diff --git a/bill_man b/bill_man
index 72bdfd4..73a4766 100755
--- a/bill_man
+++ b/bill_man
@@ -1,3 +1,35 @@
 #!/bin/bash
 
-PATH=$VIRTUAL_ENV/bin:$PATH exec python bill_man.py $1
+PYTHON_VERSION="X$(python -V 2>&1)"
+if [[ "X$?" == "X0" && "X$(echo ${PYTHON_VERSION}|cut -f 2 -d ' ' |cut -f 1 -d '.')" == "X3" ]] ; then
+    PYTHON="$(which python)"
+fi
+
+PYTHON_VERSION="X$(python3 -V 2>&1)"
+if [[ "X$?" == "X0" && "X$(echo ${PYTHON_VERSION}|cut -f 2 -d ' ' |cut -f 1 -d '.')" == "X3" ]] ; then
+    PYTHON="$(which python3)"
+fi
+
+if [[ "X${PYTHON}" == "X" ]] ; then
+    (>&2 echo "python3 not detected")
+    exit 1
+else
+    (>&2 echo "detected python3 : ${PYTHON}")
+fi
+
+if [[ "X${VIRTUAL_ENV}" == "X" ]] ; then
+    VIRTUAL_ENV="$(pwd)/venv"
+fi
+
+if [[ ! -d "${VIRTUAL_ENV}" && ! -x "${VIRTUAL_ENV}/bin/activate" ]] ; then
+    (>&2 echo "virtual envioment not detected. let's installing.... in ${VIRTUAL_ENV}")
+    "${PYTHON}" -m venv "${VIRTUAL_ENV}"
+    source "${VIRTUAL_ENV}/bin/activate"
+    pip install -r requirements.txt
+else
+    (>&2 echo "detected virtual environment : ${VIRTUAL_ENV}")
+    source "${VIRTUAL_ENV}/bin/activate"
+fi
+PYTHON="${VIRTUAL_ENV}/bin/python"
+
+exec python bill_man.py $@