change_partition_uuid.sh

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

# Do not try to change the UUID's of partitions of eMMC or SD-cards plugged into their native odroid slot. 
# If you want to use an odroid for this, connect the memory via USB-adapter (e.g. device /dev/sda ).


if [ $# -eq 0 ] ; then
  echo "usage: $0 <device>"
  exit 1
fi


export OTHER_DEVICE="$1"

if [ ! $(lsblk -o KNAME,TYPE ${OTHER_DEVICE} | grep -c "disk\|loop") -eq 1 ] ; then
  echo "device $1 not found."
  exit 1
fi

export OTHER_DEVICE=`basename ${OTHER_DEVICE}`

echo "OTHER_DEVICE: /dev/${OTHER_DEVICE}"



function dev_suffix {

  if [[ $1 =~ ^"/dev/sd" ]] ; then
    echo ""
    return 0
  fi
  if [[ $1 =~ ^"/dev/mmcblk" ]] ; then
    echo "p"
    return 0
  fi
  if [[ $1 =~ ^"/dev/disk" ]] ; then
	echo "s"
	return 0
  fi
  if [[ $1 =~ ^"/dev/loop" ]] ; then
	echo "p"
	return 0
  fi

  echo "unknown"
  return 1
}

export OTHER_DEV_SUFFIX=`dev_suffix "/dev/${OTHER_DEVICE}"`
if [ "${OTHER_DEV_SUFFIX}_" == "unknown_" ] ; then
  exit 1
fi

echo "OTHER_DEV_SUFFIX: ${OTHER_DEV_SUFFIX}"



if ! $(hash uuidgen 2>/dev/null) ; then
  apt-get update
  apt-get install -y uuid-runtime
fi

export LC_CTYPE=C 

# "tail -n +1" is a trick to prevent broken pipe
export NEWUUID_1=`cat /dev/urandom | tr -dc 'A-F0-9' | tail -n +1 | head -c 4` ; echo "NEWUUID_1: ${NEWUUID_1}"
export NEWUUID_2=`uuidgen` ; echo "NEWUUID_2: ${NEWUUID_2}"

# turn ASCII into HEX representation, eg: "5A51-334D"
export NEWUUID_1_HEX=`echo -n "${NEWUUID_1}" | od -t x2 | head -n 1 | sed "s/^0000000 \([^ ]*\) \([^ ]*\)/\2-\1/" | tr '[a-z]' '[A-Z]' | tr -d '\n'` ; echo "NEWUUID_1_HEX: ${NEWUUID_1_HEX}"


# umount does not work reliable as it it is confused by th euuid !!!!

#unmount the other partitions
#set +e
#if [ $(df -h | grep -c /dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}1 ) == 1 ] ; then
#  while ! $(umount /dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}1) ; do sleep 3 ; done
#fi
#if [ $(df -h | grep -c /dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}2 ) == 1 ] ; then
#  while ! $(umount /dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}2) ; do sleep 3 ; done
#fi
#set -e
#sleep 2

###  change UUID on other devices
tune2fs -U ${NEWUUID_2} /dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}2

# the boot partition uses FAT16. To change the UUID we use dd
echo -n "${NEWUUID_1}" | dd of=/dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}1 bs=1 seek=39 count=4
# FAT16: (seek=39 count=4)
# FAT32: (seek=67 count=4)
# NTFS: (seek=72 count=8)


# fstab on other device
mkdir -p /media/other/
mount /dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}2 /media/other/
sed -i.bak -e "s/[^ ]*[ $'\t']*\/[ $'\t']/UUID=${NEWUUID_2}\t\/\t/" \
           -e "s/[^ ]*[ $'\t']*\/media\/boot[ $'\t']/UUID=${NEWUUID_1_HEX}\t\/media\/boot\t/" /media/other/etc/fstab
# verify: diff /media/other/etc/fstab /media/other/etc/fstab.bak
set +e
while ! $(umount /media/other/) ; do sleep 3 ; done
set -e

#boot.scr on the boot partition of the other device
mkdir -p /media/other_boot/
mount /dev/${OTHER_DEVICE}${OTHER_DEV_SUFFIX}1 /media/other_boot/
for file in boot.txt boot.ini ; do
  if [ -e /media/other_boot/${file} ] ; then
    sed -i.bak -e "s/root\=[^ ]*/root=UUID=${NEWUUID_2}/" /media/other_boot/${file}
  fi
done
#verify: diff ./boot.ini ./boot.ini.bak
# TODO: mkimage may not be needed 
#mkimage -A arm -T script -C none -n boot -d /media/other_boot/boot.ini /media/other_boot/boot.scr
set +e
while ! $(umount /media/other_boot/) ; do sleep 3 ; done


#maybe needed
#fix boot partition
#dosfsck -t -a -w  /dev/mmcblk1p1