example_expect.rb

# 
# 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 = false 
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 }>"