Print size of specified files.

filesize.rb

#!/usr/bin/env ruby -w
# -*- coding: utf-8 -*-

# Print size of specified file(s) friendly and nicely for human beings

require 'optparse'

Version = '0.3.2'
Release = '2017-04-28'

class FileSize
  include Comparable

  def initialize(filename, parent_path)
    @filename = filename
    @parent_path = parent_path
    @bsize = 0
    @disp_size = 0
    @disp_suffix = ''

    calc
  end

  attr_reader :bsize, :disp_size, :disp_suffix

  def to_s
    "%s%s %s" % [size_str(@disp_size), @disp_suffix, @filename]
  end

  def <=>(other)
    @bsize <=> other.bsize if self.class === other
  end

  private
  def calc
    # Hmm..., I don't have any terabyte, petabyte or exabyte size file.
    path = File.expand_path(@filename, @parent_path)
    @bsize = FileTest.size(path)
    ksize = @bsize / 1024
    krest = @bsize % 1024
    msize = ksize / 1024
    mrest = ksize % 1024
    gsize = msize / 1024
    grest = msize % 1024

    if gsize > 0
      gsize += 1 if (grest > 0 or mrest > 0 or krest > 0)
      @disp_size, @disp_suffix = gsize, "G"
    elsif msize > 0
      msize += 1 if (mrest > 0 or krest > 0)
      @disp_size, @disp_suffix = msize, "M"
    elsif ksize > 0
      ksize += 1 if (krest > 0)
      @disp_size, @disp_suffix = ksize, "K"
    else
      @disp_size, @disp_suffix = @bsize, " "
    end
  end

  def size_str(size)
    "%4d" % size
  end
end

OPTS = {}
opt = OptionParser.new
opt.banner = "Usage: #{opt.program_name} [options] [files]"
opt.summary_width = 16
opt.version = Version
opt.release = Release
opt.on('-s', '--sort',
       'sort by size (descending order)') { |v| OPTS[:sort] = v }
opt.on('-r', '--reverse',
       'sort by size (ascending order)') { |v| OPTS[:reverse] = v }
opt.parse!(ARGV)

# When no files are specified, assume files in the current directory
# are specified.
files = ((ARGV.size > 0) ? ARGV : Dir.entries('.')).select do |e|
  path = File.expand_path(e)
  FileTest.exist?(path) and FileTest.file?(path)
end

result = files.reduce([]) do |r, f|
  r << FileSize.new(f, '.')
end

if result
  result.sort! { |x, y| y <=> x } if OPTS[:sort]
  result.sort! { |x, y| x <=> y } if OPTS[:reverse]

  result.each { |filesize| puts filesize.to_s }
end