diff --git a/.github/workflows/build-action.yml b/.github/workflows/build-action.yml
index 3c56f53f8..4f87b54b1 100644
--- a/.github/workflows/build-action.yml
+++ b/.github/workflows/build-action.yml
@@ -1,4 +1,4 @@
-name: Build Image
+name: Build openHABian images
 
 # Trigger the workflow on push or pull request
 on:
@@ -6,10 +6,12 @@ on:
     paths:
       - 'build.bash'
       - 'build-image/openhabian-installer.service'
+      - 'includes/offline-image-modifications.bash'
   pull_request:
     paths:
       - 'build.bash'
       - 'build-image/openhabian-installer.service'
+      - 'includes/offline-image-modifications.bash'
   workflow_dispatch:
     inputs:
       comments:
@@ -27,31 +29,29 @@ jobs:
          with:
            repository: ${{ github.event.pull_request.head.repo.full_name }}
            ref: ${{ github.event.pull_request.head.ref }}
-       - name: Environment variables
-         run: sudo -E bash -c set
-       - name: Install required packages
-         run: sudo apt-get install git curl unzip libarchive-zip-perl dos2unix xz-utils kpartx
-       - name: getimagename
-         id: getimagename
+       - name: Setup environment
+         id: setup
          run: |
+           sudo -E bash -c set
+           sudo apt-get update
+           sudo apt-get install --yes libarchive-zip-perl dos2unix systemd-container qemu-user-static qemu-utils
            echo "::set-output name=image::$(basename "$(curl "https://downloads.raspberrypi.org/raspios_lite_armhf_latest" -s -L -I  -o /dev/null -w '%{url_effective}')")"
        - name: Cache Raspberry Pi OS image
          uses: actions/cache@v2
          with:
-           path: ${{ steps.getimagename.outputs.image }}
-           key: ${{ steps.getimagename.outputs.image }}
-       - name: Run build.bash rpi
+           path: ${{ steps.setup.outputs.image }}
+           key: ${{ steps.setup.outputs.image }}
+       - name: Build openHABian 32bit image
+         id: build
          run: |
            sudo -E ./ci-setup.bash github pi-raspios32
            sudo -E ./build.bash rpi
-       - name: getfilename
-         id: getfilename
-         run: echo "::set-output name=file::$(ls openhabian-*.img.xz)"
-       - name: Archive
+           echo "::set-output name=file::$(ls openhabian-*.img.xz)"
+       - name: Archive openHABian 32bit image
          uses: actions/upload-artifact@v2
          with:
-           name: ${{ steps.getfilename.outputs.file }}
-           path: ${{ steps.getfilename.outputs.file }}
+           name: ${{ steps.build.outputs.file }}
+           path: ${{ steps.build.outputs.file }}
   build64experimental:
     # Using latest Ubuntu (not the GitHub Actions default) to get latest tool versions in GitHub Actions environment
     runs-on: ubuntu-20.04
@@ -62,28 +62,26 @@ jobs:
          with:
            repository: ${{ github.event.pull_request.head.repo.full_name }}
            ref: ${{ github.event.pull_request.head.ref }}
-       - name: Environment variables
-         run: sudo -E bash -c set
-       - name: Install required packages
-         run: sudo apt-get install git curl unzip libarchive-zip-perl dos2unix xz-utils kpartx
-       - name: getimagename
-         id: getimagename
+       - name: Setup environment
+         id: setup
          run: |
+           sudo -E bash -c set
+           sudo apt-get update
+           sudo apt-get install --yes libarchive-zip-perl dos2unix systemd-container qemu-user-static qemu-utils
            echo "::set-output name=image::$(basename "$(curl "https://downloads.raspberrypi.org/raspios_lite_arm64_latest" -s -L -I  -o /dev/null -w '%{url_effective}')")"
        - name: Cache Raspberry Pi OS image
          uses: actions/cache@v2
          with:
-           path: ${{ steps.getimagename.outputs.image }}
-           key: ${{ steps.getimagename.outputs.image }}
-       - name: Run build.bash rpi64
+           path: ${{ steps.setup.outputs.image }}
+           key: ${{ steps.setup.outputs.image }}
+       - name: Build openHABian 64bit image
+         id: build
          run: |
            sudo -E ./ci-setup.bash github pi-raspios64beta
            sudo -E ./build.bash rpi64
-       - name: getfilename
-         id: getfilename
-         run: echo "::set-output name=file::$(ls openhabian-*.img.xz)"
-       - name: Archive
+           echo "::set-output name=file::$(ls openhabian-*.img.xz)"
+       - name: Archive openHABian 64bit image
          uses: actions/upload-artifact@v2
          with:
-           name: ${{ steps.getfilename.outputs.file }}
-           path: ${{ steps.getfilename.outputs.file }}
+           name: ${{ steps.build.outputs.file }}
+           path: ${{ steps.build.outputs.file }}
diff --git a/.github/workflows/shellcheck-action.yml b/.github/workflows/shellcheck-action.yml
index 31d15c9f4..a63eb70e5 100644
--- a/.github/workflows/shellcheck-action.yml
+++ b/.github/workflows/shellcheck-action.yml
@@ -21,10 +21,8 @@ jobs:
     steps:
        - name: Checkout repository
          uses: actions/checkout@v2
-       - name: Environment variables
+       - name: Setup environment
          run: sudo -E bash -c set
-       - name: Install required packages
-         run: sudo apt-get install shellcheck
        - name: "ShellCheck openhabian-setup.sh"
          run: |
            echo "ShellCheck openhabian-setup.sh..."
diff --git a/build-image/first-boot.bash b/build-image/first-boot.bash
index 40da3e853..de1144708 100755
--- a/build-image/first-boot.bash
+++ b/build-image/first-boot.bash
@@ -173,9 +173,9 @@ fi
 
 if [[ -x $(command -v python3) ]]; then bash /boot/webserver.bash "reinsure_running"; fi
 
-if ! dpkg -s 'git' &> /dev/null; then
+if ! [[ -x $(command -v git) ]]; then
   echo -n "$(timestamp) [openHABian] Installing git package... "
-  if apt-get install --yes git &> /dev/null; then echo "OK"; else echo "FAILED"; fi
+  if apt-get install --yes git; then echo "OK"; else echo "FAILED"; fi
 fi
 
 # shellcheck disable=SC2154
@@ -184,6 +184,7 @@ type openhabian_update &> /dev/null && if ! openhabian_update &> /dev/null; then
   echo "FAILED"
   echo "$(timestamp) [openHABian] The git repository on the public internet is not reachable."
   echo "$(timestamp) [openHABian] We will continue trying to get your system installed, but this is not guaranteed to work."
+  export OFFLINE="1"
 else
   echo "OK"
 fi
diff --git a/build-image/openhabian.conf b/build-image/openhabian.conf
index 1e4dc1ed4..00bf10e3a 100644
--- a/build-image/openhabian.conf
+++ b/build-image/openhabian.conf
@@ -77,5 +77,5 @@ java_opt=Zulu8-64
 #relaypass=secret
 #smarthost=smtp.gmail.com
 #smartport=587
-#
+
 # vim: filetype=sh
diff --git a/build-image/openhabian.pi-raspios64beta.conf b/build-image/openhabian.pi-raspios64beta.conf
index cb28a9d2d..7de73099a 100644
--- a/build-image/openhabian.pi-raspios64beta.conf
+++ b/build-image/openhabian.pi-raspios64beta.conf
@@ -78,5 +78,5 @@ java_opt=Zulu11-64
 #relaypass=secret
 #smarthost=smtp.gmail.com
 #smartport=587
-#
+
 # vim: filetype=sh
diff --git a/build.bash b/build.bash
index f410f7581..5a6de6393 100755
--- a/build.bash
+++ b/build.bash
@@ -11,14 +11,14 @@ usage() {
 }
 
 cleanup_build() {
-  if [[ -z "$buildfolder" ]]; then exit 1; fi
+  if [[ -z "$buildFolder" ]]; then exit 1; fi
 
