From: "Ara.T.Howard" <ahoward@...>
Date: 2004-05-18T23:43:53+09:00
Subject: Re: PTY and expect tutorial and examples

On 17 May 2004, Bret Jolly wrote:

> Is there a tutorial or other simple documentation in English
> on how to use PTY and expect?  I'm having a heck of a time
> trying to figure them out.  I also cannot get the example
> scripts to work.  For example, expect_sample.rb comes with
> the ruby distribution (I'm using ruby 1.9.0 (2004-05-10) [i686-linux])
> and supposedly uses ftp to ftp.ruby-lang.org to get the name
> of the latest stable distribution.  Running this script tells
> me that the distribution is "nil" and I can't get it to work
> no matter how I hack it.  Even trying the simplest PTY program
> I can think of:
> 
> require 'pty'
> PTY.spawn("ls") { |r, w, pid|  puts r.readlines }
> 
> ...leads to failure with the exception PTY::ChildExited.
> 
> The most infuriating thing is that, despite not knowing what
> I am doing, I once had a Ruby expect script which invoked
> a function in Pari/gp and took the string result back into
> Ruby for further processing.  This script no longer works
> correctly (it gives answers, but wrong answers).  I can't
> figure out what is wrong because I don't understand PTY and
> expect and I can't find functioning examples or useful 
> documentation anywhere (the rdoc output is not useful documentation
> here).  Any pointers to explanations and examples that actually
> work will be greatly appreciated.  Thanks!
> 
> Regards, Bret

try this (untested on 1.9.0 but the example didn't work with 1.8.1 either -
this does):

#
# sample program of expect.rb
#
#  by A. Ito
#
#  This program reports the latest version of ruby interpreter
#  by connecting to ftp server at netlab.co.jp.
#
require 'pty'
require 'expect'

uri             = ARGV.shift || "ftp.ruby-lang.org"
STDOUT.sync     = true
STDERR.sync     = true
$expect_verbose = true
username        = ENV['USER'] || ENV['LOGNAME'] || username = 'guest'
versions        = []
login_pat       = %r/^\s*name.*:\s*/io
password_pat    = %r/^\s*password:/io
prompt_pat      = %r/^\s*ftp\s*>\s*/io
version_pat     = %r/ruby-(\d\.\d.\d)\.tar\.gz/io

PTY.spawn("ftp ftp.ruby-lang.org") do |r_f,w_f,pid|
  w_f.sync = true
  r_f.expect(login_pat){ w_f.puts "ftp" }
  r_f.expect(password_pat){ w_f.puts "#{ username }@" }
  r_f.expect(prompt_pat){ w_f.puts "cd pub/ruby" }
  r_f.expect(prompt_pat){ w_f.puts "dir" }
  r_f.expect(prompt_pat) do |output|
    output.first.each do |line| 
      m = version_pat.match(line)
      versions.push m[1] if m
    end
  end
  w_f.print("bye") rescue nil
end

puts versions.join ','
puts "The latest ruby interpreter is <#{ versions.sort.last }>"



-a
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