From: Robert Klemme <shortcutter@...>
Date: 2011-03-25T19:27:58+09:00
Subject: Re: Pid of the other end of a popen3?

On Fri, Mar 25, 2011 at 10:58 AM, Alex Young <alex@blackkettle.org> wrote:
> Is it possible to get the pid of a process at the other end of an IO
> returned by Open3.popen3?  I'm doing something not dissimilar to this:
>
>
>  Open3.popen3("other_process") do |ior, iow, ioe|
>    otherpid = ior.pid
>
>    raise "Oh no!" if otherpid.nil?
>  end
>
>
> And it always raises. Looking at the source for Open3.popen3, it looks
> like the child pid gets swallowed by the double-fork. Is there any way
> to get it back?

What "double fork"?  It seems you are using the wrong method:

irb(main):021:0> Open3.popen3("sleep", "5") {|a,b,c,t| p a.pid, t[:pid]}
nil
2112
=> [nil, 2112]

See ri Open3.popen3.

Cheers

robert


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