PHP & STDOUT

000-stdout.php

#!/usr/bin/env php
<?php
var_dump(defined('STDOUT'));
var_dump(@fopen('php://stdout', 'w'));

001-result.sh

## PHP 5.3.15

$ php ./stdout.php
# bool(true)
# resource(5) of type (stream)

$ curl -s file://`pwd`/stdout.php | php
# bool(false)
# resource(2) of type (stream)

## PHP 5.4.5

$ php ./stdout.php
# bool(true)
# resource(5) of type (stream)

$ curl -s file://`pwd`/stdout.php | php
# bool(false)
# resource(2) of type (stream)

$ echo '<?php var_dump(defined("STDOUT"));' | php
# bool(false)

I do not get your problem. http://php.net/manual/en/features.commandline.io-streams.php clearly says These constants are not available if reading the PHP script from stdin.

Note: that page is the second result for https://www.google.com/search?complete=0&q=php+stdout

I read these pages but I was asking what is the point of this behavior ?
Piping to PHP means that it does not have an actual STDOUT ?