From: Simon Strandgaard <neoneye@...>
Date: 2004-02-11T00:54:58+09:00
Subject: Re: capture stderr

On Tue, 10 Feb 2004 08:17:06 -0700, Ara.T.Howard wrote:
> On Tue, 10 Feb 2004, Simon Strandgaard wrote:
>> From: Simon Strandgaard <neoneye@adslhome.dk>
>> 
>> I want to temporarily capture stderr output.  Im on a freebsd box, so pipe
>> should work.
> 
> a pipe should work - but it's pretty tricky...

Yes I got the pipe working.. didn't you see my second mail?  ;-)

 
>> What am I doing wrong?
> 
> * IO#read blocks until eof is read - your loop will only happen once and tries
>   to read all data at once.  if you really wanted to do something like that
>   you'd need to do something like
> 
>     require 'io/nonblock' # i love this module

I have not yet tried using this module module.. though I have experience
with non-blocking io.  


[snip]
>       begin
>         $stderr = StringIO.new
>         yield
>         $stderr.rewind && $stderr.read
>       ensure
>         $stderr = STDERR
>       end

Thanks.. I had forgotten the 'ensure' statement!

My code is now looking like:

	def capture_stderr(&block)
		e = StringIO.new
		$stderr = e
		block.call
		return e.string
	ensure
		$stderr = STDERR
	end 


--
Simon Strandgaard