[...]
 # Raspbian
 RASPBIAN_URL=http://downloads.raspberrypi.org/raspbian/images/raspbian-2015-02-17/2015-02-16-raspbian-wheezy.zip
 RASPBIAN_SHA1=b71d7b61f44e9bd582df71c9be494c271c97650f
 [...]

 function _get_image {
         echo "Fetching $RASPBIAN_URL "
         mkdir -p download
         RASPBIAN_ARCHIVE_FILE=download/${RASPBIAN_URL##*/}
         wget --no-verbose --continue --directory-prefix download $RASPBIAN_URL || die "Download of $RASPBIAN_URL failed"
         echo -n "Checksum of "
         sha1sum --strict --check - <<<"$RASPBIAN_SHA1 *$RASPBIAN_ARCHIVE_FILE" || die "Download checksum validation failed, please check http://www.raspberrypi.org/downloads"
         unzip -q $RASPBIAN_ARCHIVE_FILE -d temp/ || die "Could not unzip $RASPBIAN_ARCHIVE_FILE"
 }
 [...]

 function _open_image {
         echo "Loop-back mounting" temp/*.img
         kpartx="$(kpartx -av temp/*.img)" || die "Could not setup loop-back access to $RASPBIAN_ARCHIVE_FILE:$NL$kpartx"
         read img_boot_dev img_root_dev <<<$(grep -o 'loop.p.' <<<"$kpartx")
         test "$img_boot_dev" -a "$img_root_dev" || die "Could not extract boot and root loop device from kpartx output:$NL$kpartx"
         img_boot_dev=/dev/mapper/$img_boot_dev
         img_root_dev=/dev/mapper/$img_root_dev
         mkdir -p mnt/img_root
         mount -t ext4 $img_root_dev mnt/img_root || die "Could not mount $img_root_dev mnt/img_root"
         mkdir -p mnt/img_root/boot || die "Could not mkdir mnt/img_root/boot"
         mount -t vfat $img_boot_dev mnt/img_root/boot || die "Could not mount $img_boot_dev mnt/img_root/boot"
         cp -a "$(type -p qemu-arm-static)" mnt/img_root/usr/bin/ || die "Could not copy qemu-arm-static"
         echo "Raspbian Image Details:"
         df -h mnt/img_root/boot mnt/img_root | sed -e "s#$(pwd)/##"
 }
 [...]