How can I tell if my Perl script is running under Windows?

Question

What is the best way to programatically determine if a Perl script is executing on a Windows based system (Win9x, WinXP, Vista, Win7, etc.)?

Fill in the blanks here:

my $running_under_windows = ... ? 1 : 0;

Answer 1

From perldoc perlvar:

• $OSNAME
• $^O

The name of the operating system under which this copy of Perl was built, as determined during the configuration process. The value is identical to $Config{'osname'}. See also Config and the -V command-line switch documented in perlrun.

In Windows platforms, $^O is not very helpful: since it is always MSWin32 , it doesn't tell the difference between 95/98/ME/NT/2000/XP/CE/.NET. Use Win32::GetOSName() or Win32::GetOSVersion() (see Win32 and perlport) to distinguish between the variants.

Answer 2

$^O eq 'MSWin32'

(Source: The perlvar manpage)

Answer 3

Use Devel::CheckOS. It handles all of the logic and special cases for you. I usually do something like:

use Devel::CheckOS qw(die_unsupported os_is);

die "You need Windows to run this program!" unless os_is('MicrosoftWindows');

The 'MicrosoftWindows' families knows about things such as Cygwin, so if you are on Windows but not at the cmd prompt, os_is() will still give you the right answer.