Need to check some host's availability by arping, but have no time to look up which network intrface you need? aarping.sh is here to help you.

aarping.sh

#!/bin/sh

if [ -z "${1}" ]; then
        echo "Chocho?" >&2
        exit 1
fi

HOSTIP="${@: -1}"

ROUTE=$(ip route get "${HOSTIP}")
        if [ -z "${ROUTE}" ]; then
        echo "Can't find the route to this host" >&2
        exit 1
fi

IFACE=$(echo "${ROUTE}" | sed -rn "s/^.*dev (eth.[0-9\.]+)[[:space:]]+.*$/\1/gp")
        if [ -z "${IFACE}" ]; then
        echo "Can't find the interface of this host" >&2
        exit 1
fi

exec arping -I "${IFACE}" ${@}