Slick IO error handling for ruby shelled commands:

utils-subprocess.rb

# From: https://nickcharlton.net/posts/ruby-subprocesses-with-stdout-stderr-streams.html
require 'open3'

module Utils
  class Subprocess
    def initialize(cmd, &block)
      # see: http://stackoverflow.com/a/1162850/83386
      Open3.popen3(cmd) do |stdin, stdout, stderr, thread|
        # read each stream from a new thread
        { :out => stdout, :err => stderr }.each do |key, stream|
          Thread.new do
            until (line = stream.gets).nil? do
              # yield the block depending on the stream
              if key == :out
                yield line, nil, thread if block_given?
              else
                yield nil, line, thread if block_given?
              end
            end
          end
        end

        thread.join # don't exit until the external process is done
      end
    end
  end
end