randomized2

#!/usr/bin/env ruby

def usage
  $stderr.puts("Usage: #{File.basename($0)} <lines> <filename>")
  exit(1)
end

parameters = []
options = []
verbose = false

ARGV.each do |arg|
  if arg[0] == '-'
    options << arg
  else
    parameters << arg
  end
end

if parameters.length != 2 then
  usage()
end

options.each do |option|
  case option
  when '-v'
    verbose = true
  when '-h'
    usage()
  end
end

lines = parameters[0].to_i
filename = parameters[1]

if lines < 1
  $stderr.puts("at least one line please")
  exit(1)
end

filesize = File.size(filename)

File.open(filename) do |f|
  for i in 0...lines
    start = i * filesize / lines
    position = start + rand(filesize / lines)
    f.pos = position - 1
    f.gets
    puts f.gets
  end
end