countdown/countdown.sh

#!/bin/bash

# Copyright (C) 2022 Ortega Froysa, Nicolás <nicolas@ortegas.org> All rights reserved.
# Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
#
# This software is provided 'as-is', without any express or implied
# warranty. In no event will the authors be held liable for any damages
# arising from the use of this software.
#
# Permission is granted to anyone to use this software for any purpose,
# including commercial applications, and to alter it and redistribute it
# freely, subject to the following restrictions:
#
# 1. The origin of this software must not be misrepresented; you must not
#    claim that you wrote the original software. If you use this software
#    in a product, an acknowledgment in the product documentation would be
#    appreciated but is not required.
#
# 2. Altered source versions must be plainly marked as such, and must not be
#    misrepresented as being the original software.
#
# 3. This notice may not be removed or altered from any source
#    distribution.

set -euo pipefail

if [ $# -gt 1 ]
then
	echo "Too many arguments"
	echo "Usage: $0 [COUNT]"
	exit 1
elif [ $# -eq 1 ] && [ "$1" = "-h" ]
then
	echo "Usage: $0 [COUNT]"
	exit 0
elif [ $# -eq 1 ] && [ "$1" -le 0 ]
then
	echo "COUNT must be a positive integer"
	exit 1
fi

COUNT=${1:-5}

for i in $(seq "$COUNT" -1 1)
do
	echo "$i"
	sleep 1
done

echo 0