[Python] Using ‘venv’: Efficiently Manage Multiple Projects Without Conflicts

What is venv?

Venv is one of Python’s standard libraries that can be used to create virtual environments, providing separate package or module environments. It allows you to manage different versions of packages for each project in isolated environments.

Advantages of venv

• Isolated Environment: Allows you to work on various projects without conflicts between different packages or Python versions.
• Version Management: Easily manage the necessary packages and their versions for each project.
• Dependency Issues Resolution: Clear understanding of each project’s dependencies minimizes problems during deployment or collaboration.

Disadvantages of venv

• Additional Space: Each virtual environment duplicates packages, requiring extra disk space.
• Management: Managing multiple virtual environments can become complex.

How to Use venv

• Creating a Virtual Environment
  Windows: python -m venv [virtual_environment_name]
  Linux/Mac: python3 -m venv [virtual_environment_name]
• Activating the Virtual Environment
  Windows: [virtual_environment_name]\Scripts\activate
  Linux/Mac: source [virtual_environment_name]/bin/activate
• Deactivating the Virtual Environment
  All operating systems: deactivate
• Installing Packages
  In the activated virtual environment,
  use the pip install [package_name] command to install packages.
• Using requirements.txt to Install Packages
  To install all packages listed in requirements.txt at once,
  use the pip install -r requirements.txt command.
• Checking the Package List
  Check the package list in the virtual environment: pip freeze
• Creating requirements.txt in the Virtual Environment
  pip freeze > requirements.txt
• Deleting a Virtual Environment
  Since a virtual environment is stored as a folder, deleting the folder will also delete the virtual environment.

Example Usage

Creating and Activating a Virtual Environment

# Windows
python -m venv myenv
myenv\Scripts\activate

# Linux/Mac
python3 -m venv myenv
source myenv/bin/activate

Installing and Checking Packages

pip install requests
pip freeze

Exiting the Virtual Environment

deactivate

Additional Tip

Solving Virtual Environment Activation Issues in PowerShell

# Windows
myenv\Scripts\activate.ps1

When virtual environment activation fails due to a security error

+ .\Scripts\Activate.ps1
+ ~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : SecurityError: (:) [], PSSecurityException
+ FullyQualifiedErrorId : UnauthorizedAccess

If the above message appears and you cannot enter the virtual environment, it means the Windows execution policy is blocked.

Set-ExecutionPolicy -ExecutionPolicy Unrestricted -Scope LocalMachine

By entering the above command in the cmd window, you can confirm that the virtual environment is activated.