gistfile1.txt

class Process
  def initialize(pid)
    @pid = pid.to_i
  end
  
  # Return true if this process is running, false otherwise
  def exists?
    system("kill -0 #{@pid} &> /dev/null")
  end
  
  # Memory usage in kilobytes (resident set size)
  def memory
    ps_int('rss')
  end
  
  # Percentage memory usage
  def percent_memory
    ps_float('%mem')
  end
  
  # Percentage CPU usage
  def percent_cpu
    ps_float('%cpu')
  end
  
  # Seconds of CPU time (accumulated cpu time, user + system)
  def cpu_time
    time_string_to_seconds(ps_string('time'))
  end
  
  private  
    def ps_int(keyword)
      `ps -o #{keyword}= -p #{@pid}`.to_i
    end
  
    def ps_float(keyword)
      `ps -o #{keyword}= -p #{@pid}`.to_f
    end
  
    def ps_string(keyword)
      `ps -o #{keyword}= -p #{@pid}`.strip
    end
  
    def time_string_to_seconds(text)
      _, minutes, seconds, useconds = *text.match(/(\d+):(\d{2}).(\d{2})/)
      (minutes.to_i * 60) + seconds.to_i
    end
end

def every(seconds)
  while true
    yield
    sleep seconds
  end
end

every 5 do
  `ps -ax -o %p%c | grep apache2`.each do |line|
    line.match(/(\d+)/)
    p = Process.new($1)
    puts p.percent_cpu
  end
end