t.rb

code = 'system gets; puts "end"'
host = "tsukuba100"
cmd = "ssh -x -T #{host} \"ruby -e 'eval ARGF.read(#{code.size})'\""
 
r0,w0 = IO.pipe
r1,w1 = IO.pipe
pid = spawn(cmd,:in=>r0,:out=>w1)
 
w0.write(code)
w0.puts("hostname")
 
while s = r1.gets
  break if s.chomp == "end"
  puts s
end