adb logcat with color and filter by package/process name

lolcat.rb

#!/usr/bin/env ruby
require 'colorize'
require 'optparse'

class LOLCat
  def initialize options = {}
    @tagspecs = options[:tagspecs] || []
    @whitelist = options[:processes] || []
    @processes = Hash.new
  end

  def level_color level
    case level
    when 'V'
      { color: :default, background: :default }
    when 'D'
      { color: :blue, background: :light_black }
    when 'I'
      { color: :green, background: :light_black }
    when 'W'
      { color: :black, background: :yellow }
    when 'E'
      { color: :white, background: :red }
    else
      { color: :default }
    end
  end

  def fetch_processes
    puts '>>> fetching processes'.light_blue
    IO.popen('adb shell ps').each do |line|
      # Line format:
      # USER     PID   PPID  VSIZE  RSS     WCHAN    PC         NAME
      # app_5     228   32    83520  20552 ffffffff afd0c51c S com.android.music

      match = line.match /(?'user'\S+)\s+(?'pid'\d+)\s+\d+\s+\d+\s+\d+\s+\S+\s+\S+\s+\S\s(?'name'\S+)/
      @processes[match[:pid]] = { user: match[:user], name: match[:name] } if match
    end
  end

  def print_processes
    fetch_processes
    @processes.each { |pid, info| puts "%6{pid} %10{user} %{name}" % info.merge(pid: pid) }
  end

  def rainbow
    IO.popen(%w[adb lolcat] + @tagspecs).each do |line|
      # Line format:
      # level/tag( pid): msg
      # I/ARMAssembler(   60): generated scanline__00000077:03515104_00001004_00000000 [ 65 ipp] (85 ins) at [0x445ed6e0:0x445ed834] in 863000 ns

      match = line.match /(?'level'.)\/(?'tag'[^(]*)\(\s*(?'pid'\d+)\): (?'message'.*)/
      if match
        fetch_processes unless @processes.keys.include?(match[:pid])

        process = @processes[match[:pid]]
        if process
          next unless @whitelist.empty? || @whitelist.include?(process[:name])
        else
          # Old process is no longer on list.  Don't wanna fetch for this guy again.
          @processes[match[:pid]] = false
        end

        head = "%5d|%-20s" % [match[:pid], match[:tag][0,20]]
        puts head.to_s.colorize(level_color match[:level]) << ' ' << match[:message]
      else
        puts line.chomp
      end
    end
  end
end

options = {}

optparse = OptionParser.new do |opts|
  # Set a banner, displayed at the top
  # of the help screen.
  opts.banner = "Usage: lolcat [options] tagspec1 tagspec2  ..."

  # Define the options, and what they do
  options[:list_processes] = false
  opts.on( '-l', '--list-processes', 'List processes and exit' ) do
    options[:list_processes] = true
  end

  # Define the options, and what they do
  options[:processes] = []
  opts.on( '-p', '--process NAME', 'Show only this process. Can use multiple times.' ) do |name|
    options[:processes] << name
  end

  # This displays the help screen, all programs are
  # assumed to have this option.
  opts.on( '-h', '--help', 'Display this screen' ) do
    puts opts
    exit
  end
end

optparse.parse!
options[:tagspecs] = ARGV.dup

lolcat = LOLCat.new options

if options[:list_processes]
  lolcat.print_processes
else
  lolcat.rainbow
end

how to use this script?