fork_pipe_example.rb

#!/usr/bin/env ruby

# build our pipe to be shared between processes
# remember that pipes are unidirectional
r,w = IO.pipe

if fork
  # if we're here, we are the parent

  # close our copy of the read end because we don't use it
  r.close

  # send some data to across the pipe
  10.times do |n|
    w.puts n
  end

  # important to close all write ends of a pipe,
  # otherwise the read end will never EOF
  w.close

  # we wait for the child process to shutdown
  Process.wait
else
  # if we're here, we are the child

  # important to close all write ends of a pipe,
  # otherwise the read end will never EOF
  w.close

  # read off of the pipe until EOF
  while data = r.gets
    puts data
  end

  # close the reader
  r.close
end