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

INLINE=0
COUNT=5

if [ $# -ge 1 ] && [ $# -le 2 ]
then
	for arg in "$@"
	do
		if [ "$arg" = "-i" ]
		then
			INLINE=1
		elif [ "$arg" = "-h" ] || [ "$arg" = "--help" ]
		then
			echo "Usage: $0 [-i] [COUNT]"
			echo "  COUNT: Number of seconds to count down from (default: 5)"
			echo "  -i: Inline mode (do not print each number on a new line)"
			exit 0
		elif [[ "$arg" =~ [0-9]+ ]]
		then
			COUNT="$arg"
		else
			echo "Unknown argument: $arg"
			exit 1
		fi
	done
fi

for i in $(seq "$COUNT" -1 1)
do
	if [ $INLINE -eq 0 ]
	then
		echo "$i"
	else
		printf "\r%s" "$i"
	fi
	sleep 1
done

if [ $INLINE -eq 0 ]
then
	echo "0"
else
	printf "\r%s\n" "0"
fi