From: Harold Hausman <hhausman@...>
Date: 2007-02-23T10:12:10+09:00
Subject: Re: IO.popen on Windows to filter stdout

On 2/22/07, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov> wrote:
> On Thu, 22 Feb 2007, Harold Hausman wrote:
>
> > <snip...>
> >
> > Of course, this is on windows, so I don't have proper fork, etc...
> >
> > Is there a way to somehow "swallow" the stdout from the sub process so it
> > doesn't make it directly to the ruby process' stdout?
>
> probably the other process is writing to stderr.  try
>
>    IO.popen( 'cmd 2>&1' ) do |pipe|
>      pipe.each do |line|
>        p line
>      end
>    end
>

Hi Ara, thanks for taking the time to try and help me. What you're
saying about stderr here sounds right to me, but I tried what you have
above, and I'm still seeing the output I'm trying to 'squash' (read:
block) ... Here is my code:
#########################
puts "ruby-link in the house!"
the_cmd = "old-Link.exe "
ARGV.each do |arg|
	the_cmd << "\"#{arg}\" "
end

the_cmd << "2>&1"

puts "Calling: #{the_cmd}"

IO.popen( the_cmd )
#########################

And here is the output that I see: (apologies for badly wrapped lines)
ruby-link in the house!
Calling: old-Link.exe "@C:\long\path\to\some.rsp" "/NOLOGO"
"/ERRORREPORT:PROMPT" 2>&1
OLD-LINK :
<snip about 200k of nasty output from old-Link.exe>

------
So yeah, the output from old-Link.exe is still being filtered up to
the top and seen. What I'm looking for is a way to shut it up... ;)

> alternatively, you may want to use systemu
>
>    http://codeforpeople.com/lib/ruby/systemu
>

I looked at systemu and it's not clear how it would help with this
problem. :| Apologies if I'm being dense.

> it's __very__ easy to block a process using IO.popen on windows.
>

I thought so too. ;)

Thanks again for your time,
-Harold