-  umount "$buildfolder/boot" &> /dev/null || true
-  umount "$buildfolder/root" &> /dev/null || true
-  guestunmount --no-retry "$buildfolder/boot" &> /dev/null || true
-  guestunmount --no-retry "$buildfolder/root" &> /dev/null || true
+  umount "${buildFolder}/boot" &> /dev/null || true
+  umount "${buildFolder}/root" &> /dev/null || true
+  guestunmount --no-retry "${buildFolder}/boot" &> /dev/null || true
+  guestunmount --no-retry "${buildFolder}/root" &> /dev/null || true
 
-  rm -rf "$buildfolder"
+  rm -rf "$buildFolder"
 }
 
 ##########################
@@ -26,6 +26,12 @@ cleanup_build() {
 ##########################
 # shellcheck source=functions/helpers.bash
 source "$(dirname "$0")"/functions/helpers.bash
+# shellcheck source=functions/java-jre.bash
+source "$(dirname "$0")"/functions/java-jre.bash
+# shellcheck source=functions/zram.bash
+source "$(dirname "$0")"/functions/zram.bash
+# shellcheck source=functions/packages.bash
+source "$(dirname "$0")"/functions/packages.bash
 
 ## This function formats log messages
 ##
@@ -37,45 +43,45 @@ echo_process() {
 
 ## Function for identify and returning current active git repository and branch
 ##
-## Returns global variable $clone_string
+## Returns global variable $cloneString
 ##
 ##    get_git_repo()
 ##
 get_git_repo() {
-  local repo_url repo_branch user_name repo_name
+  local repoURL repoBranch userName repoName
 
-  repo_url="$(git remote get-url origin)"
-  repo_branch="$(git rev-parse --abbrev-ref HEAD)"
+  repoURL="$(git remote get-url origin)"
+  repoBranch="$(git rev-parse --abbrev-ref HEAD)"
 
-  if ! [[ $repo_url == "https"* ]]; then
+  if ! [[ $repoURL == "https"* ]]; then
     # Convert URL from SSH to HTTPS
-    user_name="$(echo "$repo_url" | sed -Ene's#git@github.com:([^/]*)/(.*).git#\1#p')"
-    if [[ -z $user_name ]]; then
+    userName="$(echo "$repoURL" | sed -Ene's#git@github.com:([^/]*)/(.*).git#\1#p')"
+    if [[ -z $userName ]]; then
       echo_process "Could not identify git user while converting to SSH URL. Exiting."
       exit 1
     fi
-    repo_name="$(echo "$repo_url" | sed -Ene's#git@github.com:([^/]*)/(.*).git#\2#p')"
-    if [[ -z $repo_name ]]; then
+    repoName="$(echo "$repoURL" | sed -Ene's#git@github.com:([^/]*)/(.*).git#\2#p')"
+    if [[ -z $repoName ]]; then
       echo_process "Could not identify git repo while converting to SSH URL. Exiting."
       exit 1
     fi
-    repo_url="https://github.com/${user_name}/${repo_name}.git"
+    repoURL="https://github.com/${userName}/${repoName}.git"
   fi
 
-  clone_string="${repo_branch} ${repo_url}"
+  cloneString="${repoBranch} ${repoURL}"
 }
 
 ## Function for injecting custom development branch when building images.
 ## This function will also watermark the image as a test build.
 ##
 ## The first parameter shall be the temporary first-boot.bash file used when building the image.
-## The global varible $clone_string must be set prior running this function.
+## The global varible $cloneString must be set prior running this function.
 ##
 ##    inject_build_repo(String path)
 ##
 inject_build_repo() {
-  if [[ -z "${clone_string+x}" ]]; then
-    echo_process "inject_build_repo() invoked without clone_string variable set, exiting...."
+  if [[ -z "${cloneString+x}" ]]; then
+    echo_process "inject_build_repo() invoked without cloneString variable set, exiting...."
     exit 1
   fi
   sed -i '$a /usr/bin/apt-get install --yes figlet &>/dev/null' "$1"
@@ -109,78 +115,115 @@ check_command_availability_and_exit() {
   done
 }
 
-# mount rpi image using userspace tools, in docker use privileged mount via kpartx
-mount_image_file_boot() { # imagefile buildfolder
+## Mount RPi Image with userspace tools, for docker we use kpartx
+##
+##    mount_image_file_boot(String imageFile, String buildFolder)
+##
+mount_image_file_boot() {
+  local imageFile="$1"
+  local buildFolder="$2"
+  local loopPrefix
+
   if ! running_in_docker && ! running_on_github && ! is_pi; then
-    guestmount --format=raw -o uid=$EUID -a "$1" -m /dev/sda1 "$2/boot"
+    guestmount --format=raw -o uid="$EUID" -a "$imageFile" -m /dev/sda1 "${2}/boot"
   else
-    loop_prefix=$(kpartx -asv "$1" | grep -oE "loop([0-9]+)" | head -n 1)
-    mount -o rw -t vfat "/dev/mapper/${loop_prefix}p1" "$buildfolder/boot"
+    loopPrefix="$(kpartx -asv "$imageFile" | grep -oE "loop([0-9]+)" | head -n 1)"
+    mount -o rw -t vfat "/dev/mapper/${loopPrefix}p1" "${buildFolder}/boot"
   fi
-  df -h "$buildfolder/boot"
+  df -h "${buildFolder}/boot"
 }
 
-mount_image_file_root() { # imagefile buildfolder
+## Unmount RPi Image with userspace tools, for docker we use kpartx
+##
+##    umount_image_file_boot(String imageFile, String buildFolder)
+##
+umount_image_file_boot() {
+  local imageFile="$1"
+  local buildFolder="$2"
+
   if ! running_in_docker && ! running_on_github && ! is_pi; then
-    guestmount --format=raw -o uid=$EUID -a "$1" -m /dev/sda2 "$2/root"
+    guestunmount "${buildFolder}/boot"
   else
-    loop_prefix=$(kpartx -asv "$1" | grep -oE "loop([0-9]+)" | head -n 1)
-    e2fsck -y -f "/dev/mapper/${loop_prefix}p2" &> /dev/null
-    resize2fs "/dev/mapper/${loop_prefix}p2" &> /dev/null
-    mount -o rw -t ext4 "/dev/mapper/${loop_prefix}p2" "$buildfolder/root"
+    umount "${buildFolder}/boot"
+    kpartx -d "$imageFile"
   fi
-  df -h "$buildfolder/root"
 }
 
+## Mount RPi Image with userspace tools, for docker we use kpartx
+##
+##    mount_image_file_root(String imageFile, String buildFolder)
+##
+mount_image_file_root() {
+  local imageFile="$1"
+  local buildFolder="$2"
+  local loopPrefix
 
-# umount rpi image
-umount_image_file_boot() { # imagefile buildfolder
   if ! running_in_docker && ! running_on_github && ! is_pi; then
-    guestunmount "$2/boot"
+    guestmount --format=raw -o uid="$EUID" -a "$imageFile" -m /dev/sda2 "${buildFolder}/root"
   else
-    umount "$2/boot"
-    kpartx -d "$1"
+    loopPrefix="$(kpartx -asv "$imageFile" | grep -oE "loop([0-9]+)" | head -n 1)"
+    e2fsck -y -f "/dev/mapper/${loopPrefix}p2" &> /dev/null
+    resize2fs "/dev/mapper/${loopPrefix}p2" &> /dev/null
+    mount -o rw -t ext4 "/dev/mapper/${loopPrefix}p2" "${buildFolder}/root"
   fi
+  df -h "${buildFolder}/root"
 }
 
