#!/bin/sh
set -eu

usage() {
	cat <<-'EOF'
		Usage:
		  check
		  check -h
	EOF
}

help() {
	cat <<-'EOF'


		Options:
		  -h, --help    show this message


		Run system sanity checks, such as email reachability, alarms
		reachability, etc.


		Examples:

		  Just run it

		    $ check
	EOF
}


for flag in "$@"; do
	case "$flag" in
		--)
			break
			;;
		--help)
			usage
			help
			exit
			;;
		*)
			;;
	esac
done

while getopts 'h' flag; do
	case "$flag" in
		h)
			usage
			help
			exit
			;;
		*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))


if [ "$(id -un)" != 'root' ]; then
	printf 'This script must be run as root.\n\n' >&2
	usage >&2
	exit 2
fi


uuid() {
	od -xN20 /dev/urandom |
		head -n1 |
		awk '{OFS="-"; print $2$3,$4,$5,$6,$7$8$9}'
}

for alias in abuse admin postmaster hostmaster; do
	uuid | mail -s "\"$alias\" alias test from $(id -un)@$(hostname)" "$alias@$(hostname)"
done