The docs say: Generate builder-hex0-x86-stage1.img from hex0 source: sed 's/[;#].*$//g' builder-hex0/builder-hex0-x86-stage1-hex0 | xxd -r -p" That's "builder-hex0/builder-hex0-x86-stage1.hex0", with a dot hex0 at the end, not dash hex0.