$ printf 'A\nB\na\n' | LC_ALL=en_US.UTF-8 sort -i A B a $ rpm -qf $(type -p sort) coreutils-8.21-20.fc21.x86_64 This probably because of broken multi-byte patch (bug #1003544) because coreutils-8.21-16.fc20.x86_64 sorts as expected: $ printf 'A\nB\na\n' | LC_ALL=en_US.UTF-8 sort -i a A B
Does occur even with the C locales... btw. -i doesn't mean case insensitive sort - it does mean "ignore nonprinting characters". I think you want -f option, which seems to work properly. With coreutils-8.21-20 (compiled on RHEL-6) printf 'A\nB\na\nb\n' | LC_ALL=C ./sort -i A B a b printf 'A\nB\na\n' | LC_ALL=C ./sort -f A a B printf 'A\nB\na\n' | LC_ALL=en_US.UTF-8 ./sort -f A a B For me, it looks more like something was fixed than broken. Can you confirm?
God damn! I lived in a lie until now. The `-f' option works for me. I tested it in en_US.UTF-8, cs_CZ.UTF-8 and C locales.