Virtual Environments for Python

Sometimes we want a new, clean environment for testing python codes, and we want the host environment not been interfered with. Using virtual environments could meet the requirements.

This page is for quick startup, it is recommend to read the Official Documentation first, especially the Note part, which contains some explanations for venv.

Creating New Venv

Start from Python 3.6, the build in venv has replaced pyvenv.

Run command:

python3 -m venv /path/to/new/virtual/environment

for generate a new virtual environment.

Activate and Deactivate

For bash/zsh:

source /path/to/new/virtual/environment/bin/activate

Other systems could be found at Official Documentation. Meanwhile,

You can deactivate a virtual environment by typing “deactivate” in your shell.

then the virtual environment has been deactivated and return to the host environment.

Miscellaneous

first-time start

It seems some systems build-in Python will bootstrap pip with old version and provide no wheel as well.

use

pip install pip -U
pip install wheel

to update pip version and install wheel.

Notice that the source of pip in virtual environment is the same as the host environment. If the installation step takes too much time on downloading, consider change another PyPI mirror station.

remove venv

Just remove directory /path/to/new/virtual/environment, painless once and this venv is gone for good. Remember to backup needed files first.

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