-# umount rpi image
-umount_image_file_root() { # imagefile buildfolder
+## Unmount RPi Image with userspace tools, for docker we use kpartx
+##
+##    umount_image_file_root(String imageFile, String buildFolder)
+##
+umount_image_file_root() {
+  local imageFile="$1"
+  local buildFolder="$2"
+
   if ! running_in_docker && ! running_on_github && ! is_pi; then
-    guestunmount "$2/root"
+    guestunmount "${buildFolder}/root"
   else
-    umount "$2/root"
-    kpartx -d "$1"
+    umount "${buildFolder}/root"
+    kpartx -d "$imageFile"
+  fi
+}
+
+## Make offline install modifications to code using systemd-nspawn
+##
+##    offline_install_modifications(String imageFile, String mountFolder)
+##
+offline_install_modifications() {
+  local imageFile="$1"
+  local mountFolder="$2"
+  local loopPrefix
+
+  if running_on_github; then
+    echo_process "Cacheing packages for offline install..."
+    loopPrefix="$(kpartx -asv "$imageFile" | grep -oE "loop([0-9]+)" | head -n 1)"
+    mount -o rw -t ext4 "/dev/mapper/${loopPrefix}p2" "$mountFolder"
+    mount -o rw -t vfat "/dev/mapper/${loopPrefix}p1" "${mountFolder}/boot"
+    systemd-nspawn --directory="$2" /opt/openhabian/includes/offline-install-modifications.bash &> /dev/null
+    sync
+    df -h "$mountFolder"
+    df -h "${mountFolder}/boot"
+    umount "${mountFolder}/boot"
+    umount "$mountFolder"
+    e2fsck -y -f "/dev/mapper/${loopPrefix}p2" &> /dev/null
+    zerofree "/dev/mapper/${loopPrefix}p2" &> /dev/null
+    sleep 30
+    kpartx -d "$imageFile"
   fi
 }
 
-## Grow root partition and file system of a downloaded Raspi OS image
+## Grow root partition and file system of a downloaded RaspiOS image
+## Root partition if #2 and sector size is 512 bytes for RaspiOS image
 ## Arguments: $1 = filename of image
 ##            $2 = number of MBs to grow image by
 ##
 ##    grow_image(String image, int extraSize)
 ##
 grow_image() {
-  local partStart
-  local partition
-
-  # root partition is #2 and sector size is 512 byte for the Raspi OS image
-  partition=2
-
-  dd if=/dev/zero bs=1M count="$2" oflag=append conv=notrunc of="$1" &> /dev/null
-  partStart=$(echo p|/sbin/fdisk "$1" | grep "$1"2 | awk '{print $2}')
-
-  /sbin/fdisk "$1" &> /dev/null <<EOF
-p
-d
-$partition
-n
-p
-$partition
-$partStart
-
-p
-w
-EOF
+  local partition="2"
+
+  qemu-img resize "$1" "+${2}M" &> /dev/null
+  echo ", +" | sfdisk -N "$partition" "$1" &> /dev/null
 }
 
 
@@ -188,17 +231,17 @@ EOF
 #### Build script start ####
 ############################
 
-timestamp=$(date +%Y%m%d%H%M)
-file_tag="" # marking output file for special builds
+timestamp="$(date +%Y%m%d%H%M)"
+fileTag="" # marking output file for special builds
 echo_process "This script will build the openHABian image file."
 
 # Identify hardware platform
 if [ "$1" == "rpi" ]; then
-  hw_platform="pi-raspios32"
+  hwPlatform="pi-raspios32"
   echo_process "Hardware platform: Raspberry Pi (rpi)"
 
 elif [ "$1" == "rpi64" ]; then
-  hw_platform="pi-raspios64beta"
+  hwPlatform="pi-raspios64beta"
   echo_process "Hardware platform: Raspberry Pi (rpi64) - BETA -"
 
 elif [ "$1" == "local-test" ]; then
@@ -225,18 +268,17 @@ fi
 
 # Check if a specific repository should be included
 if [ "$2" == "dev-git" ]; then # Use current git repo and branch as a development image
-  file_tag="custom"
+  fileTag="custom"
   get_git_repo
   echo_process "Injecting current branch and git repo when building this image, make sure to push local content to:"
-  echo_process "$clone_string"
-
+  echo_process "$cloneString"
 elif [ "$2" == "dev-url" ]; then # Use custom git server as a development image
-  file_tag="custom"
-  clone_string="$3 $4"
+  fileTag="custom"
+  cloneString="$3 $4"
   clonebranch="$3"
   repositoryurl="$4"
   echo_process "Injecting given git repo when building this image, make sure to push local content to:"
-  echo_process "$clone_string"
+  echo_process "$cloneString"
 elif [ -n "$2" ]; then
   usage
   exit 1
@@ -248,32 +290,32 @@ trap cleanup_build EXIT ERR
 cd "$(dirname "$0")" || (echo "$(dirname "$0") cannot be accessed."; exit 1)
 
 # Log everything to a file
-exec &> >(tee -a "openhabian-build-$timestamp.log")
+exec &> >(tee -a "openhabian-build-${timestamp}.log")
 
 # Load config, create temporary build folder, cleanup
-sourcefolder="build-image"
+sourceFolder="build-image"
 # shellcheck disable=SC1090
-source "${sourcefolder}/openhabian.${hw_platform}.conf"
-buildfolder="$(mktemp -d "${TMPDIR:-/tmp}"/openhabian-build-${hw_platform}-image.XXXXX)"
-imagefile="${buildfolder}/${hw_platform}.img"
-extrasize="300"			# grow image root by this number of MB
+source "${sourceFolder}/openhabian.${hwPlatform}.conf"
+buildFolder="$(mktemp -d "${TMPDIR:-/tmp}"/openhabian-build-${hwPlatform}-image.XXXXX)"
+imageFile="${buildFolder}/${hwPlatform}.img"
+extraSize="1000"			# grow image root by this number of MB
 
 # Build Raspberry Pi image
-if [[ $hw_platform == "pi-raspios32" ]] || [[ $hw_platform == "pi-raspios64beta" ]]; then
-  if [ "$hw_platform" == "pi-raspios64beta" ]; then
-    baseurl="https://downloads.raspberrypi.org/raspios_lite_arm64_latest"
+if [[ $hwPlatform == "pi-raspios32" ]] || [[ $hwPlatform == "pi-raspios64beta" ]]; then
+  if [ "$hwPlatform" == "pi-raspios64beta" ]; then
+    baseURL="https://downloads.raspberrypi.org/raspios_lite_arm64_latest"
     bits="64"
   else
-    baseurl="https://downloads.raspberrypi.org/raspios_lite_armhf_latest"
+    baseURL="https://downloads.raspberrypi.org/raspios_lite_armhf_latest"
     bits="32"
   fi
-  zipurl="$(curl "$baseurl" -s -L -I  -o /dev/null -w '%{url_effective}')"
-  zipfile="$(basename "$zipurl")"
+  zipURL="$(curl "$baseURL" -s -L -I  -o /dev/null -w '%{url_effective}')"
+  zipFile="$(basename "$zipURL")"
 
