From: "yermej@..." <yermej@...>
Date: 2007-09-25T07:10:04+09:00
Subject: Re: communicating w/ command-line program (OR ruby expect)

On Sep 24, 4:57 pm, "Cameron Matheson" <cameron.mathe...@gmail.com>
wrote:
> Hello,
>
> I'm trying to communicate w/ a command-line process w/ ruby.  I
> thought IO.popen would be the right tool for the job, but I need to be
> able to read and write to the process, and I can't get it to work
> (i've googled for examples, but everything I have seen is only doing
> one-way communication).  Anyway, it looks like what I need is
> something like "Expect" for ruby.  Does anyone know if such a tool
> exists?  (Or any other way in which I could read/write from a
> command-line program).
>
> Thanks!
> Cam

If you're just calling a command line tool like grep or something
(reads standard input and then returns result to standard out),
IO.popen is what you need:

cmd_output = IO.popen "cmd -args some stuff", 'r+' do |pipe|
  pipe.write the_input
  pipe.close_write
  pipe.read.chomp
end

if $? == 0
  # success, do something
else
  # cmd exited with an error, deal with it
end

If you need to interact with something (a la irb, ftp, telnet, etc.)
you'll need to find something else, I think.

Jeremy