diff --git a/makefiles/consts.mk b/makefiles/consts.mk
new file mode 100644
index 0000000..95d69a2
--- /dev/null
+++ b/makefiles/consts.mk
@@ -0,0 +1,44 @@
+# -*- makefile -*-
+# -----------------------------------------------------------------------
+# Copyright 2022 Open Networking Foundation (ONF) and the ONF Contributors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-FileCopyrightText: 2022 Open Networking Foundation (ONF) and the ONF Contributors
+# SPDX-License-Identifier: Apache-2.0
+# -----------------------------------------------------------------------
+
+$(if $(DEBUG),$(warning ENTER))
+
+null        :=#
+space       := $(null) $(null)
+dot         ?= .
+
+HIDE        ?= @
+
+env-clean   = /usr/bin/env --ignore-environment
+xargs-n1    := xargs -0 -t -n1 --no-run-if-empty
+
+## -----------------------------------------------------------------------
+## Not recommended but support (-u)ndef-less shell for pyenv activate
+## TODO: declare a pyenv shell
+## -----------------------------------------------------------------------
+have-shell-bash := $(filter bash,$(subst /,$(space),$(SHELL)))
+$(if $(have-shell-bash),$(null),\
+  $(eval export SHELL := /bin/bash -euo pipefail))
+
+shell-pyenv := bash -eo pipefail
+
+$(if $(DEBUG),$(warning LEAVE))
+
+# [EOF]