   # Prerequisites
   echo_process "Checking prerequisites... "
-  REQ_COMMANDS="git curl unzip crc32 dos2unix xz"
-  REQ_PACKAGES="git curl unzip libarchive-zip-perl dos2unix xz-utils"
+  requiredCommands="git curl wget unzip crc32 dos2unix xz qemu-img"
+  requiredPackages="git curl wget unzip libarchive-zip-perl dos2unix xz-utils qemu-utils"
   if running_in_docker || running_on_github || is_pi; then
     # in docker guestfstools are not used; do not install it and all of its prerequisites
     # -> must be run as root
@@ -281,106 +323,134 @@ if [[ $hw_platform == "pi-raspios32" ]] || [[ $hw_platform == "pi-raspios64beta"
       echo_process "For use with Docker or on RPi, this script must be run as root" 1>&2
       exit 1
     fi
-    REQ_COMMANDS+=" kpartx"
-    REQ_PACKAGES+=" kpartx"
+    requiredCommands+=" kpartx"
+    requiredPackages+=" kpartx"
   else
     # if not running in Docker not on a RPi, use userspace tools
-    REQ_COMMANDS+=" guestmount"
-    REQ_PACKAGES+=" libguestfs-tools"
+    requiredCommands+=" guestmount"
+    requiredPackages+=" libguestfs-tools"
   fi
-  check_command_availability_and_exit "$REQ_COMMANDS" "$REQ_PACKAGES"
+  check_command_availability_and_exit "$requiredCommands" "$requiredPackages"
 
-
-  if [[ -f $zipfile ]]; then
-    echo_process "Using local copy of Raspberry Pi OS ($bits-bit) image... "
-    cp "$zipfile" "$buildfolder/$zipfile"
+  if [[ -f $zipFile ]]; then
+    echo_process "Using local copy of Raspberry Pi OS (${bits}-bit) image... "
+    cp "$zipFile" "${buildFolder}/${zipFile}"
   else
-    echo_process "Downloading latest Raspberry Pi OS ($bits-bit) image (no local copy found)... "
-    curl -L "$baseurl" -o "$zipfile"
-    cp "$zipfile" "$buildfolder/$zipfile"
+    echo_process "Downloading latest Raspberry Pi OS (${bits}-bit) image (no local copy found)... "
+    curl -L "$baseURL" -o "$zipFile"
+    cp "$zipFile" "${buildFolder}/${zipFile}"
   fi
 
   echo_process "Verifying signature of downloaded image... "
-  curl -s "$zipurl".sig -o "$buildfolder"/"$zipfile".sig
+  curl -s "$zipURL".sig -o "$buildFolder"/"$zipFile".sig
   if ! gpg -q --keyserver keyserver.ubuntu.com --recv-key 0x8738CD6B956F460C; then echo "FAILED (download public key)"; exit 1; fi
-  if gpg -q --trust-model always --verify "$buildfolder/$zipfile".sig "$buildfolder/$zipfile"; then echo "OK"; else echo "FAILED (signature)"; exit 1; fi
+  if gpg -q --trust-model always --verify "${buildFolder}/${zipFile}".sig "${buildFolder}/${zipFile}"; then echo "OK"; else echo "FAILED (signature)"; exit 1; fi
 
   echo_process "Unpacking image... "
-  unzip -q "$buildfolder/$zipfile" -d "$buildfolder"
-  mv "$buildfolder"/*-raspios-*.img "$imagefile" || true
-
-  if [[ $extrasize -gt 0 ]]; then
-    echo_process "Growing root partition of the image by $extrasize MB... "
-    # shellcheck disable=SC2012
-    SIZEBEFORE=$(ls -sh "$imagefile"|awk '{print $1}')
-    grow_image "$imagefile" "$extrasize"
-    # shellcheck disable=SC2012
-    SIZEAFTER=$(ls -sh "$imagefile"|awk '{print $1}')
-    echo_process "Growing image form $SIZEBEFORE to $SIZEAFTER completed."
+  unzip -q "${buildFolder}/${zipFile}" -d "$buildFolder"
+  mv "$buildFolder"/*-raspios-*.img "$imageFile" || true
+
+  if [[ $extraSize -gt 0 ]]; then
+    echo_process "Growing root partition of the image by ${extraSize} MB... "
+    sizeBefore="$(( $(stat --format=%s "$imageFile") / 1024 / 1024 ))"
+    grow_image "$imageFile" "$extraSize"
+    sizeAfter="$(( $(stat --format=%s "$imageFile") / 1024 / 1024 ))"
+    echo_process "Growing image from ${sizeBefore} MB to ${sizeAfter} MB completed."
   fi
 
   echo_process "Mounting the image for modifications... "
-  mkdir -p "$buildfolder"/boot "$buildfolder"/root
-  mount_image_file_root "$imagefile" "$buildfolder"
+  mkdir -p "$buildFolder"/boot "$buildFolder"/root "$buildFolder"/mnt
+  mount_image_file_root "$imageFile" "$buildFolder"
 
   echo_process "Setting hostname... "
   # shellcheck disable=SC2154
-  sed -i "s/127.0.1.1.*/127.0.1.1 $hostname/" "$buildfolder"/root/etc/hosts
-  echo "$hostname" > "$buildfolder"/root/etc/hostname
+  sed -i "s/127.0.1.1.*/127.0.1.1 $hostname/" "$buildFolder"/root/etc/hosts
+  echo "$hostname" > "$buildFolder"/root/etc/hostname
 
   echo_process "Injecting 'openhabian-installer.service', 'first-boot.bash' and 'openhabian.conf'... "
-  cp "$sourcefolder"/openhabian-installer.service "$buildfolder"/root/etc/systemd/system/
-  ln -s "$buildfolder"/root/etc/systemd/system/openhabian-installer.service "$buildfolder"/root/etc/systemd/system/multi-user.target.wants/openhabian-installer.service
+  cp "$sourceFolder"/openhabian-installer.service "$buildFolder"/root/etc/systemd/system/
+  ln -s "$buildFolder"/root/etc/systemd/system/openhabian-installer.service "$buildFolder"/root/etc/systemd/system/multi-user.target.wants/openhabian-installer.service
 
-  # Open subshell to make sure we don't hurt the host system if for some reason $buildfolder is not properly set
+  # Open subshell to make sure we don't hurt the host system if for some reason $buildFolder is not properly set
   echo_process "Setting default runlevel multiuser.target and disabling autologin... "
   (
-    cd "$buildfolder"/root/etc/systemd/system/ || exit 1
+    cd "$buildFolder"/root/etc/systemd/system/ || exit 1
     rm -rf default.target
     ln -s ../../../lib/systemd/system/multi-user.target default.target
     rm -f getty@tty1.service.d/autologin.conf
   )
 
   echo_process "Cloning myself from ${repositoryurl:-https://github.com/openhab/openhabian.git}, ${clonebranch:-stable} branch... "
-  if ! [[ -d $buildfolder/root/opt/openhabian ]]; then
-    git clone "${repositoryurl:-https://github.com/openhab/openhabian.git}" "$buildfolder"/root/opt/openhabian &> /dev/null
-    git -C "$buildfolder"/root/opt/openhabian checkout "${clonebranch:-stable}" &> /dev/null
+  if ! [[ -d ${buildFolder}/root/opt/openhabian ]]; then
+    git clone "${repositoryurl:-https://github.com/openhab/openhabian.git}" "$buildFolder"/root/opt/openhabian &> /dev/null
+    git -C "$buildFolder"/root/opt/openhabian checkout "${clonebranch:-stable}" &> /dev/null
   fi
-  touch "$buildfolder"/root/opt/openHABian-install-inprogress
-  umount_image_file_root "$imagefile" "$buildfolder"
+  touch "$buildFolder"/root/opt/openHABian-install-inprogress
+
+  # Cache zram for offline install.
+  (
+    echo_process "Downloading zram..."
+    install_zram_code "${buildFolder}/root/opt/zram" &> /dev/null
+  )
+
+  # Cache Java for offline install.
+  (
+    # Source config to set Java option correctly, this cache currently only works for Zulu.
+    # shellcheck disable=SC1090
+    source "${sourceFolder}/openhabian.${hwPlatform}.conf"
+
+    echo_process "Downloading Java..."
+    # Using variable hw intended for CI only to force use of arm packages.
+    # java_zulu_fetch takes version/bits as parameter, but internally uses is_arm
+    # to decide if x86/64 or arm packages are downloaded. Parameter works for 32 and 64bit.
+    hwarch="armv7l" java_zulu_fetch "${java_opt:-Zulu8-32}" "$buildFolder"/root &> /dev/null
+    java_zulu_install_crypto_extension "$(find "$buildFolder"/root/opt/jdk/*/lib -type d -print -quit)/security" &> /dev/null
+  )
+
+  # Cache FireMotD for offline install.
+  (
+    echo_process "Downloading FireMotD..."
+    firemotd_download "${buildFolder}/root/opt" &> /dev/null
+  )
+
+  sync
+  umount_image_file_root "$imageFile" "$buildFolder"
+
+  mount_image_file_boot "$imageFile" "$buildFolder"
 
