https://stackoverflow.com/questions/1871549/how-to-determine-if-python-is-running-inside-a-virtualenv

THIS

import os

running_in_virtualenv = bool(os.getenv("VIRTUAL_ENV"))

AND THAT

import sys

real_prefix = getattr(sys, "real_prefix", None)
base_prefix = getattr(sys, "base_prefix", sys.prefix)

running_in_virtualenv = (base_prefix or real_prefix) != sys.prefix

OR THIS

if [ $CONDA_DEFAULT_ENV ]        ## << note the spaces (important in BASH)!
    then
        printf 'venv: operating in tf-env, proceed ...'
    else
        printf 'Note: must run this script in tf-env venv'
        exit
fi
