php-cli: What is the best way to detect the hosting OS?

I have a script which I want to run on windows under Cygwin and on Linux. I have to make distinction between the two running e开发者_开发技巧nvironment for some purposes. What is the best way to do it?

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There is a pre-defined constant PHP_OS which will help, but only displays the OS that PHP was built on, not the OS it is running on.

php_uname is what you want to discover information about the current server running your code:

php_uname() returns a description of the operating system PHP is running on.

Specifically,

php_uname('s'); // Operating system name. eg. FreeBSD. 

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how about the PHP_OS variable?

print PHP_OS;