Run a shell command and pipe the stdout to to parent process.

gistfile1.rb

task :test do
  cmd = 'shell command to run'
  rd, wr = IO::pipe
  pid = Process.fork do
    $stdout.reopen(wr)
    rd.close
    exec(cmd)
  end
  wr.close
  rd.each { |line| puts line }
  Process.wait(pid)
end