Is there an Expect equivalent gem for Ruby?

Question

Is there an Expect equivalent gem for Ruby?

I tried searching on code.google and rubygems.org, but sadly it did not show up.

FYI: Expect is a Unix automation and testing tool, written by Don Libes as an extension to the Tcl scripting language, for interactive applications such as telnet, ftp, passwd, fsck, rlogin, tip, ssh, and others.

Answer 1

Ruby comes with the PTY module for setting up pseudoterminals to drive interactive command line applications. With it comes an expect method that allows you to interact with an application kinda like Expect. For learning how to use expect, I found "What to expect from the Ruby expect library?" helpful.

As far as gems go, maybe checkout greenletters which is supposed to improve upon PTY + expect (although I haven't tried it myself).

Answer 2

I recently spent quite a bit of time struggling with this issue (I am stuck with 1.8.7). I found this question, this blog post and this forum thread really useful.

At the end this is my application code if anyone is interested in a little example (pass the password to rpm when signing packages):

def run_interactive command, password, promt
  output   = ''
  begin
    r, w, pid = PTY.spawn(command)
    puts r.expect(promt)
    sleep(0.5)
    w.puts(password)
    begin
      r.each { |l| output += l } 
    rescue Errno::EIO
    end
    $?.exitstatus
    Process.wait(pid)
  rescue PTY::ChildExited => e
    $stderr.puts "The child process #{e} exited! #{$!.status.exitstatus}"
  end 
  output
end

password = "mypassword"
command  = "rpm --define '_signature gpg' --define '_gpg_name #{key_id}' --addsign #{package}"
promt    = %r{.*: }
expected = %r{good}
output = run_interactive(command, password, promt)
if output.match(expected)
  puts output
else
  abort "Error: expected: '#{expected}' got '#{output}'"
end 

It has little error checking but it was all I needed.

Edit: Update the code with Process.wait(pid) to make sure it finishes before continuing and add comment about this being for 1.8.7.

Answer 3

checkout this rubygem: https://github.com/abates/ruby_expect. It could handle some small task for you. from its official example, it's enough to 'enter password' and login and interactive with local script.

here is an example that update the git code (which is authenticated with password):

require 'rubygems'
require 'ruby_expect'

def update_code
  password = 'your password here'
  exp = RubyExpect::Expect.spawn('git pull', :debug => true)
  exp.procedure do
    each do
        expect /password: / do
            send password
        end
    end
  end
end

update_code

just run the code above, and your will see like this:

$ ruby update_code.rb 

shensiwei@gforge.1ver??.net's password: 
remote: Counting objects: 133, done.
remote: Compressing objects: 100% (84/84), done.
remote: Total 85 (delta 62), reused 0 (delta 0)
Unpacking objects: 100% (85/85), done.

for more example and details, please dive into its source code.

Answer 4

expect4r seems to do what you are asking for, though it is made specific for connections to Cisco and Juniper devices.

Perhaps even better is yax as this is "yet another expect".

Answer 5

RExpect

From the project's website:

RExpect is a drop in replacement for the expect.rb module in the standard library that is faster and more robust, cabable of driving many devices simultaneously.

Answer 6

parley is another one you can try, (written by me). It is inspired by Perl expect.