How to Create a Python Virtual Environment

How to Create a Python Virtual Environment

When you’re building tools, scripts, or testing code, especially for security work, you don’t want your global Python install getting bloated or conflicting with random libraries. That’s where Python virtual environments come in.

A virtual environment gives you a clean, isolated sandbox for your Python project. Different versions of packages, dependencies, tools and no conflicts with your system Python. You can have multiple environments on the same machine each with their own dependencies.

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1. Check Python is installed

Most systems already have Python 3 installed. To check:

python3 --version

If you see something like Python 3.x.x, you’re good. If not, install it using your system package manager.

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2. Install venv (if needed)

In most modern Python installs, venv comes bundled. But if you’re missing it:

sudo apt install python3-venv

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3. Create your virtual environment

Navigate to your project folder or create one:

mkdir myproject cd myproject

Now create the venv:

python3 -m venv venv

This will create a folder called venv inside your project. You can call it whatever you want (env, .venv, etc), but venv is common.

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4. Activate the virtual environment

On Linux/macOS:

source venv/bin/activate

On Windows:

venv\Scripts\activate

Once activated, your shell prompt will show (venv) to indicate you’re inside the environment.

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5. Install packages inside your venv

Now you can safely install packages without touching system Python:

pip install requests

Everything stays local to your venv.

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6. Deactivate when you’re done

deactivate

This drops you back into your system Python.

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7. Bonus tip — freeze your packages

You can snapshot your environment to a requirements.txt file:

pip freeze > requirements.txt

Later you can recreate the same environment:

pip install -r requirements.txt

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Why use venv?

• Keeps your system clean
• Avoids package version conflicts
• Lets you build project-specific environments
• Essential for pen-testing tool development, automation scripts, and bug bounty work

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