Loop until gets stop

until_gets_stop.rb

Thread.new do
  # Do this in a new thread so that the loop can run at the same time as gets (the latter waits until a newline is entered)
  until gets.chomp == "stop"; end
  # Exit the entire program (this only stops the current thread in IRB, I warn you)
  exit
end

puts "Program started"
loop do
  sleep 5
  puts "Hello? Anyone here?"
end