If you're in linux you can just type that into a shell and it will work. What it does (and you can emulate in other OSs) is concatenate the bytes of the jpeg fi

If you're in linux you can just type that into a shell and it will work. What it does (and you can emulate in other OSs) is concatenate the bytes of the jpeg file with the bytes of the zip file and save them as one huge blob, which will be readable as either of those.