singals_and_subprocesses.rb

# Simple test to see how subprocesses handle signals.

# The result is that the terminal sends the INTERRUPT signal to both the
# main process and subprocesses.
# If you use the `kill` command on the main process' pid, subprocesses don't
# respond.

def forking
  Signal.trap('INT') { puts "INT Trapped"; exit }
  5.times do
    fork do
      sleep 10
    end
  end
  Process.waitall
end

def execing
  Signal.trap('INT') { puts "INT Trapped"; exit }
  fork do
    exec %(ruby -e "sleep 10; puts 'done'")
  end
  Process.waitall
end

def exec_with_handler
  Signal.trap('INT') { puts "INT Trapped"; exit }
  fork do
    exec %(ruby -e "Signal.trap('INT') { puts 'INT Trapped'; exit }; sleep 10; puts 'done'")
  end
  Process.waitall
end

send(ARGV[0])

__END__
Results:

$ ruby signals_and_subprocesses forking
^CINT Trapped
INT Trapped
INT Trapped
INT Trapped
INT Trapped

$ ruby signals_and_subprocesses execing
^CINT Trapped
-e:1:in `sleep': Interrupt
  from -e:1

$ ruby signals_and_subprocesses exec_with_handler
^CINT Trapped
INT Trapped