There are some subtleties in handling this sort of thing across different OS's. As you've indicated, using Windows file paths in Perl leads to lots of "synonymy" (different ways of expressing the same path: all-lower-case == mixed-case == all-upper-case, "\" == "/" ), whereas on linux and "traditional" unix, there is no such "synonymy": if two path strings differ in any way on any one character, they represent distinct paths/files.

And then there's the macosx adaptation of openBSD unix, where (in contrast to every other type of unix-based or unix-like OS I know of) case distinctions are ignored. I just tried this on my mac, and was quite saddened by the result:

$ echo foobar > /tmp/junk

$ cat /tmp/junk
foobar

$ cat /tmp/JUNK
foobar

$ echo hello > /tmp/JUNK

$ cat /tmp/junk
hello

$ cat /tmp/JUNK
hello
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I see that File::Spec has a "case_tolerant()" function, which (according to the man page) is supposed to return "a true or false value indicating, respectively, that alphabetic case is not or is significant when comparing file specifications."

But having tried that just now on macosx, I find that it returns false (case is significant), despite the fact that case is demonstrably not significant for distinguishing paths on macosx. I think that's something that needs to be fixed in File::Spec.

(I'm still using the Perl 5.8.8 that shipped with macosx 10.5.8 -- maybe this was fixed in Perl 5.10?)

So to succeed in your cross-platform intentions, you yourself have to check the value of $^O -- if it's "darwin", you have to fold case; if it's "MSWin32", you have to fold case and slashes; anything else, you leave all characters as-is.

(updated to fix link to module page)
(updated to change "mswin" to "MSWin32", which is what File::Spec looks for)