Gets the value of an environment variable

Description

getenv(string $varname, bool $local_only = false): string|false

getenv(): array

Gets the value of an environment variable.

You can see a list of all the environmental variables by using phpinfo(). Many of these variables are listed within » RFC 3875, specifically section 4.1, "Request Meta-Variables".

Parameters

varname: The variable name.
local_only: Set to true to only return local environment variables (set by the operating system or putenv).

Return Values

Returns the value of the environment variable varname, or false if the environment variable varname does not exist. If varname is omitted, all environment variables are returned as associative array.

Changelog

Version	Description
7.1.0	The `varname` can now be omitted to retrieve an associative array of all environment variables.
7.0.9	The `local_only` parameter has been added.

Examples

Example #1 getenv() Example


<?php
// Example use of getenv()
$ip = getenv('REMOTE_ADDR');

// Or simply use a Superglobal ($_SERVER or $_ENV)
$ip = $_SERVER['REMOTE_ADDR'];

// Safely get the value of an environment variable, ignoring whether 
// or not it was set by a SAPI or has been changed with putenv
$ip = getenv('REMOTE_ADDR', true) ?: getenv('REMOTE_ADDR')
?>

Notes

Warning

If PHP is running in a SAPI such as Fast CGI, this function will always return the value of an environment variable set by the SAPI, even if putenv() has been used to set a local environment variable of the same name. Use the local_only parameter to return the value of locally-set environment variables.

getenv