Split logging

logging.rb

# Capture stdout and stderr in a named file (while still writing to current stdout and stderr) for a block then restore old behaviour
  def capture_output(file)

    read, write = IO.pipe

    pid = fork

    unless pid
      write.close
      $stdin.reopen(read)
      exec "tee", file
    end

    read.close

    oldout = $stdout.dup
    olderr = $stderr.dup

    begin 
      $stdout.reopen(write)
      $stderr.reopen(write)
      $stdout.sync = true
      $stderr.sync = true
      
      yield
    ensure
      $stdout.reopen oldout
      $stderr.reopen olderr
    
      write.close
      Process.wait pid, Process::WUNTRACED
    end  
  end