diff --git a/de-p1st-installer.sh b/de-p1st-installer.sh
index 8db9e50..6d211da 100755
--- a/de-p1st-installer.sh
+++ b/de-p1st-installer.sh
@@ -1,12 +1,14 @@
 #!/bin/bash
+set -e
+set -u
 
 # load config
-source /etc/de-p1st-installer/installer.cfg       || { exit 1; }
+source /etc/de-p1st-installer/installer.cfg
 
 # load functions
-source /usr/lib/de-p1st-installer/util.sh         || { exit 1; }
-source /usr/lib/de-p1st-installer/user-input.sh   || { exit 1; }
-source /usr/lib/de-p1st-installer/block-device.sh || { exit 1; }
+source /usr/lib/de-p1st-installer/util.sh
+source /usr/lib/de-p1st-installer/user-input.sh
+source /usr/lib/de-p1st-installer/block-device.sh
 
 function main() {
   # @pre
@@ -14,59 +16,59 @@ function main() {
   # @post
   #   installation finished
 
-  check_network  || return $?
-  system_time || return $?
+  check_network
+  system_time
   # in: BOOT_FIRMWARE, FS, HOSTNAME, USERNAME, USER_PWD, FDE, LUKS_PWD; (all variables are optional)
   # out: BOOT_FIRMWARE, FS, HOSTNAME, USERNAME, USER_PWD, FDE, LUKS_PWD (if FDE='true')
-  get_user_input || return $?
+  get_user_input
   # in: CPU_VENDOR (optional)
   # out: CPU_VENDOR
-  get_cpu_vendor || return $?
+  get_cpu_vendor
 
   # in: FS
   # out: FS_DEFAULT_MOUNT_OPTIONS
-  get_default_mount_options    || return $?
+  get_default_mount_options
   # in: FS
   # out: FS_ADDITIONAL_MOUNT_OPTIONS
-  get_additional_mount_options || return $?
+  get_additional_mount_options
 
   # in: TARGET_BLOCK_DEVICE, BOOT_FIRMWARE
   # out: BOOT_PART, LUKS_PART
-  partition || return $?
+  partition
   # in: BOOT_FIRMWARE, BOOT_PART, LUKS_PART, FDE, LUKS_PWD, FS
   # out: LUKS_PART_UUID (if FDE='true'), DATA_PART
-  format    || return $?
+  format
 
   # Combine default and additional mount options
   # out: FS_MOUNT_OPTIONS
   {
-    TMP1=("${FS_DEFAULT_MOUNT_OPTIONS[@]}" "${FS_ADDITIONAL_MOUNT_OPTIONS[@]}") || return $?
+    TMP1=("${FS_DEFAULT_MOUNT_OPTIONS[@]}" "${FS_ADDITIONAL_MOUNT_OPTIONS[@]}")
     # Join array elements by ","
-    join_by ',' TMP1 FS_MOUNT_OPTIONS || return $?
+    join_by ',' TMP1 FS_MOUNT_OPTIONS
   }
 
-  mount_partitions || return $?
+  mount_partitions
 
   # in: BOOT_FIRMWARE, PACSTRAP_INTERACTIVE (optional)
-  run_pacstrap  || return $?
+  run_pacstrap
   # in: FS
-  run_genfstab  || return $?
+  run_genfstab
 
   # in: HOSTNAME, FQDN (optional), STATIC_IP (optional), IPV6_CAPABLE (optional)
-  config_hostname_and_hosts || return $?
+  config_hostname_and_hosts
   # in: USERNAME, USER_PWD, ROOT_PWD (optional)
-  user_and_pwd  || return $?
+  user_and_pwd
 
-  sudo arch-chroot /mnt mkinitcpio -P || return $?
+  sudo arch-chroot /mnt mkinitcpio -P
   # in: TARGET_BLOCK_DEVICE, FDE, LUKS_PART_UUID
-  bootloader || return $?
+  bootloader
 
   if [ "${LEAVE_MOUNTED}" = 'true' ]; then
     echo 'Leaving partitions below /mnt mounted and '"${DATA_PART}"' opened.'
   else
-    sudo umount -R /mnt || return $?
-    if [ "${FDE}" = 'true' ] ; then
-      sudo cryptsetup luksClose "$(basename "${DATA_PART}")" || return $?
+    sudo umount -R /mnt
+    if [ "${FDE}" = 'true' ]; then
+      sudo cryptsetup luksClose "$(basename "${DATA_PART}")"
     fi
   fi
   echo 'Finished installation without errors!'
@@ -96,7 +98,7 @@ function increase_cow_space() {
   }
 
   echo 'Increasing cowspace partition of live medium ...'
-  sudo mount -o remount,size=2G /run/archiso/cowspace || return $?
+  sudo mount -o remount,size=2G /run/archiso/cowspace
 }
 
 function get_user_input() {
@@ -109,8 +111,8 @@ function get_user_input() {
   #   FDE: 'true' | 'false'
   #   LUKS_PWD: only set if FDE='true'
 
