diff --git a/script/lib/common.sh b/script/lib/common.sh
new file mode 100644
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--- /dev/null
+++ b/script/lib/common.sh
@@ -0,0 +1,408 @@
+#!/bin/bash -u
+# ******************************************************************************* 
+#                        Confirmation and Passphrase setting 
+# ******************************************************************************* 
+
+function confirmation(){
+
+	# Consistency check for the OVERWRITEINSTALL and ERASEALL
+	if [ "${ERASEALL}" -ne 0 ] && [ "${OVERWRITEINSTALL}" -ne 0 ] ; then 
+		cat <<- HEREDOC 
+		***** ERROR : Confliction between ERASEALL and OVERWRITEINSTALL *****
+		...ERASEALL = ${ERASEALL}
+		...OVERWRITEINSTALL = ${OVERWRITEINSTALL}
+		...Check configuration in your config.sh
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+	fi
+
+	# Sanity check for volume group name
+	if echo "${VGNAME}" | grep "-" -i > /dev/null ; then	# "-" is found in the volume group name.
+		cat <<- HEREDOC 
+		***** ERROR : VGNAME is "${VGNAME}" *****
+		..."-" is not allowed in the volume name. 
+		...Check configuration in your config.sh
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+	fi # "-" is found in the volume group name.
+
+	# Sanity check for root volume name
+	if echo "${LVROOTNAME}" | grep "-" -i > /dev/null ; then	# "-" is found in the volume name.
+		cat <<- HEREDOC 
+		***** ERROR : LVROOTNAME is "${LVROOTNAME}" *****
+		..."-" is not allowed in the volume name. 
+		...Check configuration in your config.sh
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+	fi # "-" is found in the volume name.
+
+	# Sanity check for swap volume name
+	if echo "${LVSWAPNAME}" | grep "-" -i > /dev/null ; then	# "-" is found in the volume name.
+		cat <<- HEREDOC 
+		***** ERROR : LVSWAPNAME is "${LVSWAPNAME}" *****
+		..."-" is not allowed in the volume name. 
+		...Check configuration in your config.sh
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+	fi # "-" is found in the volume name.
+
+	# For surre ask the your config.sh is edited
+	cat <<- HEREDOC
+
+	The destination logical volume label is "${LVROOTNAME}"
+	"${LVROOTNAME}" uses ${LVROOTSIZE} of the LVM volume group.
+	Are you sure to install? [Y/N]
+	HEREDOC
+	read -r YESNO
+	if [ "${YESNO}" != "Y" ] && [ "${YESNO}" != "y" ] ; then
+		cat <<- HEREDOC 
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+	fi	# if YES
+
+	# For sure ask to erase. 
+	if [ "${ERASEALL}" -ne 0 ] ; then
+		echo "Are you sure you want to erase entire \"${DEV}\"? [Y/N]"
+		read -r YESNO
+		if [ "${YESNO}" != "Y" ] && [ "${YESNO}" != "y" ] ; then
+			cat <<-HEREDOC 
+		...Check your config.sh. The variable ERASEALL is ${ERASEALL}.
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+		fi	# if YES
+	fi	# if erase all
+
+	# For sure ask to overwrite. 
+	if [ "${OVERWRITEINSTALL}" -ne 0 ] ; then
+		echo "Are you sure you want to overwrite \"${LVROOTNAME}\" in \"${VGNAME}\"? [Y/N]"
+		read -r YESNO
+		if [ "${YESNO}" != "Y" ] && [ "${YESNO}" != "y" ] ; then
+			cat <<-HEREDOC 
+		...Check your config.sh. The variable OVERWRITEINSTALL is ${OVERWRITEINSTALL}.
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+		fi	# if YES
+	fi	# if overwrite
+
+	# ----- Set Passphrase -----
+	# Input passphrase
+	echo ""
+	echo "Type passphrase for the disk encryption."
+	read -sr PASSPHRASE
+	export PASSPHRASE
+
+	echo "Type passphrase again, to confirm."
+	read -sr PASSPHRASE_C
+
+	# Validate whether both are indentical or not
+	if [ "${PASSPHRASE}" != "${PASSPHRASE_C}" ] ; then
+		cat <<-HEREDOC 
+		***** ERROR : Passphrase doesn't match *****
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+	fi	# passphrase validation
+
+	# succesfull return
+	return 0
+}
+
+
+# ******************************************************************************* 
+#                           Common Pre-install stage 
+# ******************************************************************************* 
+
+function pre_install() {
+
+
+	# ----- Erase entire disk, create partitions, format them  and encrypt the LUKS partition -----
+	if [ "${ERASEALL}" -ne 0 ] ; then
+
+		# Assign specified space and rest of disk to the EFI and LUKS partition, respectively.