   echo_process "Reactivating SSH... "
-  mount_image_file_boot "$imagefile" "$buildfolder"
-  touch "$buildfolder"/boot/ssh
-  cp "$sourcefolder"/first-boot.bash "$buildfolder"/boot/first-boot.bash
-  touch "$buildfolder"/boot/first-boot.log
-  unix2dos -q -n "$sourcefolder"/openhabian.${hw_platform}.conf "$buildfolder"/boot/openhabian.conf
-  cp "$sourcefolder"/webserver.bash "$buildfolder"/boot/webserver.bash
-
-  # Injecting development git repo if clone_string is set and watermark build
-  if [[ -n "${clone_string+x}" ]]; then
-    inject_build_repo "$buildfolder"/boot/first-boot.bash
+  touch "$buildFolder"/boot/ssh
+  cp "$sourceFolder"/first-boot.bash "$buildFolder"/boot/first-boot.bash
+  touch "$buildFolder"/boot/first-boot.log
+  unix2dos -q -n "$sourceFolder"/openhabian.${hwPlatform}.conf "$buildFolder"/boot/openhabian.conf
+  cp "$sourceFolder"/webserver.bash "$buildFolder"/boot/webserver.bash
+
+  # Injecting development git repo if cloneString is set and watermark build
+  if [[ -n "${cloneString+x}" ]]; then
+    inject_build_repo "$buildFolder"/boot/first-boot.bash
   fi
 
   echo_process "Closing up image file... "
   sync
-  umount_image_file_boot "$imagefile" "$buildfolder"
+  umount_image_file_boot "$imageFile" "$buildFolder"
+
+  offline_install_modifications "$imageFile" "${buildFolder}/mnt"
 fi
 
 echo_process "Moving image and cleaning up... "
 shorthash="$(git log --pretty=format:'%h' -n 1)"
-crc32checksum=$(crc32 "$imagefile")
-destination="openhabian-${hw_platform}-${timestamp}-git${file_tag}${shorthash}-crc${crc32checksum}.img"
-mv -v "$imagefile" "$destination"
-rm -rf "$buildfolder"
+crc32checksum="$(crc32 "$imageFile")"
+destination="openhabian-${hwPlatform}-${timestamp}-git${fileTag}${shorthash}-crc${crc32checksum}.img"
+mv -v "$imageFile" "$destination"
+rm -rf "$buildFolder"
 
 echo_process "Compressing image... "
 # speedup compression, T0 will use all cores and should be supported by reasonably new versions of xz
-xz --verbose --compress --keep -T0 "$destination"
-crc32checksum="$(crc32 "$destination.xz")"
-mv "${destination}.xz" "openhabian-${hw_platform}-${timestamp}-git${file_tag}${shorthash}-crc${crc32checksum}.img.xz"
+xz --verbose --compress --keep -9 -T0 "$destination"
+crc32checksum="$(crc32 "${destination}.xz")"
+mv "${destination}.xz" "openhabian-${hwPlatform}-${timestamp}-git${fileTag}${shorthash}-crc${crc32checksum}.img.xz"
 
 echo_process "Finished! The results:"
-ls -alh "openhabian-$hw_platform-$timestamp"*
+ls -alh "openhabian-${hwPlatform}-${timestamp}"*
 
 # vim: filetype=sh
diff --git a/functions/backup.bash b/functions/backup.bash
index 409e69954..78717a79d 100644
--- a/functions/backup.bash
+++ b/functions/backup.bash
@@ -432,6 +432,11 @@ mirror_SD() {
 ##   setup_mirror_SD()
 ##
 setup_mirror_SD() {
+  if [[ -n "$UNATTENDED" ]] && [[ -z "$backupdrive" ]]; then
+    echo "$(timestamp) [openHABian] Setting up automated SD mirroring and backup... CANCELED (no configuration provided)"
+    return 0
+  fi
+
   local dest
   local srcSize
   local destSize
@@ -440,16 +445,17 @@ setup_mirror_SD() {
   local storageDir="${storagedir:-/storage}"
   local sizeError="your destination SD card device does not have enough space, it needs to have at least twice as much as the source"
   local infoText1="DANGEROUS OPERATION, USE WITH PRECAUTION!\\n\\nThis will *copy* your system root from your SD card to a USB attached card writer device. Are you sure"
-  local infoText2="is an SD card writer device equipped with a dispensible SD card ? Are you this will destroy all data on that card and you want to proceed writing to this device ?"
-
+  local infoText2="is an SD card writer device equipped with a dispensible SD card? Are you sure, this will destroy all data on that card and you want to proceed writing to this device?"
 
   echo -n "$(timestamp) [openHABian] Setting up automated SD mirroring and backup... "
+
   if [[ "$1" == "remove" ]]; then
     cond_redirect systemctl disable sdrsync.service sdrawcopy.service sdrsync.timer sdrawcopy.timer
     rm -f ${serviceTargetDir}/sdr*.{service,timer}
     cond_redirect systemctl -q daemon-reload &> /dev/null
     return 0
   fi
+
   if [[ "$1" != "install" ]]; then echo "FAILED"; return 1; fi
 
   if ! is_pi; then
@@ -461,11 +467,8 @@ setup_mirror_SD() {
 
   mkdir -p "${storageDir}"
   if cond_redirect apt-get install --yes gdisk; then echo "OK"; else echo "FAILED (install gdisk)"; return 1; fi
-
-  # shellcheck disable=SC2154
-  if [[ -n "$UNATTENDED" ]] && [[ -z "$backupdrive" ]]; then return 0; fi
-
   if ! cond_redirect install -m 755 "${BASEDIR:-/opt/openhabian}"/includes/set-partuuid /usr/local/sbin; then echo "FAILED (install set-partuuid)"; return 1; fi
+
   if [[ -n "$INTERACTIVE" ]]; then
     select_blkdev "^sd" "Setup SD mirroring" "Select USB device to copy the internal SD card data to"
     if [[ -z "$retval" ]]; then return 0; fi
diff --git a/functions/helpers.bash b/functions/helpers.bash
index dac9f6c28..40e9b3417 100644
--- a/functions/helpers.bash
+++ b/functions/helpers.bash
@@ -439,6 +439,6 @@ select_blkdev() {
   else
     ((count=${#array[@]} + 8))
     # shellcheck disable=SC2034
-    retval="$(whiptail --title "$2" --cancel-button Cancel --ok-button Select --menu "\n${3}" ${count} 76 0 "${array[@]}" 3>&1 1>&2 2>&3)"
+    retval="$(whiptail --title "$2" --cancel-button Cancel --ok-button Select --menu "\n${3}" "${count}" 76 0 "${array[@]}" 3>&1 1>&2 2>&3)"
   fi
 }
diff --git a/functions/java-jre.bash b/functions/java-jre.bash
index 14fc42915..7d0987dd3 100644
--- a/functions/java-jre.bash
+++ b/functions/java-jre.bash
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+# shellcheck disable=SC2119,SC2120
 
