Net interfaces throughput top written in bash

ntop.sh

#!/usr/bin/env bash

INTERVAL=5
NETPATH="/sys/class/net"
RX1_ARR=()
TX1_ARR=()
RX2_ARR=()
TX2_ARR=()

while true; do
    NAME_ARR=()
    for interface in $NETPATH/*; do
        interface=$(echo $interface | rev | cut -d/ -f1 | rev)
        NAME_ARR+=($interface)
    done
    
    RX_TOTAL=0
    TX_TOTAL=0
    clear && printf "\e[7m%-16s\t%-9s\t%-9s\n\e[0m" "Iface Name" "RX Kbps" "TX Kbps"
    for i in "${!NAME_ARR[@]}"; do
        RX2_ARR[$i]=${RX1_ARR[$i]}
        TX2_ARR[$i]=${TX1_ARR[$i]}
        RX1_ARR[$i]=`cat $NETPATH/${NAME_ARR[$i]}/statistics/rx_bytes`
        TX1_ARR[$i]=`cat $NETPATH/${NAME_ARR[$i]}/statistics/tx_bytes`
        
        RX_KBPS=$[(${RX2_ARR[$i]} - ${RX1_ARR[$i]}) / -1024 / $INTERVAL]
        TX_KBPS=$[(${TX2_ARR[$i]} - ${TX1_ARR[$i]}) / -1024 / $INTERVAL]
        
        TX_TOTAL=$[$TX_TOTAL + $TX_KBPS]
        RX_TOTAL=$[$RX_TOTAL + $RX_KBPS]
        if [ "$RX_KBPS" != "0" ] || [ "$TX_KBPS" != "0" ]; then
            printf "%-16s\t%9d\t%9d\n" "${NAME_ARR[$i]}" "$RX_KBPS" "$TX_KBPS"
        fi
    done
    
    printf "\n\e[7mTOTAL\tRX: %9d\tTX: %9d\e[0m" "$RX_TOTAL" "$TX_TOTAL"
    sleep "$((INTERVAL))s"
done