#! /bin/sh

if [[ $# -ne 1 ]]
then
	echo "USAGE: timer <number>"
	exit 10
fi

if [[ $1 =~ 'help' ]]
then
	echo "Timer : timer <n sec>"
	exit 0
fi

if [[ $1 -le 0 ]]
then
	echo "The argument must be greater than 0"
	exit 11
fi

for ((i=$1;i>=0;i--))
do
	sleep 1
	clear
	echo $i
done

read
clear

exit 0