diff -ur v7/sock_ut.py v8/sock_ut.py
--- v7/sock_ut.py	2021-07-14 22:40:49.000000000 +0900
+++ v8/sock_ut.py	2021-07-16 10:25:21.000000000 +0900
@@ -11,6 +11,10 @@
 
 can_read = lambda sc, tmout=0: select.select( [ sc ], [], [], tmout )[ 0 ] == [ sc ]
 
+add_tail = lambda s, add: s + add
+
+cut_tail = lambda s, cut: s[ : -len( cut ) ] if s.endswith( cut ) else s
+
 def port_conn( port, host='localhost' ):
 	cs = socket.socket( socket.AF_INET, socket.SOCK_STREAM )
 	try:
@@ -40,16 +44,19 @@
 	return buf
 
 def send_str( sc, s ):
+	s = add_tail( s, '\n' )
 	bt = s.encode( 'utf-8' )
 	return send_bt( sc, bt )
 
 def recv_str( sc, bufmax=16*1024 ):
-	bt = recv_bt( sc, bufmax )
-	return bt.decode( 'utf-8' )
+	bt = recv_bt( sc, bufmax + 1 )  # '\n'
+	s = bt.decode( 'utf-8' )
+	return cut_tail( s, '\n' )
 
 def recv_str_all( sc ):
 	bt = recv_bt_all( sc )
-	return bt.decode( 'utf-8' )
+	s = bt.decode( 'utf-8' )
+	return cut_tail( s, '\n' )
 
 def pipe_loop( sc_from, sc_to ):
 	while True: