Display loadavg and memory usage as a textual bar graph suitable for Tmux's statusbar: █▄▃ ▁█

uptime.rb

#!/usr/bin/ruby

module LinuxProcInfo
  def self.cpucount
    File.readlines("/proc/cpuinfo").find_all { |s| s.start_with?('processor') }.count
  end

  def self.loadavg
    File.read('/proc/loadavg').split[0, 3].collect(&:to_f)
  end

  def self.freemem
    fields = File.readlines('/proc/meminfo').inject(Hash.new) { |hash, line|
      field, value, unit = line.split(/:?\s+/)
      hash[field] = value
      hash
    }

    [ [ fields['MemTotal'].to_i, fields['MemFree'].to_i ], [ fields['SwapTotal'].to_i, fields['SwapFree'].to_i ] ]
  end
end

class Numeric
  def clamp(min, max)
    if self > max
      max
    elsif self < min
      min
    else
      self
    end
  end
end

class TerminalGraph
  def initialize
    @data = []
  end

  def <<(datum)
    datum = datum.to_f unless datum == nil
    @data << datum
    self
  end

  def delete_at(index)
    @data.delete_at(index)
    self
  end

  def render(min = nil, max = nil)
    max = @data.max { |d| d || 0.0 } unless max
    min = @data.min { |d| d || 0.0 } unless min
    height = max - min

    @data.inject("") { |s, datum|
      s + (datum.nil?? ' ' : single_bar((datum - min) / height))
    }
  end

  UNICODE_ZERO_BAR = 0x2581

  def single_bar(percentage)
    n = (7 * percentage.clamp(0.0, 1.0)).round
    (UNICODE_ZERO_BAR + n).chr(Encoding::UTF_8)
  end
end

if __FILE__ == $0
  graph = TerminalGraph.new
  cpucount = LinuxProcInfo.cpucount.to_f
  mem, swap = LinuxProcInfo.freemem
  LinuxProcInfo.loadavg.each { |n| graph << (n / cpucount) }
  graph << nil
  graph << (mem[0] - mem[1]) / mem[0].to_f
  graph << (swap[0] - swap[1]) / swap[0].to_f
  $stdout.puts(graph.render(0.0, 1.0))
end