From: Jp Hastings-spital <jphastings@...>
Date: 2009-03-21T03:05:19+09:00
Subject: Re: Wrapping applications in Ruby

IO.popen method with io.each "\r" works spot on! Thanks so much!

Haven't tried working with Open3.popen3 yet, I may try reinstalling the 
gem.

Thanks for your replies, you've been patient and very helpful!

Robert Klemme wrote:
>> %\rEncoding: task 1 of 1, 0.18 %\rEncoding: task 1 of 1, 0.23 %
> If you have "\r" as line terminator, you can do the reading like this
> 
> io.each "\r" do |line|
>    # do whatever with line
> end

This makes it work beautifully!
> 
> e.g.
> 
> robert@fussel ~
> $ ruby -e '3.times {|i| printf "%03d\r", i}' | ruby -e
> '$stdin.each("\r") {|l| p l}'
> "000\r"
> "001\r"
> "002\r"
> 
> robert@fussel ~
> $
> 
>> $ cat wrapper.rb
>> input = "input.avi"
>> output = "output.mp4"
>> IO.popen("/usr/local/bin/HandBrakeCLI -i \"#{input}\" -o \"#{output}\"") 
>> { |stdout|
>>   p stdout.read
> 
> See above.
> 
>> }
>> 
>> This prints nothing! Am I right in thinking that the popen block gets 
>> called every time a \n character is captured by the pipe? (Your 
>> 'counting.rb' uses \n rather than \r - and works) Any ideas (other than 
>> say, passing the output through sed or something similar)?
>> 
>> Thanks again, JP
> 
> Note that the proper line reading (as suggested above) still does not
> help if the other program internally buffers IO.
> 
> Kind regards
> 
>   robert

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