#!/bin/sh
#
# Scripted by JoungKyun Kim
# 2001.2.15 http://www.oops.org
# This Script follows GPL2 License
#
# 2003. 1. 15 Modified to trap CTRL-c by kyong
# 2003. 1. 23 Added SECONDS arg, Kbps unit, minutes conversion and
# some cleanups by kyong
# 2010.05. 24 Modified Duration loop

IF="$1"
CHECK=/proc/net/dev
KMULTI=1024
#KMULTI=1000

start() {
    [ -f $CHECK ] || { echo "\"$CHECK\" does not exist." ; exit ; }
    fgrep -qs $IF: $CHECK || { echo "DEVICE \"$IF\" does not exist." ; exit ; }

    set `cat $CHECK | grep $IF: | cut -f2- -d:`
    IN0=$1
    OUT0=$9
}
stop() {
    local MSEC=$SECONDS

    set `cat $CHECK | grep $IF: | cut -f2- -d:`
    IN1=$1
    OUT1=$9
    let "IN = ($IN1 - $IN0) / ($MSEC * $KMULTI)"
    let "OUT = ($OUT1 - $OUT0) / ($MSEC * $KMULTI)"

    if [ $MSEC -lt 60 ] ;
    then
    MTIME="$MSEC second(s)"
    else
        let "MMIN = $MSEC / 60"
        let "MSEC = $MSEC - ($MMIN * 60)"
        MTIME="$MMIN minute(s) $MSEC second(s)"
        fi
        if [ $KMULTI -eq 1024 ] ;
        then
        KUNIT="KiB/s"
        elif [ $KMULTI -eq 1000 ] ;
        then
        KUNIT="KB/s"
        else
            KUNIT="?"
            fi

            #echo
            #echo "During $MTIME"
            echo "Inbound  : $IN $KUNIT (`let "IN=$IN*8"; echo $IN` Kbps)"
            echo "Outbound : $OUT $KUNIT (`let "OUT=$OUT*8"; echo $OUT` Kbps)"
            echo
}
usage() {
    echo "Usage : `basename "$0"` DEVICE [Duration Sec]"
    echo "Ex. : `basename "$0"` eth0"
    echo " `basename "$0"` eth0 10"
}

if [ $# = 0 -o $# -gt 2 ] ;
then
    usage ;
    exit
elif [ $# = 1 ] ;
then
    start ;
    trap 'stop;' SIGINT SIGQUIT
    echo "Ctrl-c to abort"
    sleep 365d
    exit 0
else
    while :
    do
        echo "$1 Interface [During $2 sec]"
        start ;
        unset SECONDS
        SECONDS=$2
        sleep $2
        stop ;
    done
fi