-  get_block_devices_with_size || return $?
-  single_choice_if_empty  TARGET_BLOCK_DEVICE 'Select target device for installation' BLOCK_DEVICE_SIZES || return $?
+  get_block_devices_with_size
+  single_choice_if_empty  TARGET_BLOCK_DEVICE 'Select target device for installation' BLOCK_DEVICE_SIZES
 
   if [ "${BOOT_FIRMWARE}" = 'autodetect' ]; then
     # Detect boot firmware type: https://askubuntu.com/a/162573
@@ -128,43 +130,43 @@ function get_user_input() {
   else  # If $BOOT_FIRMWARE is empty: Let user select BIOS type
     TMP1=('uefi' 'Newer mainboards' \
           'bios' 'Legacy BIOS on older mainboards')
-    single_choice_if_empty  BOOT_FIRMWARE 'Select your bios type' TMP1 || return $?
+    single_choice_if_empty  BOOT_FIRMWARE 'Select your bios type' TMP1
   fi
 
   TMP1=('BTRFS' 'Allows snapshots and dynamic extension of the FS' \
         'EXT4'  'Default FS of many distributions' \
         'F2FS'  'Flash-Friendly-FS for SSD or NVMe')
-  single_choice_if_empty  FS 'Select filesystem to use' TMP1 || return $?
+  single_choice_if_empty  FS 'Select filesystem to use' TMP1
 
   if [ "${FS}" = 'BTRFS' ]; then
     TMP1=('root_only'  'Just one subvolume for "/".' \
           '@root@home' 'Two subvolumes @ and @home. This configuration allows usage of "Timeshift".')
-    single_choice_if_empty  FS_BTRFS_SUBVOL_LAYOUT 'Select your preferred subvolume layout' TMP1 || return $?
+    single_choice_if_empty  FS_BTRFS_SUBVOL_LAYOUT 'Select your preferred subvolume layout' TMP1
   fi
 
-  ask_user_if_empty HOSTNAME 'Enter hostname:' || return $?
-  ask_user_if_empty USERNAME 'Enter username:' || return $?
+  ask_user_if_empty HOSTNAME 'Enter hostname:'
+  ask_user_if_empty USERNAME 'Enter username:'
 
   if [ -z "${USER_PWD}" ]; then
-    ask_user_if_empty USER_PWD 'Enter a user password:' || return $?
-    ask_user_if_empty USER_PWD2 'Please enter the password again:' || return $?
+    ask_user_if_empty USER_PWD 'Enter a user password:'
+    ask_user_if_empty USER_PWD2 'Please enter the password again:'
     # shellcheck disable=SC2153
     [[ "${USER_PWD}" == "${USER_PWD2}" ]] || {
-      echo 'Passwords did not match';
-      exit 1;
+      echo 'Passwords did not match'
+      exit 1
     }
   fi
 
   TMP1=('true' 'Yes' 'false' 'No')
-  single_choice_if_empty  FDE 'Shall Full-Disk-Encryption be enabled?' TMP1 || return $?
+  single_choice_if_empty  FDE 'Shall Full-Disk-Encryption be enabled?' TMP1
 
   if [ "${FDE}" = 'true' ] && [ -z "${LUKS_PWD}" ]; then
-    ask_user_if_empty LUKS_PWD 'Enter a disk encryption password:' || return $?
-    ask_user_if_empty LUKS_PWD2 'Please enter the password again:' || return $?
+    ask_user_if_empty LUKS_PWD 'Enter a disk encryption password:'
+    ask_user_if_empty LUKS_PWD2 'Please enter the password again:'
     # shellcheck disable=SC2153
     [[ "${LUKS_PWD}" == "${LUKS_PWD2}" ]] || {
-      echo 'Passwords did not match';
-      exit 1;
+      echo 'Passwords did not match'
+      exit 1
     }
   fi
 }
@@ -233,7 +235,7 @@ function get_additional_mount_options() {
 		;;
   esac
 
-  multi_choice_if_empty  FS_ADDITIONAL_MOUNT_OPTIONS 'Select mount options' TMP1 || return $?
+  multi_choice_if_empty  FS_ADDITIONAL_MOUNT_OPTIONS 'Select mount options' TMP1
 }
 
 function mount_partitions() {
@@ -245,26 +247,26 @@ function mount_partitions() {
       'root_only')
         # Nothing special; same steps as for a regular FS
         echo 'Mounting data partition with options: '"${FS_MOUNT_OPTIONS}"
-        sudo mount -o "${FS_MOUNT_OPTIONS}" "${DATA_PART}" /mnt || return $?
+        sudo mount -o "${FS_MOUNT_OPTIONS}" "${DATA_PART}" /mnt
         ;;
       '@root@home')
         # Timeshift BTRFS subvol layout:
         # https://github.com/teejee2008/timeshift#supported-system-configurations
 
