php - Why is my $_ENV empty?

Question

I'm running Apache/2.2.11 (Win32) PHP/5.3.0 and I did the following in my .htaccess file:

SetEnv FOO bar

If I print out the $_ENV variable in a PHP file, I get an empty array. Why doesn't my environment variable appear there? Why is it empty in the first place?

I did find my variable though, but it appears in the $_SERVER variable. And for some reason it appears twice, sort of. Why is this?

[REDIRECT_FOO] => bar
[FOO] => bar

It appears I can get it using getenv('FOO'), so maybe I should just use that instead. But I am still a bit curious to what causes this. Is this a Windows issue? Or what is going on?

Answer 1

Turns out there was two issues here:

1. $_ENV is only populated if php.ini allows it, which it doesn't seem to do by default, at least not in the default WAMP server installation.

; This directive determines which super global arrays are registered when PHP
; starts up. If the register_globals directive is enabled, it also determines
; what order variables are populated into the global space. G,P,C,E & S are
; abbreviations for the following respective super globals: GET, POST, COOKIE,
; ENV and SERVER. There is a performance penalty paid for the registration of
; these arrays and because ENV is not as commonly used as the others, ENV is
; is not recommended on productions servers. You can still get access to
; the environment variables through getenv() should you need to.
; Default Value: "EGPCS"
; Development Value: "GPCS"
; Production Value: "GPCS";
; http://php.net/variables-order
variables_order = "GPCS"

When I set the variables_order back to EGPCS, $_ENV is no longer empty.

2. When you use SetEnv in your .htaccess, it ends up in $_SERVER, not in $_ENV, which I gotta say is a tad confusing when it's named SetEnv...

# .htaccess
SetEnv ENV dev
SetEnv BASE /ssl/

# php
var_dump($_SERVER['ENV'], $_SERVER['BASE']);

// string 'dev' (length=3)
// string '/ssl/' (length=5)

3. The getenv function will always work and is not affected by the PHP setting for $_ENV Additionally it seems to do so insensitive to case, which might be useful.

var_dump(getenv('os'), getenv('env'));

// string 'Windows_NT' (length=10)
// string 'dev' (length=3)