From: Mike Barsalou <barjunk@...>
Date: 2009-08-25T07:50:06+09:00
Subject: Re: Asynchronous process to process pipe IO

On Aug 24, 1:05 pm, Gary Wright <gwtm...@mac.com> wrote:
> On Aug 24, 2009, at 4:54 PM, Pito Salas wrote:
>
>
>
> > Now, I am not exactly clear (reading the doc) about the difference
> > between exec and system... I do need to be able to send command line
> > arguments to iacommand.rb and I do indeed need to process the output  
> > 'as
> > it appears.'
>
> exec() causes a new program to be executed within the current process.
> Unless exec() fails (e.g. program not found), exec() will never 'return'
> because the current program will be discarded (i.e. the Ruby  
> interpreter)
> in favor of the newly exec'ed one.
>
> system() causes a new (child) process to be created and for the new
> program to be executed (i.e. exec'ed) within the new child process.
> The current process will wait for the child process to terminate before
> proceeding.
>
> The difference is whether the new program replaces the currently
> running program or not. Note that 'program' here means the Ruby
> interpreter and not the particular Ruby script that is running.
>
> Note: I'm answering from the perspective of a Unix/Posix environment.
> My windows-fu isn't sufficient to say if my description is correct
> for that environment, but it is probably pretty close.
>
> Gary Wright

Would Ruby's fork behave exactly like system here, or would it have a
third path?  Likely fork wouldn't be an option for the OP because he
wants to process the output?

Mike B.