or download this
$ perl -wMstrict -CSD -e 'print "\x{FEFF}"' | hexdump -C
00000000 ef bb bf |...|
...
00000000 ff fe 00 00 |....|
$ perl -wMstrict -e 'binmode STDOUT, ":raw:encoding(UTF-32-BE)"; print
+ "\x{FEFF}"' | hexdump -C
00000000 00 00 fe ff |....|