Изменение скрипта Bash

#!/bin/bash
PREFIX="${1:-NOT_SET}"
INTERFACE="$2"

[[ "$PREFIX" = "NOT_SET" ]] && { echo "\$PREFIX must be passed as first positional argument"; exit 1; }
if [[ -z "$INTERFACE" ]]; then
    echo "\$INTERFACE must be passed as second positional argument"
    exit 1
fi

for SUBNET in {1..255}
do
    for HOST in {1..255}
    do
        echo "[*] IP : ${PREFIX}.${SUBNET}.${HOST}"
        arping -c 3 -i "$INTERFACE" "${PREFIX}.${SUBNET}.${HOST}" 2> /dev/null
    done
done