#!/usr/bin/env bash

[[ -z "${@}" ]] && { echo "No argument provided." >&2 ; exit 1; }

d=$(($(date +%s) + $1));
echo "Countdown started at $(date)"

while [[ "$d" -ge "$(date +%s)" ]]; do
	_dt=$((d - $(date +%s)))
	days=$((_dt / 86400))
	echo -ne "\r${days}d $(date -u --date @$((_dt)) +%H:%M:%S) ";
	sleep 0.1
done

echo -ne "\rCountdown finished $(date)\n"