reverse_mouse_scroll_direction.sh

#!/bin/bash
# reverse mouse scroll direction

function _reverse_mouse_scroll_direction() {
	local IFS=$'\n'

	local DEVICE_NAME=$1
	local PROP_NAME=$2

	for id in $(xinput list | grep -F "${DEVICE_NAME}" | perl -n -e'/id=(\d+)/ && print $1')
	do
		for prop in $(xinput list-props "$id" | grep -F "${PROP_NAME}" | perl -n -e'/:\s*(-?\d+)\s*,\s*(-?\d+)\s*$/ && print -$1, " ", -$2')
		do
			eval "xinput set-prop ${id} \"${PROP_NAME}\" $prop"
		done
	done
}

_reverse_mouse_scroll_direction "Synaptics TouchPad" "Synaptics Scrolling Distance"