ifbw(){(

  delay=5
  if='eth0'
  capture='/tmp/net-dev-eth0.txt'
  netdev='/proc/net/dev'

  curr_rx=
  curr_tx=
  last_rx=
  last_tx=

  capture(){

      cat $netdev | fgrep $if':' | cut -c8- | awk '{print $1 " " $9}' > $capture
      curr_rx=$( cut -d' ' -f1 /tmp/net-dev-eth0.txt )
      curr_tx=$( cut -d' ' -f1 /tmp/net-dev-eth0.txt )

      if [ "--show" = "$1" ]; then
	  clear 2>/dev/null

	  echo '['$( date '+%Y-%m-%d %H:%M:%S' )']' $if':' \
	      rx: $( echo 'scale=1;' '(' $curr_rx - $last_rx ')' '*' 8 / 1024 / $delay | bc -l ) Kbps \
	      tx: $( echo 'scale=1;' '(' $curr_tx - $last_tx ')' '*' 8 / 1024 / $delay | bc -l ) Kbps
      fi

      last_rx=$curr_rx
      last_tx=$curr_tx

  }

  capture
  sleep $delay
  capture --show
  while [ "--loop" = "$1" ] ; do
      sleep $delay
      capture --show
  done

)}