Simple countdown script

countdown

#!/bin/bash

# Count down for a specified time
# Example (count down for 3 minutes and 30 seconds):
#   $ countdown 3m 30s

shopt -s extglob

time=0

while [ -n "$1" ]; do
    case $1 in
        +([0-9]))
            parsed=$1
            ;;
        +([0-9])s)
            parsed=${1%s}
            ;;
        +([0-9])m)
            raw=${1%m}
            parsed=$((raw * 60))
            ;;
        +([0-9])h)
            raw=${1%h}
            parsed=$((raw * 3600))
            ;;
        +([0-9])d)
            raw=${1%d}
            parsed=$((raw * 86400))
            ;;
        *)
            echo >&2 "Invalid: '$1'"
            exit
            ;;
    esac
    time=$((time + parsed))
    shift
done

trap 'tput cnorm' EXIT
tput civis

digits=$(echo "scale=0; l($time)/l(10) + 1" | bc -l)

while [ "$time" -gt 0 ]; do
    time=$((time - 1))
    printf "\r%${digits}d" $time
    sleep 1
done

date=$(date +%T)

printf "\r%s: Time is up\n" "$date"
notify-send --expire-time=0 'countdown' "$date: time is up"