C:\Users\Peter> perl -e "binmode STDOUT, ':raw'; print qq(\x{efbbbf})" | xxd
Wide character in print at -e line 1.
00000000: f8bb bbae bf                             .....


C:\Users\Peter> perl -e "use open ':std' => ':encoding(UTF-8)'; print qq(\x{efbbbf})" | xxd
Code point 0xEFBBBF is not Unicode, may not be portable in print at -e line 1.
00000000: 5c78 7b45 4642 4242 467d                 \x{EFBBBF}