From: Tim Hunter <TimHunter@...>
Date: 2007-10-15T04:38:30+09:00
Subject: Re: Capturing the output of an external program line by line

Aditya Mahajan wrote:
> Hi,
> 
> I want to run an external program in ruby. The external program takes a 
> long time to execute. While running, it gives the information on stdout 
> about what it is doing. How can I run the external program inside ruby 
> so that I can capture this information, and display it on stdout? I 
> tried %x{...}, `...` and system("...."), but all of them give me a 
> result AFTER the external program has finished executing, not during its 
> execution.
> 
> Thanks,
> Aditya
> 
I've been using this:

	  IO.popen("#{cmd} 2>&1") do |f|
	    while line = f.gets do
	      # do whatever you want with line
	    end
	  end

Note that this gets both stdout and stderr.

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