+		if [  "${ISEFI}" -ne 0 ] ; then # EFI
+			# Zap existing partition table and create new GPT
+			echo "...Initializing \"${DEV}\" with GPT."
+			sgdisk --zap-all "${DEV}"
+			if is_error ; then return 1 ; fi; 	# If error, terminate
+			# Create EFI partition and format it
+			echo "...Creating an EFI partition on \"${DEV}\"."
+			# shellcheck disable=SC2140
+			sgdisk --new="${EFIPARTITION}":0:+"${EFISIZE}" --change-name="${EFIPARTITION}":"EFI System"  --typecode="${EFIPARTITION}":ef00 "${DEV}"  
+			if is_error ; then return 1 ; fi; 	# If error, terminate
+			echo "...Formatting the EFI parttion."
+			mkfs.vfat -F 32 -n EFI-SP "${DEV}${EFIPARTITION}"
+			if is_error ; then return 1 ; fi; 	# If error, terminate
+			# Create Linux partition
+			echo "...Creating a Linux partition on ${DEV}."
+			# shellcheck disable=SC2140
+			sgdisk --new="${CRYPTPARTITION}":0:0    --change-name="${CRYPTPARTITION}":"Linux LUKS" --typecode="${CRYPTPARTITION}":8309 "${DEV}"
+			if is_error ; then return 1 ; fi; 	# If error, terminate
+			# Then print them
+			sgdisk --print "${DEV}"
+		else # BIOS
+			# Zap existing partition table
+			echo "...Erasing partition table of \"${DEV}\"."
+			dd if=/dev/zero of="${DEV}" bs=512 count=1
+			if is_error ; then return 1 ; fi; 	# If error, terminate
+			# Create MBR and allocate max storage for Linux partition
+			echo "...Creating a Linux partition on ${DEV} with MBR."
+			sfdisk "${DEV}" <<- HEREDOC
+			2M,,L
+			HEREDOC
+			if is_error ; then return 1 ; fi; 	# If error, terminate
+		fi	# if EFI firmware
+
+		# Encrypt the partition to install Linux
+		echo "...Initializing \"${DEV}${CRYPTPARTITION}\" as crypt partition"
+		printf %s "${PASSPHRASE}" | cryptsetup luksFormat --type=luks1 --key-file - --batch-mode "${DEV}${CRYPTPARTITION}"
+
+	fi	# if erase all
+
+	# ----- Open the LUKS partition -----
+	# Open the crypt partition. 
+	echo "...Opening a crypt partition \"${DEV}${CRYPTPARTITION}\" as \"${CRYPTPARTNAME}\""
+	printf %s "${PASSPHRASE}" | cryptsetup open -d - "${DEV}${CRYPTPARTITION}" "${CRYPTPARTNAME}"
+
+	# Check whether successful open. If mapped, it is successful. 
+	if [ ! -e /dev/mapper/"${CRYPTPARTNAME}" ] ; then 
+		cat <<- HEREDOC 
+		***** ERROR : Cannot open LUKS volume "${CRYPTPARTNAME}" on "${DEV}${CRYPTPARTITION}". *****
+		...Check passphrase and your config.txt
+
+		...Installation process terminated..
+		HEREDOC
+		return 1 # with error status
+	fi	# if crypt volume is unable to open
+
+	# ----- Configure the LVM in LUKS volume -----
+	# Check volume group ${VGNAME} exist or not
+	if  vgdisplay -s "${VGNAME}" &> /dev/null ; then		# if exist
+		echo "...Volume group \"${VGNAME}\" already exist. Skipped to create. No problem."
+		echo "...Activating all logical volumes in volume group \"${VGNAME}\"."
+		vgchange -ay
+		echo "...Scanning all logical volumes."
+		lvscan
+	else
+		echo "...Initializing a physical volume on \"${CRYPTPARTNAME}\""
+		pvcreate /dev/mapper/"${CRYPTPARTNAME}"
+		if [ $? -ne 0 ] ; then deactivate_and_close; return 1 ; fi;
+		echo "...And then creating Volume group \"${VGNAME}\"."
