macos_upgrade.sh

# List all available installers
softwareupdate --list-full-installers
# In this case we are installing macOS Monterey 12.1
softwareupdate --fetch-full-installer --full-installer-version 12.1
installer_directory="/Applications/Install macOS Monterey.app"
# A + ↵ to accept the agreement
printf 'A\n' | sudo $installer_directory/Contents/Resources/startosinstall
# Validating that it was installed correctly
sw_vers