A virtual environment can isolate dependencies from different projects. Created using Python's own venv module, with the command python -m venv env; activation method: Windows uses env\Scripts\activate, macOS/Linux uses source env/bin/activate; installation package uses pip install, use pip freeze > requirements.txt to generate requirements files, and use pip install -r requirements.txt to restore the environment; precautions include not submitting to Git, reactivate each time the new terminal is opened, and automatic identification and switching can be used by the IDE.
When using Python for development, you often encounter situations where different projects rely on different version libraries. At this time, it is the turn of Virtual Environment to play. It allows you to create an independent environment for each project without interfering with each other.

What is a virtual environment?
Simply put, the virtual environment is an isolated "small space" with its own set of Python interpreters and installation packages. Global packages in the main system will not affect these environments. This way you can run multiple projects on the same machine, each using its own dependency version, without worrying about conflicts.

For example: Project A requires Django 3.x, while Project B must use Django 4.x. If there is no virtual environment, you can only install one version globally, which may be a waste of time. With a virtual environment, the two projects can be developed in parallel without affecting each other.
How to create a virtual environment?
Python comes with a module called venv
, which is used to create a virtual environment without additional installation.

The basic steps are as follows:
- Open the terminal in the project directory
- Enter the command:
python -m venv env
This will create a new folder calledenv
in the current directory, which is your virtual environment. - Once the creation is complete, the next step is to activate it
Activation methods vary slightly depending on the operating system:
- Windows:
env\Scripts\activate
- macOS/Linux:
source env/bin/activate
Once activated successfully, the terminal prompt will usually start with (env)
, indicating that you are now in this environment.
Install and manage dependencies
After the environment is activated, the packages installed using pip install
will only appear in the current virtual environment. For example, if you want to install requests:
pip install requests
You can view installed packages in the current environment through pip list
.
If you need to migrate or backup dependencies, you can use the following command to generate the requirements file:
pip freeze > requirements.txt
After someone else gets this file, just execute:
pip install -r requirements.txt
You can restore the same environment.
Some precautions for virtual environments
Although the virtual environment is very convenient, there are several small points that are easy to ignore:
- Do not submit the virtual environment to the Git repository. Generally, add
/env/
or the folder name you gave it.gitignore
. - Every time a new terminal window is opened, the virtual environment must be reactivated.
- If you change your computer or reinstall the system, remember to use
requirements.txt
to restore the dependencies. - Some IDEs (such as PyCharm, VS Code) can automatically identify and help you switch virtual environments, eliminating manual operations.
Basically that's it. Making good use of virtual environment can help you avoid many dependency conflicts and make the project structure clearer.
The above is the detailed content of Setting Up and Using Python Virtual Environments. For more information, please follow other related articles on the PHP Chinese website!

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A virtual environment can isolate the dependencies of different projects. Created using Python's own venv module, the command is python-mvenvenv; activation method: Windows uses env\Scripts\activate, macOS/Linux uses sourceenv/bin/activate; installation package uses pipinstall, use pipfreeze>requirements.txt to generate requirements files, and use pipinstall-rrequirements.txt to restore the environment; precautions include not submitting to Git, reactivate each time the new terminal is opened, and automatic identification and switching can be used by IDE.
