Yes, the $^O variable is what you're looking for. (That's a caret and a capital o.) 
if ($^O =~ /Win32/i) {
  do this;
} else {
  do that;
}

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Head on over to perlvar to read more about this special variable.

In reply to Re: Porting code between NT/Unix by chipmunk
in thread Porting code between NT/Unix by Anonymous Monk

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