Prime numbers

prime.rb

#!/usr/bin/env ruby

def run max
  return unless max > 1

  return (2 .. max).inject([]) do |r, i|
    if i.even?
      r << i if i == 2
    else
      composite = false
      (3 .. Math.sqrt(i)).each do |t|
        if i % t == 0
          composite = true
          break
        end
      end

      r << i unless composite
    end

    r
  end

end

max = Integer(ARGV.shift)
puts run(max).join(' ')