#!/bin/sh -e
for line in $(systemctl show -p SystemState,NFailedUnits); do
	split_idx="$(printf "%s" "$line" | awk '{print index($0, "=")}')"
	property="$(printf "%s" "$line" | awk '{print substr($0, 1, '"$split_idx"' - 1)}')"
	value="$(printf "%s" "$line" | awk '{print substr($0, '"$split_idx"' + 1)}')"

	case "$property" in
		"SystemState")
			SYSTEM_STATE="$value"
			;;
		"NFailedUnits")
			FAILED_UNITS="$value"
			;;
		*)
			;;
	esac
done

if [ -z "$SYSTEM_STATE" ] || [ -z "$FAILED_UNITS" ]; then
	echo "$0: failed to get expected data from system." >&2
	exit 3
fi

printf "SYSTEM %s: %d units failed.\n" "$SYSTEM_STATE" "$FAILED_UNITS"

if [ "0" = "$FAILED_UNITS" ]; then
	exit 0
else
	printf "\nFailed units:\n"
	systemctl list-units --failed --no-legend | awk '{print "- " $1;}'
	exit 2
fi