diff -ur v2/chat_conn.py v3/chat_conn.py
--- v2/chat_conn.py	2019-08-11 23:59:01.000000000 +0900
+++ v3/chat_conn.py	2019-08-13 12:57:29.000000000 +0900
@@ -5,6 +5,11 @@
 import select
 import time
 import threading
+import subprocess
+try:
+	import queue
+except:
+	import Queue as queue
 
 tmout = 3.0
 
@@ -377,18 +382,18 @@
 
 	return e.to_attr( locals() )
 
-def cli(host, port, name0):
+def client(host, port, name0, func_in, func_out):
 	cli = cli_new(host, port, name0)
 	th_quit = threading.Event()
 
 	def th_func():
 		rest = rest_new()
 		while not th_quit.wait(0):
-			if not readable(sys.stdin):
-				continue
-			s = sys.stdin.readline()
-			if not s:
+			s = func_in()
+			if s == False:
 				break
+			if not s:
+				continue
 			cli.send_to('', s)
 
 	th = threading.Thread( target=th_func )
@@ -404,15 +409,40 @@
 		(f, s) = r
 		if f:
 			s = '{}> {}'.format(f, s)
-		print(s)
+		func_out(s)
 
 	th_quit.set()
 	th.join()
 	cli.dis_conn()
 
+def cmd_io_new(cmd):
+	que = queue.Queue()
+
+	def func_in():
+		s = None
+		if cmd:
+			try:
+				s = que.get(timeout=tmout)
+			except:
+				s = None
+		elif readable(sys.stdin):
+			s = sys.stdin.readline().strip()
+		return s
+
+	def func_out(s):
+		if cmd:
+			echo_cmd = 'echo "{}" | {}'.format(s, cmd)
+			ret = subprocess.check_output(echo_cmd, shell=True).decode('utf-8').strip()
+			if ret:
+				que.put(ret)
+		else:
+			print(s)
+
+	return Empty( locals() )
+
 def help(v):
 	ss = [
-		'Usage: {} <port> [conn [<user name>] [<hostname>]]'.format(sys.argv[0]),
+		'Usage: {} <port> [conn [<user name>] [host=<hostname>] [cmd=<cmd>]]'.format(sys.argv[0]),
 		'  conn: client mode',
 		'  user name: default "guest"',
 		'  hostname: default "localhost"',
@@ -421,21 +451,27 @@
 	sys.exit(v)
 
 if __name__ == "__main__":
-	arg = lambda i, def_v=None: sys.argv[i] if sys.argv[i:] else def_v
+	av = sys.argv[1:]
+	pop = lambda def_v=None: av.pop(0) if av else def_v
+	def pop_k(k, def_v=None):
+		for i in range( len(av) ):
+			if av[i].startswith(k):
+				return av.pop(i)[ len(k): ]
+		return def_v
 
-	port = int( arg(1, '-1') )
+	port = int( pop('-1') )
 	if port < 0:
 		help(1)
-
-	kind = arg(2)
+	kind = pop()
 	if not kind:
 		srv(port)
 		sys.exit(0)
 	if kind != 'conn':
-		help(2)	
-
-	name0 = arg(3, 'guest')
-	host = arg(4, 'localhost')
+		help(2)
+	host = pop_k('host=', 'localhost')	
+	cmd = pop_k('cmd=', '')
+	name0 = pop('guest')
+	cmd_io = cmd_io_new(cmd)
 
-	cli(host, port, name0)
+	client(host, port, name0, cmd_io.func_in, cmd_io.func_out)
 # EOF