Create ISO of "Install macOS Sequoia"

create_macos_iso.sh

#!/bin/bash
# based on https://osxdaily.com/2020/07/20/how-convert-macos-installer-iso/, but compressed to the details

MACOSNAME="Sequoia"
IMAGESIZE=17000m

set -e

TMPDIR=""
trap cleanup EXIT

function main() {
  echo "Ensure installer for '$MACOSNAME' is already downloaded, at /Applications/Install macOS ${MACOSNAME}.app"
  read -p "Press enter to continue"

  TMPDIR=$(mktemp -d)
  echo "Creating empty destination image file..."
  hdiutil create "${TMPDIR}/${MACOSNAME}" -size "${IMAGESIZE}" -volname "${MACOSNAME}" -layout SPUD -fs HFS+J
  echo "Mounting volume..."
  hdiutil attach "${TMPDIR}/${MACOSNAME}.dmg" -noverify -mountpoint "/Volumes/${MACOSNAME}"

  echo "Burning media to volume..."
  pushd "/Applications/Install macOS ${MACOSNAME}.app/Contents/Resources"
  sudo ./createinstallmedia --volume "/Volumes/${MACOSNAME}" --nointeraction
  popd

  echo "Detaching volume again..."
  hdiutil detach "/Volumes/Install macOS ${MACOSNAME}"

  echo "Converting volume to ISO file..."
  hdiutil convert "${TMPDIR}/${MACOSNAME}.dmg" -format UDTO -o "${TMPDIR}/${MACOSNAME}.cdr"
  mv "${TMPDIR}/${MACOSNAME}.cdr" ~/Downloads/"macOS_${MACOSNAME}.iso"
  echo "File is available at ~/Downloads/macOS_${MACOSNAME}.iso"
  echo "You may want to delete the installer again: /Applications/Install macOS ${MACOSNAME}.app"
}

function cleanup() {
  echo "Cleanup any errored volumes..."
  hdiutil detach "/Volumes/${MACOSNAME}" || true
  hdiutil detach "/Volumes/Install macOS ${MACOSNAME}" || true
  echo "Cleanup up temp files..."
  if [ -n "$TMPDIR" ] && [ -d "$TMPDIR" ]; then
    rm -rf "$TMPDIR"
  fi
}

main