Wraps the output of ```netstat -I en0 -b``` to keep an eye on your bandwith use.

ifwatch

#!/usr/bin/env ruby

#ln -s $PWD/ifwatch /usr/local/bin/

LIMITS = {
  red: 30*1024**2,
  yellow: 20*1024**2,
  green: 0
}

def humanize_bytes bytes, units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB']
  bytes < 1024 ? "#{sprintf('%9.2f', bytes)} #{units.first}" : humanize_bytes(bytes/1024.0, units[1..-1])
end

def colorize str, color
 color_code = {default: 0, red: 31, green: 32, yellow: 33, blue: 34, pink: 35, gray: 37}[color]
 "\e[#{color_code}m#{str}\e[0m"
end

begin
  while 1
    # retrieve current io use from netstat
    lines = `netstat -I en0 -b`.split("\n")
    fields = lines[1].split(' ').compact

    bytes = [Integer(fields[6]), Integer(fields[9])]
    bytes << bytes.inject(0) { |mem,val| mem + val }

    # get & save base for today
    filename ||= "#{File.expand_path(File.dirname(__FILE__))}/#{Time.now.strftime('%y%m%d_base')}"
    base_bytes ||= if File.exist?(filename)
      File.read(filename).split(';').map(&:to_i)
    else
      File.write(filename, bytes.map(&:to_s).join(';'))
      bytes
    end

    #clear screen
    print "\e[H\e[2J"

    %w(in out total).each_with_index do |s, i|
      current = bytes[i] - base_bytes[i]
      color = Array(LIMITS.find { |k,v| current > v }).first if s == 'total'
      color ||= :gray

      puts "#{s}:#{' '*(6-s.length)} #{colorize(humanize_bytes(current), color)}"
    end

    sleep(1)
  end
rescue SystemExit, Interrupt
  puts ""
end