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Virtual environments

These steps will help you list all the virtual environment management tools available on your Kali system.

Check System-Wide Package Managers for Installed Tools:

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# Using APT (Default Kali Package Manager)
dpkg --get-selections | grep -E "pyenv|virtualenv|pipenv|conda"

# Using pip to List Installed Python Packages
pip list | grep -E "virtualenv|pipenv|pyenv|conda"


# Verify Installed Tools' Locations
which pyenv
which virtualenv
which pipenv
which conda

Python vs. pyenv

We may have two different Python environments on the system:

  1. System Python (Managed by update-alternatives)

    • Installed globally in /usr/bin/python, /usr/bin/python3.x
    • Used by system packages (like APT, scripts in /usr/bin, or Kali dependencies)
    • Controlled via update-alternatives
    • Can be Python 3.11 (or any other preferred default)

  2. pyenv Python (User-Managed)

    • Installs Python versions under ~/.pyenv/versions/
    • Allows switching between multiple Python versions per project or globally
    • Uses shims (~/.pyenv/shims/) to redirect python to the right version
    • Overrides system Python when active

How They Coexist

  • When pyenv is inactive, the system uses the Python version set by update-alternatives (e.g., /usr/bin/python3.11).
  • When pyenv is active, it intercepts the python command and runs its own managed Python versions from ~/.pyenv/versions/.
  • Pyenv does NOT modify or replace system Python—it just redirects the python command using a shim.

How to Make Them Work Together

1. Set Python 3.11 as System Default (For System-Wide Use)

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sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.11 4 sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.11 4 sudo update-alternatives --config python sudo update-alternatives --config python3`

This makes sure that, when pyenv is NOT active, Python 3.11 is used.

2. Make Sure Pyenv Works Properly

Make sure pyenv is correctly installed in your shell:

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export PYENV_ROOT="$HOME/.pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init --path)"
eval "$(pyenv init -)"

To persist these settings, add them to ~/.zshrc or ~/.bashrc:

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echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.zshrc 
echo 'export PATH="$PYENV_ROOT/bin:$PATH"' >> ~/.zshrc 
echo 'eval "$(pyenv init --path)"' >> ~/.zshrc 
echo 'eval "$(pyenv init -)"' >> ~/.zshrc source ~/.zshrc

Now, when you activate pyenv, it will take control over Python.

3. Switching Between System Python and Pyenv

Use System Python (Python 3.11 from update-alternatives). To temporarily disable pyenv and use system Python:

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pyenv global system
python -V  # Should return Python 3.11

Use a Pyenv-Managed Python Version To switch to a specific pyenv-managed Python version:

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pyenv install 3.10.6
pyenv global 3.10.6
python -V  # Should return Python 3.10.6

4. To use a project-specific version:

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cd my_project
pyenv local 3.9.0
python -V  # Should return Python 3.9.0

virtualenvwrapper

Installation

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# Make sure you have pip installed.
sudo apt-get install python3-pip

# Installing virtualenvwrapper 
sudo pip3 install virtualenvwrapper

# Open bashrc by –
sudo gedit ~/.bashrc

# After opening it, add the following  lines to it :

export WORKON_HOME=$HOME/.virtualenvs
export PROJECT_HOME=$HOME/Projects
source /usr/share/virtualenvwrapper/virtualenvwrapper.sh

Basic usage

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# Creating a virtual environment with mkvirtualenv
mkvirtualenv nameOfEnvironment

# List exisiting environment in your 
lsvirtualenv -b

# Work on an environment
workon nameOfEnvironment

# Close current environment
deactivate

# Delete virtual environment
rmvirtualenv nameOfEnvironment

# To work on another version of python:
mkvirtualenv -p python3.x venv_name
# You will see something like this: (venv_name)

Backing up virtual environment before removing it:

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pip freeze > requirements.txt

venv

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python3 -m venv <DIR>
source <DIR>/bin/activate

Now you can activate or deactivate the virtual environment with:

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<DIR>\Scripts\activate

pyenv

Install prerequisites: Ensure you have the required dependencies for pyenv installation.

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sudo apt update sudo apt install -y build-essential libssl-dev zlib1g-dev libbz2-dev \ libreadline-dev libsqlite3-dev wget curl llvm libncurses5-dev libncursesw5-dev \ xz-utils tk-dev libffi-dev liblzma-dev python3-openssl git

Install pyenv: Use the following commands to install pyenv:

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curl https://pyenv.run | bash

Update .bashrc to set up pyenv: Add the following to your .bashrc (or .zshrc if using zsh):

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export PATH="$HOME/.pyenv/bin:$PATH"
eval "$(pyenv init --path)"
eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

Then, reload your shell configuration:

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pyenv install 2.7.18

This command installs Python 2.7.18, or you can choose another Python 2.7 version if needed.

Create a Python 2.7 virtual environment: Once Python 2.7 is installed, you can create a virtual environment with:

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pyenv virtualenv 2.7.18 env_name

Activate the virtual environment: To activate the environment, run:

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pyenv activate env_name

Or deactivate:

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deactivate
Last update: 2025-02-23
Created: February 29, 2024 15:15:09