+		vgcreate "${VGNAME}" /dev/mapper/"${CRYPTPARTNAME}"
+		if [ $? -ne 0 ] ; then deactivate_and_close; return 1 ; fi;
+	fi # if /dev/volume-groupt exist
+
+	# Create a SWAP Logical Volume on VG, if it doesn't exist
+	if [ -e /dev/mapper/"${VGNAME}"-"${LVSWAPNAME}" ] ; then 
+		echo "...Swap volume already exist. Skipped to create. No problem."
+	else
+		echo "...Creating logical volume \"${LVSWAPNAME}\" on \"${VGNAME}\"."
+		lvcreate -L "${LVSWAPSIZE}" -n "${LVSWAPNAME}" "${VGNAME}" 
+		if [ $? -ne 0 ] ; then deactivate_and_close; return 1 ; fi;
+	fi	# if /dev/mapper/swap volume already exit. 
+
+	# Create a ROOT Logical Volume on VG. 
+	if [ -e /dev/mapper/"${VGNAME}"-"${LVROOTNAME}" ] ; then # exist
+		if [ "${OVERWRITEINSTALL}" -ne 0 ] ; then # exist and overwrite install
+			echo "...Logical volume \"${VGNAME}-${LVROOTNAME}\" already exists. OK."
+		else	# exist and not overwriteinstall
+			cat <<- HEREDOC 
+			***** ERROR : Logical volume "${VGNAME}-${LVROOTNAME}" already exists. *****
+			...Check LVROOTNAME environment variable in your config.txt.
+			HEREDOC
+			# Deactivate all lg and close the LUKS volume
+			deactivate_and_close
+			return 1 # with error status
+		fi
+	else	# not exsit
+		if [ "${OVERWRITEINSTALL}" -ne 0 ] ; then
+			cat <<- HEREDOC 
+			***** ERROR : Logical volume "${VGNAME}-${LVROOTNAME}" doesn't exist while overwrite install. *****
+			...Check consistency of your config.txt.
+			HEREDOC
+			# Deactivate all lg and close the LUKS volume
+			deactivate_and_close
+			return 1 # with error status
+		else # not exist and not overwrite install
+			echo "...Creating logical volume \"${LVROOTNAME}\" on \"${VGNAME}\"."
+			lvcreate -l "${LVROOTSIZE}" -n "${LVROOTNAME}" "${VGNAME}"
+			if [ $? -ne 0 ] ; then deactivate_and_close; return 1 ; fi;
+		fi
+	fi
+
+
+	# successful return
+	return 0
+}
+
+
+# ******************************************************************************* 
+#                  Common message in para-install stage
+# ******************************************************************************* 
+
+function para_install_msg() {
+
+	cat <<- HEREDOC
+	******************************************************************************
+	The pre-install process is done. We are ready to install the Linux to the 
+	target storage device. By pressing return key, GUI/TUI installer starts.
+
+	Please pay attention to the partition/logical volume mapping configuration. 
+	In this installation, you have to map the previously created partitions/logical
+	volumes to the appropriate directories of the target system as followings :
+
+	HEREDOC
+
+	# In the EFI system, add this mapping
+	if [  "${ISEFI}" -ne 0 ] ; then
+		echo "/boot/efi        : ${DEV}${EFIPARTITION}"
+	fi
+
+	# Root volume mapping
+	echo "/                : /dev/mapper/${VGNAME}-${LVROOTNAME}"
+
+	# In case of erased storage, add this mapping
+	if [ "${ERASEALL}" -ne 0 ] ; then
+		echo "swap             : /dev/mapper/${VGNAME}-${LVSWAPNAME}"
+	fi
+
+	return 0
+}
+
+
+# ******************************************************************************* 
+#                  Common post-install stage
+# ******************************************************************************* 
+# In side this script, the chrooted job is parameterrized as by evn variable TARGETCHROOTEDJOB
+function post_install_local() {
+	## Mount the target file system
+	# ${TARGETMOUNTPOINT} is created by the GUI/TUI installer
+	echo "...Mounting /dev/mapper/${VGNAME}-${LVROOTNAME} on ${TARGETMOUNTPOINT}."
+	mount /dev/mapper/"${VGNAME}"-"${LVROOTNAME}" "${TARGETMOUNTPOINT}"
+
+	# And mount other directories
+	echo "...Mounting all other dirs."
