diff --git a/__init__.py b/__init__.py
index f414966..2a2409b 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import time
diff --git a/aux.py b/aux.py
index 3edd3e8..d2aa393 100644
--- a/aux.py
+++ b/aux.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import sys
diff --git a/core/__init__.py b/core/__init__.py
index 13db0b4..59487ef 100644
--- a/core/__init__.py
+++ b/core/__init__.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 from . import app
diff --git a/core/app.py b/core/app.py
index bd9f6b2..c26eae7 100644
--- a/core/app.py
+++ b/core/app.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import os
diff --git a/core/aux.py b/core/aux.py
index 53d020a..5059288 100644
--- a/core/aux.py
+++ b/core/aux.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import sys
diff --git a/core/cmd.py b/core/cmd.py
index 4cc2963..6045017 100644
--- a/core/cmd.py
+++ b/core/cmd.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import queue
@@ -66,6 +66,7 @@ class Command:
 		self.__dict__['thread'] = None
 		self.__dict__['fifo'] = None
 		self.__dict__['terminated'] = False
+		self.__dict__['returncode'] = None
 	
 	def dump(self, sequence=None, pretty=False):
 		out = []
diff --git a/core/file.py b/core/file.py
index 9315913..f793f91 100644
--- a/core/file.py
+++ b/core/file.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import os
diff --git a/core/misc.py b/core/misc.py
index be2cefe..80edd83 100644
--- a/core/misc.py
+++ b/core/misc.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import copy
diff --git a/core/python_types.py b/core/python_types.py
index 801e0f2..3dbd001 100644
--- a/core/python_types.py
+++ b/core/python_types.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 # --------------------------------------------------
diff --git a/core/text.py b/core/text.py
index 848e9ee..4ffdbee 100644
--- a/core/text.py
+++ b/core/text.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import math
diff --git a/m/__init__.py b/m/__init__.py
index 8d143d4..569ddfd 100644
--- a/m/__init__.py
+++ b/m/__init__.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 #
 # Part of Project Overwatch
diff --git a/m/python_m.py b/m/python_m.py
index a4310a7..d1fb0a5 100644
--- a/m/python_m.py
+++ b/m/python_m.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 '''
diff --git a/serial/com.py b/serial/com.py
index eedf43d..6b075c4 100644
--- a/serial/com.py
+++ b/serial/com.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 import time
diff --git a/version.py b/version.py
index 91b177c..5b83190 100644
--- a/version.py
+++ b/version.py
@@ -1,4 +1,4 @@
-#! /bin/env python3
+#! /usr/bin/env python3
 # encoding: utf-8
 
 _version = (0, '00000000') # OVER_VERSION_IDENTIFIER