title: Better handling of KeyboardInterrupt in cmd.Cmd command line interpreter
body: <p>While using python's cmd.Cmd to create a custom CLI, how do I tell the handler to abort the current line and give me a new prompt?</p>
  
  <p>Here is a minimal example:</p>
  
  <pre><code># console_min.py
  # run: 'python console_min.py'
  
  import cmd, signal
  
  class Console(cmd.Cmd):
      def __init__(self):
          cmd.Cmd.__init__(self)
          self.prompt = "[test] "
          signal.signal(signal.SIGINT, handler)
  
      def do_exit(self, args):
          return -1
  
      def do_EOF(self, args):
          return self.do_exit(args)
  
      def preloop(self):
          cmd.Cmd.preloop(self)
          self._hist    = []
          self._locals  = {}
          self._globals = {}
  
      def postloop(self):
          cmd.Cmd.postloop(self)
          print "Exiting ..."
  
      def precmd(self, line):
          self._hist += [ line.strip() ]
          return line
  
      def postcmd(self, stop, line):
          return stop
  
      def emptyline(self):
          return cmd.Cmd.emptyline(self)
  
      def handler(self, signum, frame):
          # self.emptyline() does not work here
          # return cmd.Cmd.emptyline(self) does not work here
          print "caught ctrl+c, press return to continue"
  
  if __name__ == '__main__':
      console = Console()
      console.cmdloop()
  </code></pre>
  
  <p>Further help is greatly appreciated.</p>
  
  <p>Original Question and more details:
  [Currently the suggestions below have been integrated into this question -- still searching for an answer. Updated to fix an error.]</p>
  
  <p>I've since tried moving the handler to a function outside the loop to see if it were more flexible, but it does not appear to be.</p>
  
  <p>I am using python's <a href="http://wiki.python.org/moin/CmdModule" rel="noreferrer">cmd.Cmd module</a> to create my own command line interpreter to manage interaction with some software. I often press ctrl+c expecting popular shell-like behavior of returning a new prompt without acting on whatever command was typed. However, it just exits. I've tried to catch KeyboardInterrupt exceptions at various points in the code (preloop, etc.) to no avail. I've read a bit on <a href="https://stackoverflow.com/questions/1112343/how-do-i-capture-sigint-in-python">sigints</a> but don't quite know how that fits in here.</p>
  
  <p>UPDATE: From suggestions below, I tried to implement signal and was able to do so such that ctrl+c now doesn't exit the CLI but does print the message. However, my new issue is that I cannot seem to tell the handler function (see below) to do much beside print. I would like ctrl+c to basically abort the current line and give me a new prompt.</p>