         # Mount top level subvolume
-        sudo mount -o subvolid=5 "${DATA_PART}" /mnt || return $?
+        sudo mount -o subvolid=5 "${DATA_PART}" /mnt
         # Create subvolumes @ and @home
-        sudo btrfs subvolume create /mnt/@     || return $?
-        sudo btrfs subvolume create /mnt/@home || return $?
+        sudo btrfs subvolume create /mnt/@
+        sudo btrfs subvolume create /mnt/@home
         # List the created subvolumes
-        sudo btrfs subvolume list /mnt || return $?
+        sudo btrfs subvolume list /mnt
         # Umount the top level subvolume
-        sudo umount -R /mnt || return $?
+        sudo umount -R /mnt
 
         echo 'Mounting @ and @home subvolumes with options: '"${FS_MOUNT_OPTIONS}"
-        sudo mount -o 'subvol=@,'"${FS_MOUNT_OPTIONS}"     "${DATA_PART}" /mnt      || return $?
-        sudo mkdir /mnt/home || return $?
-        sudo mount -o 'subvol=@home,'"${FS_MOUNT_OPTIONS}" "${DATA_PART}" /mnt/home || return $?
+        sudo mount -o 'subvol=@,'"${FS_MOUNT_OPTIONS}"     "${DATA_PART}" /mnt
+        sudo mkdir /mnt/home
+        sudo mount -o 'subvol=@home,'"${FS_MOUNT_OPTIONS}" "${DATA_PART}" /mnt/home
         ;;
       *)
         echo 'BTRFS subvolume layout '"${FS_BTRFS_SUBVOL_LAYOUT}"' not supported!'
@@ -273,12 +275,12 @@ function mount_partitions() {
       esac
   else
     echo 'Mounting data partition with options: '"${FS_MOUNT_OPTIONS}"
-    sudo mount -o "${FS_MOUNT_OPTIONS}" "${DATA_PART}" /mnt || return $?
+    sudo mount -o "${FS_MOUNT_OPTIONS}" "${DATA_PART}" /mnt
   fi
 
   echo 'Mounting boot partition ...'
-  sudo mkdir /mnt/boot                || return $?
-  sudo mount "${BOOT_PART}" /mnt/boot || return $?
+  sudo mkdir /mnt/boot
+  sudo mount "${BOOT_PART}" /mnt/boot
 }
 
 function run_pacstrap() {
@@ -328,7 +330,7 @@ function run_pacstrap() {
   fi
   args+=('/mnt')
 
-  sudo pacstrap "${args[@]}" "${PKGS[@]}" || return $?
+  sudo pacstrap "${args[@]}" "${PKGS[@]}"
 }
 
 function run_genfstab() {
@@ -342,7 +344,7 @@ function run_genfstab() {
   case "${FS}" in
 	BTRFS)
 	  # Remove "subvolid=..." mount option but leave "subvol=..." mount option
-	  fstab=$(printf '%s' "${fstab}" | sed 's/,subvolid=[^,\s]\+//') || return $?
+	  fstab=$(printf '%s' "${fstab}" | sed 's/,subvolid=[^,\s]\+//')
 	  # Check if fstab does still contain subvolid mount option
     if printf '%s' "${fstab}" | grep -q 'subvolid='; then
 	    echo 'This should not happen!'
@@ -361,7 +363,7 @@ function run_genfstab() {
 		;;
   esac
 
-  printf '%s' "${fstab}" | sudo tee /mnt/etc/fstab >/dev/null || return $?
+  printf '%s' "${fstab}" | sudo tee /mnt/etc/fstab >/dev/null
 }
 
 function config_hostname_and_hosts() {
@@ -372,7 +374,7 @@ function config_hostname_and_hosts() {
   #   IPV6_CAPABLE: optional, 'true'
 
   echo 'Set hostname ...'
-  echo "${HOSTNAME}" | sudo tee /mnt/etc/hostname >/dev/null || return $?
+  echo "${HOSTNAME}" | sudo tee /mnt/etc/hostname >/dev/null
 
   echo 'Create hosts file ...'
   # If the system has a permanent IP address, it should be used instead of 127.0.1.1.
@@ -389,14 +391,14 @@ function config_hostname_and_hosts() {
   echo '# The following lines are desirable for IPv4 capable hosts
 127.0.0.1     localhost
 # 127.0.1.1 is often used for the FQDN of the machine
-'"${STATIC_IP}  ${FQDN}  ${HOSTNAME}" | sudo tee /mnt/etc/hosts >/dev/null || return $?
+'"${STATIC_IP}  ${FQDN}  ${HOSTNAME}" | sudo tee /mnt/etc/hosts >/dev/null
 
