move script installation into a separate file

install.sh

@@ -0,0 +1,89 @@
+#!/bin/bash
+
+function main {
+
+  # declare local variables
+  local OPTIONS_PARSED
+
+  # set default values and configuration
+  SELF_PATH="$(readlink -f "$0")"
+  SELF_NAME="$(basename "$SELF_PATH")"
+  WITH_DESKTOP_HELPERS=false
+
+  # parse arguments
+  OPTIONS_PARSED=$(
+    getopt \
+      --options 'd' \
+      --longoptions 'with-desktop-helpers' \
+      --name "$SELF_NAME" \
+      -- "$@"
+  )
+
+  # replace arguments
+  eval set -- "$OPTIONS_PARSED"
+
+  # apply arguments
+  while [[ $# -gt 0 ]]; do
+    case "$1" in
+    -d | --with-desktop-helpers)
+      WITH_DESKTOP_HELPERS=true
+      shift 1
+      ;;
+    --)
+      shift 1
+      break
+      ;;
+    *)
+      break
+      ;;
+    esac
+  done
+
+  # check if there is no unassigned argument left
+  if [[ $# -ne 0 ]]; then
+    echo "$SELF_NAME: cannot handle unassigned arguments: $*" >&2
+    exit 1
+  fi
+
+  task_install_script
+}
+
+function verify_root_privileges {
+
+  if [[ $EUID -ne 0 ]]; then
+    echo "$SELF_NAME: require root privileges" >&2
+    exit 1
+  fi
+}
+
+function task_install_script {
+
+  # declare local variables
+  local TEMPDIR
+  local SBINDIR
+  local ENTRY
+
+  # verify preconditions
+  verify_root_privileges
+
+  TEMPDIR="$(mktemp -d)"
+  SBINDIR='/usr/local/sbin'
+
+  git clone 'https://github.com/brettaufheber/ubuntu-headless-installer.git' "$TEMPDIR"
+
+  cp -v "$TEMPDIR/ubuntu-installer.sh" "$SBINDIR"
+  chmod a+x "$SBINDIR/ubuntu-installer.sh"
+
+  if "$WITH_DESKTOP_HELPERS"; then
+    for ENTRY in "$TEMPDIR/desktop-helpers"/*; do
+      cp -v "$ENTRY" "$SBINDIR"
+      chmod a+x "$SBINDIR/$(basename "$ENTRY")"
+    done
+  fi
+
+  rm -rf "$TEMPDIR"
+}
+
+set -euo pipefail
+main "$@"
+exit 0

ubuntu-installer.sh

@@ -158,12 +158,6 @@ function main {
 
     # select task
     case "$TASK" in
-      install-script)
-        task_install_script
-        ;;
-      install-desktop-helpers)
-        task_install_desktop_helpers
-        ;;
       update)
         task_update
         ;;
@@ -386,52 +380,6 @@ function verify_mounting_boot {
   fi
 }
 
-function task_install_script {
-
-  # declare local variables
-  local TEMPDIR
-  local BINDIR
-
-  # verify preconditions
-  verify_root_privileges
-
-  TEMPDIR="$(mktemp -d)"
-  BINDIR='/usr/local/sbin'
-
-  git clone 'https://github.com/brettaufheber/ubuntu-headless-installer.git' "$TEMPDIR"
-
-  cp -v "$TEMPDIR/ubuntu-installer.sh" "$BINDIR"
-  chmod a+x "$BINDIR/ubuntu-installer.sh"
-
-  rm -rf "$TEMPDIR"
-}
-
-function task_install_desktop_helpers {
-
-  # declare local variables
-  local TEMPDIR
-  local BINDIR
-
-  # verify preconditions
-  verify_root_privileges
-
-  TEMPDIR="$(mktemp -d)"
-  BINDIR='/usr/local/sbin'
-
-  git clone 'https://github.com/brettaufheber/ubuntu-headless-installer.git' "$TEMPDIR"
-
-  for i in "$TEMPDIR/desktop-helpers"/*; do
-
-    f="$(basename "$i")"
-
-    cp -v "$i" "$BINDIR"
-    chmod a+x "$BINDIR/$f"
-
-  done
-
-  rm -rf "$TEMPDIR"
-}
-
 function task_update {
 
   # verify preconditions
@@ -452,9 +400,6 @@ function task_update {
     # update via Flatpak package manager
     flatpak -y update
 
-    # update helper scripts
-    ubuntu-installer.sh install-desktop-helpers
-
   fi
 }
 
@@ -1501,9 +1446,6 @@ function configure_desktop {
     # add flatpak remote: flathub
     chroot "$CHROOT" flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
 
-    # install helper scripts
-    chroot "$CHROOT" "$SELF_NAME" install-desktop-helpers
-
     # modify default GNOME settings
     install_default_gnome_settings