From: Robert Klemme <shortcutter@...>
Date: 2010-01-21T17:27:17+09:00
Subject: Re: capture output in real time

2008/5/10 ara.t.howard <ara.t.howard@gmail.com>:
>
> On May 9, 2008, at 6:08 PM, Paul Winward wrote:
>>
>> Note, I'm avoiding STDOUT.flush in sleep.rb since I won't be able to
>> change the actual scripts I'll be passing to popen3.
>
> popen3 is going to be using fork/exec under the hood and should inherit the
> sync setting of STDOUT, so try setting
>
>  STDOUT.sync = true
>
> before the popen and see if that helps - untested, but i'm running out the
> door....

IMHO that can only work if you use fork with a block.  Since Paul
wants to start a new process that cannot possibly inherit buffering
settings that way.  Since Ruby decides buffering mode of stdout based
on the type (i.e. if it is a terminal then sync = true otherwise not)
and the child process cannot be influenced by Paul it follows that the
only feasible way to use would be to present a tty as stdout to the
child (via some form of pseudo tty mechanism).  But that may have
adverse effects because some programs change their output based on the
type of stdout as well (just think about including colorization on
ttys and omitting it on pipes).

This is the place to ask: Paul, what do you need that behavior for?
Maybe there are other mechanism to use.

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/