Well, you can special-case it, but then it'll only work for .tar.gz: 
s{\.(?:tar\.gz|[^.]+)\z}{};

[download]

The problem is that, in general, you can't know from a file name which part of it is "extension" and which part is not, unless you either have a clear-cut definition of what "extension" means (I don't know any that satisfies your requirement), or you have a list of all possible extensions.

In reply to Re^3: Splitting an url in its components by moritz
in thread Splitting an url in its components by baurel

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