#!/bin/bash
echo "======================================================"
echo "UUID manipulater by Kiyoshi SUZUKI written at 2011/5/8 for Debian Squeeze"
echo "======================================================"
if [ $USER != "root" ];then
 echo "execute me via Root. Abort."
 exit 0
fi
LANG=C
if [ -z "$(apt-cache policy hexedit|grep Installed|grep -v none)" ];then
 echo 'package "hexedit" is not installed. Do you allow installing it ?(yes:y, no:others)'
 read a
 if [ $a = "y" ];then
  apt-get install hexedit||(echo "Installation of hexedit failed. Abort.";exit 0)
 fi 
fi 
starttime=$(date +%Y-%m-%d_%k:%M|tr -d " ")
echo "Starting at $starttime.
This will be added to the copied former configuration files.
===================================================================="
blkid
echo "==============================================="
echo "Type the partition device file name the UUID of which you want to modify (for example, sda1)"
read a
if [ ! -e /dev/$a ];then
 echo "/dev/$a does not exist. Abort!"
 exit 0
fi
filesystem=$(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 $repeatnum - 1)
  done
 fi
}
modify () {
 dd if=/dev/$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 [ $littleendian = "on" ];then littleendian;fi
 check2=$(blkid /dev/$a|tr -d "-"|sed -e "s/.*UUID=\"//" -e "s/\".*//")
 if [ $check1 = $(echo $check2|tr "[A-Z]" "[a-z]") ];then
  olduuid=$(blkid /dev/$a|sed -e "s/.*UUID=\"//" -e "s/\".*//")
  echo "UUID is $olduuid"
  echo "Please type what UUID you want to change to"
  read newuuid
  newuuid=$(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 [ $b = "y" ];then
   check1=$newuuid
   if [ $littleendian = "on" ];then
    littleendian
   fi
   echo "${check1}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 [ $ans = "y" ];then
    dd if=test bs=1 count=$num of=/dev/$a seek=$skip 2>/dev/null && echo "UUID is modified. \"blkid\" command gives:
$(blkid /dev/$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.
I will check /etc/fstab, /boot/grub/grub.cfg, /etc/initramfs-tools/conf.d/resume for $olduuid."
    sync
    newuuid=$(echo $check1|cut -c1-$(echo $cutspace|cut -d " " -f1))
    loc1=$(echo $cutspace|cut -d " " -f1)
    cutspace=$(echo "$cutspace"|cut -d " " -f2-)
    for loc2 in $cutspace;do
     newuuid=$newuuid$(echo -$(echo $check1|cut -c$(expr $loc1 + 1)-$loc2))
     loc1=$loc2
    done
    changefstabetal
   else
    echo "If you want to change, type \"y\". Abort."
    exit 0
   fi
  else
   echo "If you want to change, type \"y\". Abort."
   exit 0
  fi
 else
  echo "Something is wrong. Abort!"
  exit 0
 fi
}
modifyfile () { 
 if [ -e /mnt$file ];then
  if [ $filesystem = "ntfs" -o $filesystem = "vfat" ];then
   olduuid=$(echo $olduuid|tr "[a-z]" "[A-Z]")
   newuuid=$(echo $newuuid|tr "[a-z]" "[A-Z]")
  fi
  if [ "$(grep $olduuid /mnt/$file|grep -v ^#)" ];then
   for line in $(grep -n $olduuid /mnt$file|grep -v ^[0-9]*:#|tr "\t " "_");do
    answer="1"
    while :;do
     echo "There is the following line in $file in $aa:"
     echo $(echo $line|sed -e "s/^[0-9]*/& lines:/")
     echo "Do you change \"$olduuid\" to \"$newuuid\" ?(yes=y,no=n)"
     read answer
     if [ "$answer" = "y" ];then
      perm=$(ls -l /mnt$file|cut -c2-10)