+	for n in proc sys dev tmp etc/resolv.conf; do mount --rbind "/$n" "${TARGETMOUNTPOINT}/$n"; done
+
+	# Copy all scripts to the target /tmp
+	echo "...Copy files in current dir to ${TARGETMOUNTPOINT}/tmp."
+	mkdir "${TARGETMOUNTPOINT}/tmp/kaiten-yaki"
+	cp -R ./*.sh "${TARGETMOUNTPOINT}/tmp/kaiten-yaki"
+
+	# Change root and create the keyfile and ramfs image for Linux kernel. 
+	# The here document is script executed under chroot. And here we call 
+	# the distribution dependent script "lib/chrooted_job_${DISTRIBUTIONSIGNATURE}.sh".
+	echo "...Chroot to ${TARGETMOUNTPOINT}."
+	# shellcheck disable=SC2086
+	cat <<- HEREDOC | chroot "${TARGETMOUNTPOINT}" /bin/bash
+		cd /tmp/kaiten-yaki
+		# Execute copied script
+		source "lib/chrooted_job_${DISTRIBUTIONSIGNATURE}.sh"
+	HEREDOC
+
+	# Unmount all
+	echo "...Unmounting all."
+	umount -R "${TARGETMOUNTPOINT}"
+
+	# Finishing message
+	cat <<- HEREDOC
+	****************** Post-install process finished ******************
+
+	...Ready to reboot.
+	HEREDOC
+
+	return 0
+	
+} # End of post_install_local()
+
+
+# ******************************************************************************* 
+#              Deactivate all LV in the VG and close LUKS volume
+# ******************************************************************************* 
+
+function deactivate_and_close(){
+	echo "...Deactivating all logical volumes in volume group \"${VGNAME}\"."
+	vgchange -a n "${VGNAME}"
+	echo "...Closing LUKS volume \"${CRYPTPARTNAME}\"."
+	cryptsetup close  "${CRYPTPARTNAME}"
+	cat <<- HEREDOC 
+
+	...Installation process terminated..
+	HEREDOC
+
+}
+
+# ******************************************************************************* 
+#              Delete the nwe volume if overwrite install, and close all
+# ******************************************************************************* 
+function on_unexpected_installer_quit(){
+	echo "***** ERROR : The GUI/TUI installer terminated unexpectedly. *****" 
+	if [ "${OVERWRITEINSTALL}" -ne 0 ] ; then	# If overwrite install, keep the volume
+		echo "...Keep logical volume \"${VGNAME}-${LVROOTNAME}\" untouched."
+	else # if not overwrite istall, delete the new volume
+		echo "...Deleting the new logical volume \"${VGNAME}-${LVROOTNAME}\"."
+		lvremove -f /dev/mapper/"${VGNAME}"-"${LVROOTNAME}" 
+	fi
+	# Deactivate all lg and close the LUKS volume
+	deactivate_and_close
+	echo "...You can retry Kaiten-yaki again." 
+}
+
+
+# ******************************************************************************* 
+#              Check whether given signaure is in the system information
+# ******************************************************************************* 
+function distribution_check(){
+	if ! uname -a | grep "${DISTRIBUTIONSIGNATURE}" -i > /dev/null  ; then	#  Signature is not found in the OS name.
+		echo "*******************************************************************************"
+		uname -a
+		cat <<- HEREDOC 
+		*******************************************************************************
+		This system seems to be not $DISTRIBUTIONNAME, while this script is dediated to the $DISTRIBUTIONNAME.
+		Are you sure you want to run this script? [Y/N]
+		HEREDOC
+		read -r YESNO
+		if [ "${YESNO}" != "Y" ] && [ "${YESNO}" != "y" ] ; then
+			cat <<- HEREDOC 
+
+			...Installation process terminated..
+			HEREDOC
+			return 1 # with error status
+		fi	# if YES
+
+	fi # Distribution check
+
+	# no error
+	return 0
+}
+
+
+# ******************************************************************************* 
+#              Error report and return revsers status.  
+# ******************************************************************************* 
+function is_error() {
+	if [ $? -eq 0 ] ; then # Is previous job OK? 
+		return 1	# If OK, return error ( because it was not error )
+	else
+		cat <<- HEREDOC
+		**** ERROR ! ****
+
+		Installation process terminated. 
+		HEREDOC
+		return 0	# If error, return OK ( because it was error )
+	fi;
+}
\ No newline at end of file