From: Payton Swick <payton@...>
Date: 2006-01-31T04:24:38+09:00
Subject: IO.popen hangs reading an empty pipe?

How does one check a pipe (created using IO.popen) to see if there is 
input waiting without using IO#eof or reading from the pipe?  Doing 
either of these seems to hang forever if the pipe is empty.

Here's an example:

require 'timeout'
IO.popen("cat", "r+") do |pipe|
#   pipe.puts "hello world" # Uncomment this to prevent hang below.
   Timeout::timeout(2) do
     if not pipe.eof? # This will hang if the pipe is empty.
       p pipe.getc
     end
   end
end

-Payton