From: Mark Wilson <mwilson13@...>
Date: 2003-02-10T12:22:33+09:00
Subject: Re: Executing interactive system commands


On Sunday, February 9, 2003, at 09:15 PM, Vitaly Semkin wrote:

> Vitaly Semkin wrote:
>> Hello.
>> I need to execute SCP (secure copy) command from Ruby script on 
>> Windows.
>> The problem is that this command needs a password to be typed and 
>> supports no switch or option to provide the password.
>> Is there any way to catch the command's output and give it the 
>> passwod?
> [snip]

Expect is made to do what you want. There is a Windows version, 
although I've never used it. See the following website:

http://expect.nist.gov/

There is something similar built into Ruby, expect.rb, which is in the 
standard library for 1.6.8. I have not used it, but it may do what you 
want. It is also short enough to reproduce here:

$expect_verbose = false

class IO
   def expect(pat,timeout=9999999)
     buf = ''
     case pat
     when String
       e_pat = Regexp.new(Regexp.quote(pat))
     when Regexp
       e_pat = pat
     end
     while true
       if IO.select([self],nil,nil,timeout).nil? then
         result = nil
         break
       end
       c = getc.chr
       buf << c
       if $expect_verbose
         STDOUT.print c
         STDOUT.flush
       end
       if mat=e_pat.match(buf) then
         result = [buf,*mat.to_a[1..-1]]
         break
       end
     end
     if iterator? then
       yield result
     else
       return result
     end
     nil
   end
end