      perm2=$(expr 0 $(echo $perm|cut -c1-3|sed -e "s/r/ + 4/" -e "s/w/ + 2/" -e "s/x/ + 1/" -e "s/-//g"))$(expr 0 $(echo $perm|cut -c4-6|sed -e "s/r/ + 4/" -e "s/w/ + 2/" -e "s/x/ + 1/" -e "s/-//g"))$(expr 0 $(echo $perm|cut -c7-9|sed -e "s/r/ + 4/" -e "s/w/ + 2/" -e "s/x/ + 1/" -e "s/-//g"))
      cp -f /mnt$file /tmp/tempfile${starttime}
      mv -n /mnt$file /mnt${file}${starttime}
      touch /mnt$file
      chmod a+w /mnt$file
      cat /tmp/tempfile${starttime}|sed "$(echo $line|cut -d: -f1)s/$olduuid/$newuuid/" > /mnt$file
      chmod $perm2 /mnt$file
      break
     elif [ "$answer" = "n" ];then break
     fi     
    done
   done
  fi
 fi
}
changefstabetal () {
 deviceslist=$(blkid|cut -d: -f1)
 for aa in $deviceslist;do
  umount -l /mnt 2>/dev/null
  filesystem1=$(blkid $aa|sed -e "s/.*TYPE=\"//"|sed -e "s/\".*//")
  mountpoint1=""
  if [ $filesystem1 = "ntfs" ];then
   if [ "$(mount|grep $aa' ')" ];then
    echo "$aa is mounted now. $aa is tried to be unmounted"
    mountpoint1=$(mount|grep "$aa "|head -n1|tr -s " "|cut -d" " -f3)
    umount -l $aa
   fi
  fi
  mount -t $filesystem1 $aa /mnt -o rw 2>/dev/null || continue
  echo "checking $aa"
  file="/etc/fstab"
  modifyfile
  file="/boot/grub/grub.cfg"
  modifyfile
  file="/boot/grub/menu.lst"
  modifyfile
  file="/etc/initramfs-tools/conf.d/resume"
  modifyfile
  sync
  umount /mnt 2>/dev/null
  sync
  if [ "$mountpoint1" ];then mount -t ntfs $aa $mountpoint1;fi
 done
}
case $filesystem in
 ext2|ext3|ext4)
  olduuid=$(blkid /dev/$a|sed -e "s/.*UUID=\"//" -e "s/\".*//")
  echo "UUID is $olduuid"
  echo "Please type what UUID you want to change to"
  read newuuid
  newuuid=$(echo $newuuid|tr "[A-Z]" "[a-z]"|tr -d -- -)
  newuuid=$(echo "${newuuid}00000000000000000000000000000000"|cut -b1-32)
  if [ $(echo $newuuid|tr -d "0123456789abcdef") ];then
   echo "==============================================="
   echo "UUID must consist of \"0123456789abcdef\" only. Abort."
   echo "==============================================="
   exit 0
  fi
  newuuid="$(echo $newuuid|cut -c1-8)-$(echo $newuuid|cut -c9-12)-$(echo $newuuid|cut -c13-16)-$(echo $newuuid|cut -c17-20)-$(echo $newuuid|cut -c21-32)"
  echo "==============================================="
  echo "Do you want to change UUID of /dev/$a to ${newuuid} ? (Yes:y or No:other)"
  read b
  if [ $b = "y" ];then
   tune2fs -U $newuuid /dev/$a && echo "UUID is modified. \"blkid\" command gives:
$(blkid /dev/$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.
I will check /etc/fstab, /boot/grub/grub.cfg, /etc/initramfs-tools/conf.d/resume."
   sync
   changefstabetal
   exit 0
  else
   echo "If you want to change, type \"y\". Abort."
   exit 0
  fi
 ;;
 swap)
  num=16
  skip=1036
  littleendian="off"
  cutspace="8 12 16 20 32"
  modify
 ;;
 ntfs)
  num=8
  skip=72
  littleendian="on"
  cutspace="16 "
  modify
 ;;
 reiserfs)
  num=16
  skip=65620
  littleendian="off"
  cutspace="8 12 16 20 32"
  modify
 ;;
 btrfs)
  num=16
  skip=65568
  littleendian="off"
  cutspace="8 12 16 20 32"
  modify
 ;;
 vfat)
  littleendian="on"
  cutspace="4 8"
  if [ -n "$(blkid /dev/$a|grep msdos)" ];then
   num=4
   skip=39
  else
   num=4
   skip=67
  fi
  modify
 ;;
 *)
  echo "Filesystem type $filesystem is not supported. Abort."
  exit 0
 ;;
esac
exit 0