James Youngman wrote:
Findutils uses the regular expression implementation from gnulib. So this problem likely also exists there, or perhaps has already been fixed there.
I can't seem to reproduce the problem on Fedora 24, so perhaps it's been fixed already.
$ ls
a.lower b.UPPER
$ LC_COLLATE=pl_PL.utf8 find -regextype gnu-awk -regex '.*[a-z]{5}$'
./a.lower
$ LC_COLLATE=pl_PL.utf8 find -regextype gnu-awk -regex '.*[A-Z]{5}$'
./b.UPPER
$ find --version | head -n1
find (GNU findutils) 4.6.0
