C:\Users\Peter> perl -e "binmode STDOUT, ':raw'; print qq(\xef\xbb\xbf)" | xxd
00000000: efbb bf                                  ...

C:\Users\Peter> perl -MEncode -e "binmode STDOUT, ':raw'; print Encode::encode('UTF-8', qq(\x{feff}));" | xxd
00000000: efbb bf                                  ...

C:\Users\Peter> perl -e "use open ':std' => ':encoding(UTF-8)'; print qq(\x{feff})" | xxd
00000000: efbb bf                                  ...