TapTempo.bash

#!/bin/bash
# SPDX-License-Identifier: WTFPL
# Copyright © 2018 Neil "Superna" Armstrong
# This work is free. You can redistribute it and/or modify it under the
# terms of the Do What The Fuck You Want To Public License, Version 2,
# as published by Sam Hocevar. See the COPYING file or http://www.wtfpl.net/ 
# for more details.

PREV="$(date +%s%N | cut -b1-13)"
TAPS="0"
COUNT="0"

while read -p "tapTempo : press any key (CTRL+D for quit)" tap ; do
	CUR="$(date +%s%N | cut -b1-13)"
	TAPS="$TAPS + $(($CUR-$PREV))"
	PREV=$CUR
	COUNT="$(($COUNT + 1))"
done

echo ""
echo BPM : $((60000 / $(($(($TAPS + 0)) / $COUNT))))