 ## Install appropriate Java version based on current choice.
 ## Valid arguments: "Adopt11", "Zulu8-32", "Zulu8-64", "Zulu11-32", or "Zulu11-64"
@@ -116,7 +117,12 @@ java_zulu_prerequisite() {
     if is_aarch64 && [[ $(getconf LONG_BIT) == 64 ]]; then
       if dpkg -s 'libc6:arm64' 'libstdc++6:arm64' 'zlib1g:arm64' &> /dev/null; then echo "OK"; return 0; fi
       dpkg --add-architecture arm64
-      if ! cond_redirect apt-get update; then echo "FAILED (update apt lists)"; return 1; fi
+      if ! cond_redirect apt-get update; then
+        echo "FAILED (update apt lists)"
+        if [[ -z $OFFLINE ]]; then
+          return 1
+        fi
+      fi
       if cond_redirect apt-get install --yes libc6:arm64 libstdc++6:arm64 zlib1g:arm64; then echo "OK"; else echo "FAILED"; return 1; fi
     elif is_x86_64 && [[ $(getconf LONG_BIT) == 64 ]]; then
       if dpkg -s 'libc6:amd64' 'libstdc++6:amd64' 'zlib1g:amd64' &> /dev/null; then echo "OK"; return 0; fi
@@ -128,7 +134,12 @@ java_zulu_prerequisite() {
     if is_arm; then
       if dpkg -s 'libc6:armhf' 'libstdc++6:armhf' 'zlib1g:armhf' &> /dev/null; then echo "OK"; return 0; fi
       dpkg --add-architecture armhf
-      if ! cond_redirect apt-get update; then echo "FAILED (update apt lists)"; return 1; fi
+      if ! cond_redirect apt-get update; then
+        echo "FAILED (update apt lists)"
+        if [[ -z $OFFLINE ]]; then
+          return 1
+        fi
+      fi
       if cond_redirect apt-get install --yes libc6:armhf libstdc++6:armhf zlib1g:armhf; then echo "OK"; else echo "FAILED"; return 1; fi
     else
       if dpkg -s 'libc6:i386' 'libstdc++6:i386' 'zlib1g:i386' &> /dev/null; then echo "OK"; return 0; fi
@@ -233,14 +244,14 @@ java_zulu_install() {
 ## Fetch Java Zulu 8 directly from Azul API v1
 ## Valid arguments: "Zulu8-32", "Zulu8-64", "Zulu11-32", or "Zulu11-64"
 ##
-##    java_zulu_fetch(String type)
+##    java_zulu_fetch(String type, String prefix)
 ##
 java_zulu_fetch() {
   local downloadLink
   local jdkInstallLocation
   local link
 
-  jdkInstallLocation="/opt/jdk"
+  jdkInstallLocation="${2}/opt/jdk"
   link="https://api.azul.com/zulu/download/community/v1.0/bundles/latest/binary/?os=linux&ext=tar.gz&javafx=false"
 
   if [[ $1 == "Zulu8-32" ]]; then
@@ -274,7 +285,7 @@ java_zulu_fetch() {
   fi
   if [[ -z $downloadLink ]]; then echo "FAILED (download link)"; return 1; fi
 
-  if ! mkdir -p $jdkInstallLocation; then echo "FAILED (create directory)"; return 1; fi
+  if ! mkdir -p "$jdkInstallLocation"; then echo "FAILED (create directory)"; return 1; fi
   if ! rm -rf "${jdkInstallLocation:?}"/*; then echo "FAILED (clean directory)"; return 1; fi
   if ! cond_redirect wget -O "$jdkInstallLocation"/zulu.tar.gz "$downloadLink"; then echo "FAILED (download)"; rm -rf "${jdkInstallLocation:?}"/*; return 1; fi
   if ! cond_redirect tar -xpzf "$jdkInstallLocation"/zulu.tar.gz -C "$jdkInstallLocation"; then echo "FAILED (extract)"; rm -rf "${jdkInstallLocation:?}"/*; return 1; fi
@@ -387,13 +398,18 @@ java_zulu_enterprise_apt() {
 
 ## Install Zulu Cryptography Extension Kit to enable cryptos using more then 128 bits
 ##
-##    java_zulu_install_crypto_extension()
+##    java_zulu_install_crypto_extension(String path)
 ##
 java_zulu_install_crypto_extension() {
+  if [[ -n $OFFLINE ]]; then
+    echo "$(timestamp) [openHABian] Using cached Java Zulu CEK to enable unlimited cipher strength... OK"
+    return 0
+  fi
+
   local jdkSecurity
   local policyTempLocation
 
-  jdkSecurity="$(realpath /usr/bin/java | sed 's|/java||')/../lib/security"
+  jdkSecurity="${1:-"$(realpath /usr/bin/java | sed 's|/java||')/../lib/security"}"
   policyTempLocation="$(mktemp -d "${TMPDIR:-/tmp}"/openhabian.XXXXX)"
 
   echo -n "$(timestamp) [openHABian] Installing Java Zulu CEK to enable unlimited cipher strength... "
diff --git a/functions/nodejs-apps.bash b/functions/nodejs-apps.bash
index 1ff03438f..96d59ee41 100644
--- a/functions/nodejs-apps.bash
+++ b/functions/nodejs-apps.bash
@@ -20,21 +20,31 @@ nodejs_setup() {
   myDistro="$(lsb_release -sc)"
   temp="$(mktemp "${TMPDIR:-/tmp}"/openhabian.XXXXX)"
 
-  if is_armv6l; then
+  if [[ -z $PREOFFLINE ]] && is_armv6l; then
     echo -n "$(timestamp) [openHABian] Installing NodeJS... "
     if ! cond_redirect wget -qO "$temp" "$link"; then echo "FAILED (download)"; rm -f "$temp"; return 1; fi
     if ! cond_redirect tar -Jxf "$temp" --strip-components=1 -C /usr; then echo "FAILED (extract)"; rm -f "$temp"; return 1; fi
     if cond_redirect rm -f "$temp"; then echo "OK"; else echo "FAILED (cleanup)"; return 1; fi
   else
-    if ! add_keys "https://deb.nodesource.com/gpgkey/nodesource.gpg.key"; then return 1; fi
-
-    echo -n "$(timestamp) [openHABian] Adding NodeSource repository to apt... "
-    echo "deb https://deb.nodesource.com/node_12.x $myDistro main" > /etc/apt/sources.list.d/nodesource.list
-    echo "deb-src https://deb.nodesource.com/node_12.x $myDistro main" >> /etc/apt/sources.list.d/nodesource.list
-    if cond_redirect apt-get update; then echo "OK"; else echo "FAILED (update apt lists)"; return 1; fi
+    if [[ -z $OFFLINE ]]; then
+      if ! add_keys "https://deb.nodesource.com/gpgkey/nodesource.gpg.key"; then return 1; fi
+
+      echo -n "$(timestamp) [openHABian] Adding NodeSource repository to apt... "
+      echo "deb https://deb.nodesource.com/node_12.x $myDistro main" > /etc/apt/sources.list.d/nodesource.list
+      echo "deb-src https://deb.nodesource.com/node_12.x $myDistro main" >> /etc/apt/sources.list.d/nodesource.list
+      if [[ -n $PREOFFLINE ]]; then
+        if cond_redirect apt-get --quiet update; then echo "OK"; else echo "FAILED (update apt lists)"; return 1; fi
+      else
+        if cond_redirect apt-get update; then echo "OK"; else echo "FAILED (update apt lists)"; return 1; fi
+      fi
+    fi
 
     echo -n "$(timestamp) [openHABian] Installing NodeJS... "
-    if cond_redirect apt-get install --yes nodejs; then echo "OK"; else echo "FAILED"; return 1; fi
+    if [[ -n $PREOFFLINE ]]; then
+      if cond_redirect apt-get --quiet install --download-only --yes nodejs; then echo "OK"; else echo "FAILED"; return 1; fi
+    else
+      if cond_redirect apt-get install --yes nodejs; then echo "OK"; else echo "FAILED"; return 1; fi
+    fi
   fi
 }
 
