From: James Dinkel <jdinkel@...>
Date: 2008-09-11T15:37:33+09:00
Subject: Re: How to execute files or commands in ruby?

I use popen3 because I usually want to capture any output to stderr as
well as stdout.  Here is an example:

Open3.popen3("commandname") do |input_stream, output_stream,
error_stream|
  standard_output = output_stream.read
  standard_error = error_stream.read
end

The variables "standard_output" and "standard_error" will be string
variables at that point, containing the text of the error and output
streams.  I haven't had a need to use stdin, but I suspect calling the
'write' method on "input_stream" would be be the equivalent of piping
information to the command.  However, it may also provide a method of
scripting an interactive command.

You can also use it without a block like this:

[input_stream, output_stream, error_stream] =
Open3.popen3("commandname")

You then have an array containing the IO streams, and then you could
call the 'read' method on the streams just as above, although I've
always used the block form.

James
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