title: Pipe output with expect spawn
body: <p>I have script for copying some files by ssh to other server. I'm using tar for compressing files to on farchive and decompress it from stdout on other machine.</p>
  
  <pre><code>set timeout -1
  
  # user info
  set port [lindex $argv 0]
  set login [lindex $argv 1]
  set password [lindex $argv 3]
  set host [lindex $argv 2]
  
  #tar info
  set sdir [lindex $argv 4]
  set ddir [lindex $argv 5]
  
  spawn tar cf - $sdir | ssh -p $port $login@$host tar xf - -C $ddir
  
  expect "*?(yes/no)" {
      send "yes\r"
  }
  
  expect "*?assword" {
      send "$password\r"
  }
  
  expect "#" {
      send "ls $ddir -la\r"
  }
  
  expect "#" {
      send "exit\r"
  }
  
  interact
  </code></pre>
  
  <p>But '|' doesn't work with spawn. I tried to find any solution, but there no any suitable way for me. Can you give me an advice for this question?</p>