Check if you are in a Python Virtual Environment

check-venv.sh

# 100% surefire way to detect a virtual environment: Check for the real_prefix system attribute.
echo $(python <<EOF
import sys
if(hasattr(sys, 'real_prefix')):
	print("Yes, you are in a virtual environment. (" + getattr(sys, 'real_prefix') + ")")
else:
	print("No, you are not in a virtual environment.")
EOF
)

# Not-as-good way, documented for posterity. See https://stackoverflow.com/a/1883251/2291928
# The $VIRTUAL_ENV environment variable gets set by the virtualenv active script,
# but that's not 100% reliable since you can start python in a virtual environment manually without activate.
# echo $VIRTUAL_ENV

Thanks for the script. However, it doesn't seem to work with new Python versions and latest virtualenv. For my needs, I have modified it to:

echo $(python <<EOF
import sys
if sys.prefix == sys.base_prefix:
    print("No, you are not in a virtual environment.")
else:
    print("Yes, you are in a virtual environment.")
EOF
)

To ensure support for older versions as well, look at https://stackoverflow.com/a/1883251/793930.