Streamline the installer for fresh Arch installs

install/steps/preflight.sh

@@ -0,0 +1,85 @@
+conflicting_network_services=(
+  systemd-networkd.service
+  iwd.service
+  dhcpcd.service
+  netctl.service
+)
+
+stop_install() {
+  printf 'ERROR %s\n' "$1" >&2
+  shift
+  local detail
+  for detail in "$@"; do
+    printf '      %s\n' "$detail" >&2
+  done
+  exit 1
+}
+
+require_regular_user() {
+  (( EUID != 0 )) && return 0
+  stop_install "run install.sh as your own user, not as root" \
+    "it installs into \$HOME and builds AUR packages, which makepkg refuses to do as root" \
+    "it asks for sudo when it needs it"
+}
+
+require_arch() {
+  command -v pacman &>/dev/null && return 0
+  stop_install "pacman not found; Blob installs on Arch Linux only"
+}
+
+require_sudo() {
+  [[ $check == true ]] && return 0
+  command -v sudo &>/dev/null || stop_install "sudo is not installed" \
+    "as root: pacman -S sudo, then add your user with visudo"
+  sudo -v || stop_install "sudo did not accept this user" \
+    "as root: add your user to the wheel group and allow it in visudo"
+}
+
+require_internet() {
+  [[ $check == true || $skip_packages == true ]] && return 0
+  curl -fsS --max-time 15 -o /dev/null https://archlinux.org && return 0
+  stop_install "no internet connection; packages cannot be downloaded" \
+    "connect first (iwctl for Wi-Fi), or rerun with --skip-packages"
+}
+
+report_network_conflicts() {
+  local unit
+  local -a enabled=()
+
+  for unit in "${conflicting_network_services[@]}"; do
+    [[ "$(system_unit_state "$unit")" == enabled ]] && enabled+=("$unit")
+  done
+
+  (( ${#enabled[@]} == 0 )) && return 0
+
+  warn "NetworkManager will be enabled, but so is: ${enabled[*]}"
+  say "      two network managers fight over the same interfaces after a reboot"
+  say "      once NetworkManager works: sudo systemctl disable ${enabled[*]}"
+}
+
+sudo_keepalive_pid=""
+
+start_sudo_keepalive() {
+  [[ $check == true ]] && return 0
+  while true; do
+    sudo -n true 2>/dev/null
+    sleep 60
+  done &
+  sudo_keepalive_pid=$!
+  trap stop_sudo_keepalive EXIT
+}
+
+stop_sudo_keepalive() {
+  [[ -n $sudo_keepalive_pid ]] && kill "$sudo_keepalive_pid" 2>/dev/null
+  sudo_keepalive_pid=""
+}
+
+run_preflight() {
+  require_regular_user
+  require_arch
+  require_sudo
+  require_internet
+  report_network_conflicts
+  start_sudo_keepalive
+  say "ok    preflight"
+}