@@ -44,7 +54,7 @@ nodejs_setup() {
 ##
 frontail_setup() {
   local frontailBase
-  local frontailUser=frontail
+  local frontailUser="frontail"
 
   if ! [[ -x $(command -v npm) ]] || [[ $(node --version) != "v12"* ]] || is_armv6l; then
     echo -n "$(timestamp) [openHABian] Installing Frontail prerequsites (NodeJS)... "
diff --git a/functions/openhab.bash b/functions/openhab.bash
index c15a17ad9..23f741ae8 100644
--- a/functions/openhab.bash
+++ b/functions/openhab.bash
@@ -76,14 +76,19 @@ openhab2_setup() {
     echo "OK"
   fi
 
-  if ! add_keys "https://bintray.com/user/downloadSubjectPublicKey?username=openhab"; then return 1; fi
+  if [[ -z $OFFLINE ]]; then
+    if ! add_keys "https://bintray.com/user/downloadSubjectPublicKey?username=openhab"; then return 1; fi
 
-  echo "$repo" > /etc/apt/sources.list.d/openhab2.list
+    echo "$repo" > /etc/apt/sources.list.d/openhab2.list
 
-  echo -n "$(timestamp) [openHABian] Installing selected openHAB version... "
-  if ! cond_redirect apt-get update; then echo "FAILED (update apt lists)"; return 1; fi
-  openhabVersion="$(apt-cache madison openhab2 | head -n 1 | cut -d'|' -f2 | xargs)"
-  if cond_redirect apt-get install --allow-downgrades --yes "openhab2=${openhabVersion}" "openhab2-addons=${openhabVersion}"; then echo "OK"; else echo "FAILED"; return 1; fi
+    echo -n "$(timestamp) [openHABian] Installing selected openHAB version... "
+    if ! cond_redirect apt-get update; then echo "FAILED (update apt lists)"; return 1; fi
+    openhabVersion="$(apt-cache madison openhab2 | head -n 1 | cut -d'|' -f2 | xargs)"
+    if cond_redirect apt-get install --allow-downgrades --yes "openhab2=${openhabVersion}" "openhab2-addons=${openhabVersion}"; then echo "OK"; else echo "FAILED"; return 1; fi
+  else
+    echo -n "$(timestamp) [openHABian] Installing cached openHAB version... "
+    if cond_redirect apt-get install --yes openhab2 openhab2-addons; then echo "OK"; else echo "FAILED"; return 1; fi
+  fi
 
   echo -n "$(timestamp) [openHABian] Setting up openHAB service... "
   if ! cond_redirect systemctl -q daemon-reload &> /dev/null; then echo "FAILED (daemon-reload)"; return 1; fi
diff --git a/functions/openhabian.bash b/functions/openhabian.bash
index 9f143d48b..ac1b886e1 100644
--- a/functions/openhabian.bash
+++ b/functions/openhabian.bash
@@ -25,6 +25,7 @@ get_git_revision() {
 install_cleanup() {
   echo -n "$(timestamp) [openHABian] Cleaning up... "
   if ! cond_redirect systemctl -q daemon-reload &> /dev/null; then echo "FAILED (daemon-reload)"; return 1; fi
+  if ! cond_redirect apt-get clean; then echo "FAILED (apt-get clean)"; return 1; fi
   if cond_redirect apt-get autoremove --yes; then echo "OK"; else echo "FAILED"; return 1; fi
 }
 
diff --git a/functions/packages.bash b/functions/packages.bash
index 3d065c56c..50ee789ba 100644
--- a/functions/packages.bash
+++ b/functions/packages.bash
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+# shellcheck disable=SC2120
 
 ## Function for installing samba for remote access of folders.
 ## This function can be invoked either INTERACTIVE with userinterface or UNATTENDED.
@@ -29,50 +30,63 @@ samba_setup() {
   if cond_redirect systemctl enable --now smbd.service &> /dev/null; then echo "OK"; else echo "FAILED (enable service)"; return 1; fi
 }
 
+## Function for downloading FireMotD to current system
+##
+##    firemotd_download(String prefix)
+##
+firemotd_download() {
+  echo -n "$(timestamp) [openHABian] Downloading FireMotD... "
+  if ! [[ -d "${1}/FireMotD" ]]; then
+    cond_echo "\\nFresh Installation... "
+    if cond_redirect git clone https://github.com/OutsideIT/FireMotD.git "${1}/FireMotD"; then echo "OK"; else echo "FAILED (git clone)"; return 1; fi
+  else
+    cond_echo "\\nUpdate... "
+    if cond_redirect update_git_repo "${1}/FireMotD" "master"; then echo "OK"; else echo "FAILED (update git repo)"; return 1; fi
+  fi
+}
+
 ## Function for installing FireMotD which displays the system overview on login.
 ## This function can be invoked either INTERACTIVE with userinterface or UNATTENDED.
 ##
 ##    firemotd_setup()
 ##
 firemotd_setup() {
-  local temp
-  local targetDir="/etc/systemd/system/"
+  if running_in_docker || running_on_github; then return 0; fi
 
-  temp="$(mktemp "${TMPDIR:-/tmp}"/openhabian.XXXXX)"
+  local firemotdDir="/opt/FireMotD"
+  local targetDir="/etc/systemd/system/"
 
-  if ! dpkg -s 'bc' 'sysstat' 'jq' 'moreutils' &> /dev/null; then
+  if ! dpkg -s 'bc' 'sysstat' 'jq' 'moreutils' 'make' &> /dev/null; then
     echo -n "$(timestamp) [openHABian] Installing FireMotD required packages (bc, sysstat, jq, moreutils)... "
-    if cond_redirect apt-get install --yes bc sysstat jq moreutils; then echo "OK"; else echo "FAILED"; return 1; fi
+    if cond_redirect apt-get install --yes bc sysstat jq moreutils make; then echo "OK"; else echo "FAILED"; return 1; fi
   fi
 
-  echo -n "$(timestamp) [openHABian] Downloading FireMotD... "
-  if cond_redirect wget -O "$temp" https://raw.githubusercontent.com/OutsideIT/FireMotD/master/FireMotD; then
-    echo "OK"
-  else
-    echo "FAILED"
-    rm -f "$temp"
-    return 1
+  if ! firemotd_download /opt; then
+    if [[ -z $OFFLINE ]]; then
+       return 1
+    fi
   fi
 
-  echo -n "$(timestamp) [openHABian] Setting up FireMotD... "
-  chmod 755 "$temp"
-  if cond_redirect "$temp" -I; then echo "OK"; rm -f "$temp"; else echo "FAILED"; rm -f "$temp"; return 1; fi
+  echo -n "$(timestamp) [openHABian] Installing FireMotD... "
+  if ! cond_redirect make --always-make --directory="$firemotdDir" install; then echo "FAILED (install FireMotD)"; return 1; fi
+  if cond_redirect make --always-make --directory="$firemotdDir" bash_completion; then echo "OK"; else echo "FAILED (install FireMotD bash completion)"; return 1; fi
 
   echo -n "$(timestamp) [openHABian] Generating FireMotD theme... "
+  if ! cond_redirect FireMotD -S -D all; then echo "FAILED (generate FireMotD)"; return 1; fi
   if cond_redirect FireMotD -G Gray; then echo "OK"; else echo "FAILED"; return 1; fi
 
