Run system command in ruby and interact with it

command-line, command-line-interface, pgp, ruby

Solution

The Unix way to handle these situations is with expect, which Ruby comes with built-in support for:

require 'pty'
require 'expect'

PTY.spawn("your command here") do |reader, writer|
  reader.expect(/Use this key anyway/, 5) # cont. in 5s if input doesn't match
  writer.puts('y')
  puts "cmd response: #{reader.gets}"
end

Problem

I need to run a command on the command-line that asks for a user response. In case it helps the command is: ``` gpg --recipient "Some Name" --encrypt ~/some_file.txt ``` when you run this, it warns about something then asks: Use this key anyway? (y/N) Responding 'y' let's it finish correctly. I have been trying to use the open4 gem but I have not been able to get it to specify the 'y' correctly. Here is what I tried: ``` Open4::popen4(cmd) do |pid, stdin, stdout, stderr| stdin.puts "y" stdin.close puts "pid : #{ pid }" puts "stdout : #{ stdout.read.strip }" puts "stderr : #{ stderr.read.strip }" end ``` What am I doing wrong? Is what I am doing even possible?

Original source