Script to be used as a munki preinstall_script which will only succeed and subsequently install software if the Mac's macOS version matches one in the SUPPORTED_VERS list

munki_preinstall_script_compareVersions.bash

#!/bin/bash

# Method inspired by:
# https://stackoverflow.com/questions/12768265/bash-compare-a-string-vs-a-list-of-strings

# Usage:
#
# While munki provides minimum_os_version and maximum_os_version to define a supported
# OS version range, some software define individual macOS versions as officially
# supported. In these cases, defining a supported range is helpful, but ultimately
# insufficient.
#
# Adding this script as a munki 'preinstall_script' and defining supported versions
# in the SUPPORTED_VERS variable (separated by spaces) will either match (exit 0) causing
# the software to be installed or not match (exit 1) and not install the software.

# Admin-provided supported version list, separated by spaces
SUPPORTED_VERS=( 10.13.6 10.14.6 10.15.3 10.15.5 )

# Get a Mac's installed OS product version (ex. 10.14.6)
OSVERS=$(/usr/bin/sw_vers -productVersion)
# Set blank value
SUPPORTED=""
# Populate list with supported versions
VERS_LIST=$(/usr/bin/printf '%s\n' "${SUPPORTED_VERS[@]}")

# Compare installed OS version to supported version list, break loop if match found
for v in $VERS_LIST; do
	if [[ "$v" = "$OSVERS" ]]; then
		SUPPORTED="yes"
		break
	fi
done

# Verify result & exit 0 if matched and install software, exit 1 if not matched
# and don't install
if [ "$SUPPORTED" = "yes" ]; then
	/bin/echo "VERIFIED: macOS version ${OSVERS} is listed in the supported OS list."
  	/bin/echo "Proceeding with install ..."
	exit 0
else
	/bin/echo "FAILED: macOS version ${OSVERS} is not in the supported OS list."
  	/bin/echo "Cancelling install ..."
	exit 1
fi