ruby popen3 — how to repeatedly write to stdin & read stdout without re-opening process?

Question

I am using Open3\'s popen3 method to start a process that functions in a console-like / REPL fashion to repeatedly accept input and return output.

I am able to open

Answer 1

You can have some success using expect library, and have the child process to explicitly mark the end of each output, like:

require 'expect'
require 'open3'

Open3.popen3("/bin/bash") do
    | input, output, error, wait_thr |
    input.sync = true
    output.sync = true

    input.puts "ls /tmp"
    input.puts "echo '----'"
    puts output.expect("----", 5)

    input.puts "cal apr 2014"
    input.puts "echo '----'"
    puts output.expect("----", 5)
end

As a bonus, expect has a timeout option.