From: nobu.nokada@...
Date: 2004-04-15T14:58:49+09:00
Subject: Re: ruby pty/expect help

Hi,

At Thu, 15 Apr 2004 12:09:12 +0900,
Ara.T.Howard wrote in [ruby-talk:97212]:
> perhaps a handle on an object which can be 'closed' could be returned instead
> of an array of Files, etc:
> 
>   passphrase = gen_random_passphrase
> 
>   pty = PTY.spawn 'ssh-keygen'
> 
>   pty.stdin.puts 'id_rsa.pub' 
>   pty.stdin.puts passphrase
>   pty.stdin.puts passphrase
>   pts.close  # do the right thing

Yes, I've thought about same strategy for open3.

> 
>   pty = PTY.spawn 'ssh-agent'
> 
>   pty.stdin.write passphrase
> 
>   ...
> 
> 
> > BTW, you don't need PTY at all to generate ssh key
> > automatically.
> 
> see above - i want to pass it to ssh-agent.  thanks though, didn't know
> that...

ssh-agent doesn't read passphrase but prints some environment
variables and runs as a daemon, like as:

  $ ssh-agent
  SSH_AUTH_SOCK=/tmp/ssh-FGmutb8164/agent.8164; export SSH_AUTH_SOCK;
  SSH_AGENT_PID=8165; export SSH_AGENT_PID;
  echo Agent pid 8165;

Therefore you should set those variables instead. e.g.,

  `ssh-agent`.scan(/^(SSH_[A-Z_]+)=([^; ]*)/, &ENV.method(:[]=))

Then, you'll need to send passphrase to ssh-add.  At this time,
you have 2 methods:

1) with pty.
    PTY.spawn("ssh-add") do |r,w,pid|
      r.expect %r/^Enter.*:\s+/ {w.puts passphrase}
    end

2) without control terminal.  Since ssh-add reads passphrase
   from stdin when no ctty or X are available, you can:

    IO.popen("-", "w") do |f|
      if f
        f.puts passphrase
      else
        ENV.delete("SSH_ASKPASS")
        ENV.delete("DISPLAY")
        Process.setsid
	exec("ssh-add")
      end
    end

   or, if setsid command is available and env command has -u option:

    IO.popen("env -u SSH_ASKPASS -u DISPLAY setsid ssh-add", "w") do |f|
      f.puts passphrase
    end

-- 
Nobu Nakada