It seems to me like a bug in the ActiveState Perl path separator translation. I don't know if it has been fixed on later versions of ActiveState Perl releases, but my version 5.8.0 does not seem to translate the / path separator in `` or qx to \. And I was getting incorrect command format errors.

There are many work arounds. The method I prefer is to use the Win32::AbsPath module that comes with your ActiveState perl installation to normalize the pathnames into native Windows format.

use strict;
if ($^O eq "MSWin32") {
  require Win32::AbsPath;  # load Win32::AbsPath if under Windows
}

sub NormalizePath          # normalize/fix the path
{                          # if on a Windows platform
  my $path = shift;
  $path = Win32::AbsPath::Fix $path if $^O eq "MSWin32";
  return $path;
}

my $command = NormalizePath('C:/Windows/System32/cmd.exe');
my $dir = `$command /C dir`;

print "$dir";
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Update: jacques below has mentioned about File::Spec::Functions, which is a cleaner approach than using Win32::AbsPath. Here's an example using the File::Spec::Functions module -

use strict;
use File::Spec::Functions;

my $command = canonpath('C:/Windows/System32/cmd.exe');
my $dir = `$command /C dir`;
print $dir;
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