Quit IPython on Ctrl-\ (SIGQUIT)

Closes  #9810

IPython/terminal/shortcuts.py

@@ -26,6 +26,8 b' def register_ipython_shortcuts(registry, shell):'
                                  & insert_mode
                         ))(newline_or_execute_outer(shell))
 
+    registry.add_binding(Keys.ControlBackslash)(force_exit)
+
     registry.add_binding(Keys.ControlP,
                          filter=(ViInsertMode() & HasFocus(DEFAULT_BUFFER)
                         ))(previous_history_or_previous_completion)
@@ -145,6 +147,12 b' def reset_search_buffer(event):'
 def suspend_to_bg(event):
     event.cli.suspend_to_background()
 
+def force_exit(event):
+    """
+    Force exit (with a non-zero return value)
+    """
+    sys.exit("Quit")
+
 def indent_buffer(event):
     event.current_buffer.insert_text(' ' * 4)