File::Find chdir's to the subdirectory, and you are opening './subdir/file' from the subdirectory. You just need to open '$_', the current filename, since you are in the subdirectory.

And so, BTW, you might want to change this line:

return if $fileName !~ /[\w]+\.(?:cgi|p[lm])$/;
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To this:

return unless /^\w+\.(?:cgi|p[lm])$/;
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