglobals.