#!/bin/bash
echo "==============================================="
echo "UUID manipulater by Kiyoshi SUZUKI at 2011/4/20"
echo "==============================================="
gksu sleep 0
sudo blkid
echo "==============================================="
echo "Type the partition device file name the UUID of which you want to modify (for example, sda1)"
read a
if [ ! -e /dev/$a ];then
 echo "/dev/$a does not exist. Abort!"
 exit 0
fi
filesystem=$(sudo blkid /dev/$a|sed -e "s/.*TYPE=\"//" -e "s/\".*//")
echo "filesystem of /dev/$a is $filesystem"
littleendian () {
 if [ $(expr $(echo $check1|wc -c) % 2) = 0 ];then
  echo "number of word \"$check1\" is odd. Abort."
  exit 0
 else
  repeatnum=$(expr $(expr $(echo $check1|wc -c) - 1) / 2 - 1)
  len=$(expr $(echo $check1|wc -c) - 1)
  while [ 0 -lt $repeatnum ];do
   check1="$(echo $check1|cut -c3-$(expr $(expr $repeatnum \* 2) + 2))$(echo $check1|cut -c1-2)$(if [ $(expr $(expr $repeatnum + 1) \* 2) -lt $len ];then echo $check1|cut -c$(expr $(expr $repeatnum \* 2) + 3)-;fi)"
   repeatnum=$(expr $repeatnum - 1)
  done
 fi
}
modify () {
 sudo dd if=/dev/$a bs=1 count=$num skip=$skip > test 2>/dev/null
 check1=$(hd test |head -n 1| sed -e "s/|.*//"|cut -c 9-|tr -d " ")
 if [ $littleendian = "on" ];then littleendian;fi
 check2=$(sudo blkid /dev/$a|tr -d "-"|sed -e "s/.*UUID=\"//" -e "s/\".*//")
 echo $check1 : $check2 :
 if [ $check1 = $(echo $check2|tr "[A-Z]" "[a-z]") ];then
  echo "UUID is $check2"
  echo "Please type what UUID you want to change to"
  read newuuid
  newuuid=$(echo "${newuuid}00000000000000000000000000000000"|cut -b1-$(expr $num + $num))
  if [ $(echo $newuuid|tr -d "0123456789abcdef") ];then
   echo "==============================================="
   echo "UUID must consist of \"0123456789abcdef\" only. Abort."
   echo "==============================================="
   exit 0
  fi
  echo "==============================================="
  echo "Do you want to change UUID of /dev/$a to ${newuuid} ? (Yes:y or No:other)"
  read b
  if [ $b = "y" ];then
   if [ $littleendian = "on" ];then
    check1=$newuuid
    littleendian
    newuuid=$check1
   fi
   echo "${newuuid}y"|hexedit test 2>/dev/null
   check1=$(hd test|head -n 1| sed -e "s/|.*//"|cut -c 9-|tr -d " ")
   if [ $littleendian = "on" ];then littleendian;fi
   echo "==============================================="
   echo "Please confirm new UUID of /dev/$a is:"
   echo $check1
   echo "Is it OK? (Yes:y, No:other)"
   read ans
   if [ $ans = "y" ];then
    sudo dd if=test bs=1 count=$num of=/dev/$a seek=$skip 2>/dev/null && echo "UUID is modified. \"blkid\" command gives:
$(sudo blkid /dev/$a)
You should manually update (modify) system settings such as /etc/fstab, /boot/grub/grub.cfg, /etc/initramfs-tools/conf.d/resume and so on."
    sudo sync
    exit 0
   else
    echo "If you want to change, type \"y\". Abort."
    exit 0
   fi
  else
   echo "If you want to change, type \"y\". Abort."
   exit 0
  fi
 else
  echo "Something is wrong. Abort!"
  exit 0
 fi
}
case $filesystem in
 ext2|ext3|ext4)
  echo "Please type what UUID you want to change to"
  read newuuid
  newuuid=$(echo $newuuid|tr "[A-Z]" "[a-z]"|tr -d -- -)
  newuuid=$(echo "${newuuid}00000000000000000000000000000000"|cut -b1-32)
  if [ $(echo $newuuid|tr -d "0123456789abcdef") ];then
   echo "==============================================="
   echo "UUID must consist of \"0123456789abcdef\" only. Abort."
   echo "==============================================="
   exit 0
  fi
  echo "==============================================="
  echo "Do you want to change UUID of /dev/$a to ${newuuid} ? (Yes:y or No:other)"
  read b
  if [ $b = "y" ];then
   sudo tune2fs -U "$(echo $newuuid|cut -c1-8)-$(echo $newuuid|cut -c9-12)-$(echo $newuuid|cut -c13-16)-$(echo $newuuid|cut -c17-20)-$(echo $newuuid|cut -c21-32)" /dev/$a && echo "UUID is modified. \"blkid\" command gives:
$(sudo blkid /dev/$a)
You should manually update (modify) system settings such as /etc/fstab, /boot/grub/grub.cfg, /etc/initramfs-tools/conf.d/resume and so on."
   sudo sync
   exit 0
  else
   echo "If you want to change, type \"y\". Abort."
   exit 0
  fi
 ;;
 swap)
  num=16
  skip=1036
  littleendian="off"
  modify
 ;;
 ntfs)
  num=8
  skip=72
  littleendian="on"
  modify
 ;;
 reiserfs)
  num=16
  skip=65620
  littleendian="off"
  modify
 ;;
 btrfs)
  num=16
  skip=65568
  littleendian="off"
  modify
 ;;
 vfat)
  if [ -n "$(sudo blkid /dev/$a|grep msdos)" ];then
   num=4
   skip=39
   littleendian="on"
   modify
  else
   num=4
   skip=67
   littleendian="on"
   modify
  fi
 ;;
 *)
  echo "Filesystem type $filesystem is not supported. Abort."
  exit 0
 ;;
esac
exit 0