Forward SIGINT to current pipe process instead of terminating it. This is consistent

with our do_shell() command, ppaged() command, and other shells.

Author: kmvanbrunt

cmd2/cmd2.py

@@ -1659,8 +1659,8 @@ def sigint_handler(self, signum: int, frame) -> None:
         :param frame
         """
         if self.cur_pipe_proc_reader is not None:
-            # Terminate the current pipe process
-            self.cur_pipe_proc_reader.terminate()
+            # Pass the SIGINT to the current pipe process
+            self.cur_pipe_proc_reader.send_sigint()
 
         # Check if we are allowed to re-raise the KeyboardInterrupt
         if not self.sigint_protection:
@@ -1933,8 +1933,8 @@ def _redirect_output(self, statement: Statement) -> Tuple[bool, RedirectionSaved
             # We want Popen to raise an exception if it fails to open the process.  Thus we don't set shell to True.
             try:
                 # Set options to not forward signals to the pipe process. If a Ctrl-C event occurs,
-                # our sigint handler terminate the most recent pipe process. This makes sure
-                # pipe processes close in the right order (most recent first).
+                # our sigint handler will forward it only to the most recent pipe process. This makes
+                # sure pipe processes close in the right order (most recent first).
                 if sys.platform == 'win32':
                     creationflags = subprocess.CREATE_NEW_PROCESS_GROUP
                     start_new_session = False

cmd2/utils.py

@@ -404,6 +404,11 @@ def __init__(self, proc: subprocess.Popen, stdout: Union[StdSim, BinaryIO, TextI
         if self._proc.stderr is not None:
             self._err_thread.start()
 
+    def send_sigint(self) -> None:
+        """Send a SIGINT to the process"""
+        import signal
+        self._proc.send_signal(signal.SIGINT)
+
     def terminate(self) -> None:
         """Terminate the process"""
         self._proc.terminate()