macos_prepare_distro.sh

#!/usr/bin/env bash
set -x

## Get available distros
# softwareupdate --list-full-installers
# softwareupdate --fetch-full-installer --full-installer-version 13.0.1

# Default size ~16 GB
DISK_SIZE="15361m"
STORAGE="/Users/${USER}/Downloads/macos_distro"
VERSION="Monterey"  # Monterey, Version: 12.7.6, Size: 12118346KiB, Build: 21H1320
#VERSION="Ventura"  # Ventura, Version: 13.7, Size: 11922748KiB, Build: 22H123
#VERSION="Sonoma"   # Sonoma, Version: 14.7, Size: 13343514KiB, Build: 23H124


# Create storage target
mkdir -p "${STORAGE}"
ls -la "${STORAGE}"

## Check downloaded distros
APP="Install macOS ${VERSION}.app"
echo "Locating installer .."
if ! ls -la /Applications/ | grep -q "$APP"; then
    echo "Installer not found: $APP"
    exit 1
fi
echo "- found installer '$APP'"

## Create ISO from installer
echo "Creating blank image .."
hdiutil create -o "${STORAGE}/${VERSION}.cdr" -size $DISK_SIZE -layout SPUD -fs HFS+J
echo "Attaching blank image .."
hdiutil attach "${STORAGE}/${VERSION}.cdr.dmg" -noverify -mountpoint /Volumes/install_build
echo "Creating installation media .."
sudo "/Applications/${APP}/Contents/Resources/createinstallmedia" --volume /Volumes/install_build --nointeraction
echo "detaching volumes .."
hdiutil detach "/Volumes/Shared Support"
hdiutil detach "/Volumes/Install macOS ${VERSION}"
echo "converting from DMG to ISO .."
hdiutil convert "${STORAGE}/${VERSION}.cdr.dmg" -format UDTO -o "${STORAGE}/${VERSION}.iso"
mv "${STORAGE}/${VERSION}.iso.cdr" "${STORAGE}/${VERSION}.iso"
echo "removing temporary files .."
rm "${STORAGE}/${VERSION}.cdr.dmg"

echo "done."

# References
# - https://support.apple.com/en-us/101578
# - https://gist.github.com/julianxhokaxhiu/42332e67640daad8f18386eeec43ea73