Question

I have a program that will trap Ctrl + c, but it can be trapped just once. When you type exit to exit from the irb session, the signal generated by Ctrl + c can’t be trapped again. Any ideas? This is the program:

require 'irb'
#trap "INT" do
#    IRB.start
#end

Signal.trap("INT")  { IRB.start }

count = 0

loop do
    count += 1
    puts count
    puts "Value = #{@value}" if defined? @value
    sleep 1
end

Answer 1

The problem is that IRB sets its own handler for sigint when you invoke it, which overrides your handler. To fix this, you can reset your handler again, after IRB is finished, like this:

def set_trap
  Signal.trap("INT")  do
    IRB.start
    set_trap
  end
end

set_trap

This will cause a bunch of warning when you invoke IRB the second time though, but that’s a general problem with invoking IRB multiple times.