curl -sSL http://git.io/vvDYD > mkarch; chmod +x mkarch; disk=/dev/sdb ./mkarch

mkarch.sh

#!/bin/bash
set -e
set -x

disk="/dev/sdb"
rootfs="ArchLinuxARM-rpi-2-latest.tar.gz"

pushd $(mktemp -d)
  mkdir root boot

  mkfs.vfat ${disk}1
  mkfs.ext4 ${disk}2

  mount ${disk}1 boot
  mount ${disk}2 root

  if [ ! -f ~/${rootfs} ]; then
    curl -fsSL http://archlinuxarm.org/os/${rootfs} > ~/${rootfs}
  fi

  ln -nfs ~/${rootfs} ${rootfs}

  bsdtar -xpf ${rootfs} -C root
  mv root/boot/* boot
  sync
  
  umount root boot
  rm -rf root boot
popd