Check out modules File::Spec in the core distribution. These cope with many more file path syntaxes than Unix and Win32. For example: VMS

Device:[dir.subdir.subsubdir]file.ext;ver
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If you want your code to be truly portable (which is a good aim), you should be using modules such as File::Spec to handle the fine details of paths.

One thing to be careful of though is case sensitivity. Unix is case sensitive, whereas Win32 only pretends to be.