   if [ "${IPV6_CAPABLE}" = 'true' ]; then
     echo '
 # The following lines are desirable for IPv6 capable hosts
 ::1           localhost ip6-localhost ip6-loopback
 ff02::1       ip6-allnodes
-ff02::2       ip6-allrouters' | sudo tee -a /mnt/etc/hosts >/dev/null || return $?
+ff02::2       ip6-allrouters' | sudo tee -a /mnt/etc/hosts >/dev/null
   fi
 }
 
@@ -409,14 +411,14 @@ function user_and_pwd() {
   echo 'Adding user and changing shell to /bin/zsh ...'
   # -m: create home
   # -U: Create a group with the same name as the user, and add the user to this group.
-  sudo arch-chroot /mnt useradd -m -s /usr/bin/zsh -g wheel "${USERNAME}" || return $?
-  sudo arch-chroot /mnt chsh       -s /usr/bin/zsh                        || return $?
+  sudo arch-chroot /mnt useradd -m -s /usr/bin/zsh -g wheel "${USERNAME}"
+  sudo arch-chroot /mnt chsh       -s /usr/bin/zsh
 
   # If ROOT_PWD is not given, the use USER_PWD for root user
   ROOT_PWD="${ROOT_PWD:="${USER_PWD}"}"
 
-  printf '%s:%s' "${USERNAME}" "${USER_PWD}" | sudo chpasswd --root /mnt || return $?
-  printf '%s:%s' "root"        "${ROOT_PWD}" | sudo chpasswd --root /mnt || return $?
+  printf '%s:%s' "${USERNAME}" "${USER_PWD}" | sudo chpasswd --root /mnt
+  printf '%s:%s' "root"        "${ROOT_PWD}" | sudo chpasswd --root /mnt
 }
 
 function bootloader() {
@@ -431,10 +433,10 @@ function bootloader() {
     # portable fallback efi name for grub:
     # * https://www.rodsbooks.com/efi-bootloaders/installation.html#alternative-naming
     # * arch-chroot /mnt cp /boot/EFI/GRUB/grubx64.efi /boot/EFI/BOOT/bootx64.efi
-    sudo arch-chroot /mnt grub-install --target=x86_64-efi --bootloader-id=GRUB --efi-directory=/boot --removable || return $?
+    sudo arch-chroot /mnt grub-install --target=x86_64-efi --bootloader-id=GRUB --efi-directory=/boot --removable
     ;;
   bios)
-    sudo arch-chroot /mnt grub-install --target=i386-pc "${TARGET_BLOCK_DEVICE}" || return $?
+    sudo arch-chroot /mnt grub-install --target=i386-pc "${TARGET_BLOCK_DEVICE}"
     ;;
   *)
     echo 'Not yet implemented!'
@@ -455,14 +457,14 @@ function bootloader() {
         # Use filename .../20- for the holoscript so that it gets executed after the one from de-p1st-grub
         local holoScriptDir=/mnt/usr/share/holo/files/20-de-p1st-installer/etc/default/
         # The holoscript shall contain one 'sed "..."' command
-        sudo mkdir -p "${holoScriptDir}" || return $?
+        sudo mkdir -p "${holoScriptDir}"
         sudo echo '#!/bin/sh
 sed "s|^GRUB_CMDLINE_LINUX=\"\"\$|GRUB_CMDLINE_LINUX=\"cryptdevice=/dev/disk/by-uuid/'"${LUKS_PART_UUID}"':crypt\"|"' \
-          | sudo tee "${holoScriptDir}"/grub.holoscript || return $?
-        sudo chmod 0544 "${holoScriptDir}"/grub.holoscript || return $?
+          | sudo tee "${holoScriptDir}"/grub.holoscript
+        sudo chmod 0544 "${holoScriptDir}"/grub.holoscript
       }
       # Then we apply the holoscript
-      sudo arch-chroot /mnt holo apply --force file:/etc/default/grub || return $?
+      sudo arch-chroot /mnt holo apply --force file:/etc/default/grub
       ;;
     false)
       true
@@ -474,7 +476,7 @@ sed "s|^GRUB_CMDLINE_LINUX=\"\"\$|GRUB_CMDLINE_LINUX=\"cryptdevice=/dev/disk/by-
     esac
 
     # And finally run grub-mkconfig
-    sudo arch-chroot /mnt grub-mkconfig -o /boot/grub/grub.cfg || return $?
+    sudo arch-chroot /mnt grub-mkconfig -o /boot/grub/grub.cfg
   }
 }