-  if ! grep -q "FireMotD" /home/"${username:-openhabian}"/.bash_profile; then
+  if ! grep -qs "FireMotD" /home/"${username:-openhabian}"/.bash_profile; then
     echo -n "$(timestamp) [openHABian] Make FireMotD display on login... "
     if echo -e "\\necho\\nFireMotD --theme Gray \\necho" >> /home/"${username:-openhabian}"/.bash_profile; then echo "OK"; else echo "FAILED"; return 1; fi
   fi
 
   echo -n "$(timestamp) [openHABian] Setting up FireMotD apt updates count service... "
   cond_echo "\\nMake FireMotD check for new updates every night... "
-  if cond_redirect cp "${BASEDIR}"/includes/firemotd.* "$targetDir"/; then echo "OK"; else echo "FAILED"; return 1; fi
+  if cond_redirect cp "${BASEDIR}"/includes/firemotd.* "$targetDir"; then echo "OK"; else echo "FAILED"; return 1; fi
   if ! cond_redirect systemctl -q daemon-reload &> /dev/null; then echo "FAILED (daemon-reload)"; return 1; fi
   if ! cond_redirect systemctl enable firemotd.service &> /dev/null; then echo "FAILED (service enable)"; return 1; fi
   cond_echo "\\nMake FireMotD check for new updates after using apt... "
-  echo "DPkg::Post-Invoke { \"if [ -x /usr/local/bin/FireMotD ]; then echo -n 'Updating FireMotD available updates count ... '; /bin/bash /usr/local/bin/FireMotD --skiprepoupdate -S; echo ''; fi\"; };" > /etc/apt/apt.conf.d/15firemotd
+  if ! cond_redirect install -m 644 "${BASEDIR:-/opt/openhabian}"/includes/15firemotd /etc/apt/apt.conf.d/; then echo "FAILED (apt configuration)"; return 1; fi
   cond_echo "\\nInitial FireMotD updates check"
   if cond_redirect FireMotD -S; then echo "OK"; else echo "FAILED"; return 1; fi
 }
@@ -83,6 +97,11 @@ firemotd_setup() {
 ##    exim_setup()
 ##
 exim_setup() {
+  if [[ -n $UNATTENDED ]] && [[ -z $relayuser ]]; then
+    echo "$(timestamp) [openHABian] Beginning Mail Transfer Agent setup... CANCELED (no configuration provided)"
+    return 0
+  fi
+
   local updateEximTemplate="${BASEDIR:-/opt/openhabian}/includes/update-exim4.conf.conf-template"
   local eximConfig="/etc/exim4/update-exim4.conf.conf"
   local eximPasswd="/etc/exim4/passwd.client"
diff --git a/functions/system.bash b/functions/system.bash
index 0139907bf..b15445e0f 100644
--- a/functions/system.bash
+++ b/functions/system.bash
@@ -46,16 +46,16 @@ needed_packages() {
   local bluetoothPackages="bluez python3-dev libbluetooth-dev raspberrypi-sys-mods pi-bluetooth"
 
   # Install apt-transport-https - update packages through https repository
-  # Install bc + sysstat - needed for FireMotD
+  # Install bc/sysstat/jq/moreutils - needed for FireMotD
   # Install avahi-daemon - hostname based discovery on local networks
   # Install python3/python3-pip/python3-wheel/python3-setuptools - for python packages
   echo -n "$(timestamp) [openHABian] Installing additional needed packages... "
-  if cond_redirect apt-get install --yes apt-transport-https bc sysstat \
-    avahi-daemon python3 python3-pip python3-wheel python3-setuptools \
+  if cond_redirect apt-get install --yes apt-transport-https bc sysstat jq \
+    moreutils avahi-daemon python3 python3-pip python3-wheel python3-setuptools \
     avahi-autoipd fontconfig; \
   then echo "OK"; else echo "FAILED"; return 1; fi
 
-  if is_pizerow || is_pithree || is_pithreeplus || is_pifour; then
+  if is_pizerow || is_pithree || is_pithreeplus || is_pifour && [[ -z $PREOFFLINE ]]; then
     echo -n "$(timestamp) [openHABian] Installing additional bluetooth packages... "
     # phython3-bluez is not available in stretch so only add it if we are runnning on buster or later
     if ! is_stretch; then
diff --git a/includes/15firemotd b/includes/15firemotd
new file mode 100644
index 000000000..8bb5ee98c
--- /dev/null
+++ b/includes/15firemotd
@@ -0,0 +1,3 @@
+DPkg::Post-Invoke {
+  "if [ -x /usr/local/bin/FireMotD ]; then echo -n 'Updating FireMotD available updates count ... '; /usr/local/bin/FireMotD --skiprepoupdate -S; echo ''; fi";
+};
diff --git a/includes/firemotd.service b/includes/firemotd.service
index 2d01c6ab8..532416a72 100644
--- a/includes/firemotd.service
+++ b/includes/firemotd.service
@@ -1,5 +1,5 @@
 [Unit]
-Description=periodic FireMotD stats regeneration
+Description=Periodic FireMotD stats regeneration
 
 [Service]
 Type=oneshot
diff --git a/includes/offline-install-modifications.bash b/includes/offline-install-modifications.bash
new file mode 100755
index 000000000..cb52ca84a
--- /dev/null
+++ b/includes/offline-install-modifications.bash
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+export BASEDIR="/opt/openhabian"
+export DEBIAN_FRONTEND="noninteractive"
+export PREOFFLINE="1"
+
+source /opt/openhabian/functions/helpers.bash
+add_keys "https://bintray.com/user/downloadSubjectPublicKey?username=openhab"
+echo "deb https://dl.bintray.com/openhab/apt-repo2 stable main" > /etc/apt/sources.list.d/openhab2.list
+apt-get --quiet update
+apt-get --quiet upgrade --yes
+apt-get --quiet install --download-only --yes libattr1-dev libc6 libstdc++6 \
+  zlib1g make openhab2 openhab2-addons samba amanda-common amanda-server \
+  amanda-client exim4 dnsutils mailutils gdisk screen vim nano mc vfu \
+  bash-completion htop curl wget multitail git util-linux bzip2 zip unzip \
+  xz-utils software-properties-common man-db whiptail acl usbutils dirmngr \
+  arping apt-transport-https bc sysstat jq moreutils avahi-daemon python3 \
+  python3-pip python3-wheel python3-setuptools avahi-autoipd fontconfig
+source /opt/openhabian/functions/nodejs-apps.bash
+nodejs_setup
+apt-get --quiet autoremove --yes
+exit
diff --git a/openhabian-setup.sh b/openhabian-setup.sh
index 533c1d10f..cb12edd1e 100755
--- a/openhabian-setup.sh
+++ b/openhabian-setup.sh
@@ -82,7 +82,7 @@ config_ipv6
 
 if [[ -n "$UNATTENDED" ]]; then
   # apt/dpkg commands will not try interactive dialogs
-  export DEBIAN_FRONTEND=noninteractive
+  export DEBIAN_FRONTEND="noninteractive"
   wait_for_apt_to_finish_update
   load_create_config
   change_swapsize
diff --git a/openhabian.conf.dist b/openhabian.conf.dist
index d1ad8d0e8..00bf10e3a 100644
--- a/openhabian.conf.dist
+++ b/openhabian.conf.dist
@@ -25,6 +25,12 @@ system_default_locale="en_US.UTF-8"
 wifi_ssid=""
 wifi_psk=""
 
+# Wi-Fi setting. Select a two-letter country code suitable for your location
+# E.g. US (default), DE, AU, NZ...
+# You may infringe on local legislature otherwise
+# See https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2 or /usr/share/zoneinfo/zone.tab
+wifi_country=""
+
 # Eventually disable all IPv6 e.g. on installation problems
 # values: "enable", "disable"
 ipv6=enable
@@ -71,6 +77,5 @@ java_opt=Zulu8-64
 #relaypass=secret
 #smarthost=smtp.gmail.com
 #smartport=587
-#
 
 # vim: filetype=sh