NAME

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virtualenv is a tool to create isolated Python environments. Since Python 3.3, a subset of it has been integrated into the standard library under the venv module. For how virtualenv compares to the stdlib venv module, see Explanation.

QUICK NAVIGATION

Tutorials - Learn by doing

•: Getting started — Create your first virtual environment and learn the basic workflow

How-to guides - Solve specific problems

Install virtualenv — Install virtualenv on your system
Use virtualenv — Select Python versions, activate environments, configure defaults, and use from Python code

Reference - Technical information

Compatibility — Supported Python versions and operating systems
Command line — Command line options and flags
Python — Programmatic Python API reference

Explanation - Understand the concepts

•: Explanation — How virtualenv works under the hood and why it exists

Extensions

•: Plugins — Extend virtualenv with custom creators, seeders, and activators

RELATED PROJECTS

Several tools build on virtualenv to provide higher-level workflows:

virtualenvwrapper — Shell wrapper for creating and managing multiple virtualenvs
pew — Python Env Wrapper, a set of commands to manage multiple virtual environments
tox — Automate testing across multiple Python versions
nox — Flexible test automation in Python

EXTERNAL RESOURCES

Learn more about virtualenv from these community resources:

Corey Schafer’s virtualenv tutorial — Video walkthrough for beginners
Bernat Gabor’s status quo — Talk about the current state of Python packaging
Carl Meyer’s reverse-engineering — Deep dive into how virtualenv works internally

Getting started

This tutorial will teach you the basics of virtualenv through hands-on practice. You’ll create your first virtual environment, install packages, and learn how to manage project dependencies.

Prerequisites

Before starting this tutorial, you need:

Python 3.8 or later installed on your system. If you use a version manager like pyenv, mise, or asdf, virtualenv will automatically discover the Python version they manage.
virtualenv installed (see Install virtualenv).

Create your first virtual environment

Let’s create a virtual environment called myproject:

$ virtualenv myproject
created virtual environment CPython3.13.2.final.0-64 in 200ms


  creator CPython3Posix(dest=/home/user/myproject, clear=False, no_vcs_ignore=False, global=False)


  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, via=copy, app_data_dir=/home/user/.cache/virtualenv)


  activators BashActivator,CShellActivator,FishActivator,NushellActivator,PowerShellActivator,PythonActivator

This creates a new directory called myproject containing a complete, isolated Python environment with its own copy of Python, pip, and other tools.

Activate the environment

To use your virtual environment, you can activate it. The activation command differs by platform: [Linux/macOS]

$ source myproject/bin/activate

[Windows (PowerShell)]

PS> .\myproject\Scripts\Activate.ps1

[Windows (CMD)]

C:\> .\myproject\Scripts\activate.bat

After activation, your prompt changes to show the active environment:

(myproject) $

You can verify that Python is now running from inside the virtual environment: [Linux/macOS]

(myproject) $ which python
/home/user/myproject/bin/python

[Windows (PowerShell)]

(myproject) PS> where.exe python
C:\Users\user\myproject\Scripts\python.exe

[Windows (CMD)]

(myproject) C:\> where.exe python
C:\Users\user\myproject\Scripts\python.exe

Install a package

With the environment activated, install a package using pip:

(myproject) $ pip install requests
Collecting requests


  Using cached requests-2.32.3-py3-none-any.whl (64 kB)
Installing collected packages: requests
Successfully installed requests-2.32.3

Verify that the package is installed only inside your virtual environment:

(myproject) $ python -c "import requests; print(requests.__file__)"
/home/user/myproject/lib/python3.13/site-packages/requests/__init__.py

The path shows that requests is installed in the virtual environment, not in your system Python.

Deactivate

When you’re done working in the virtual environment, deactivate it:

(myproject) $ deactivate
$

The prompt returns to normal, and Python commands now use your system Python again.

Use without activation

Activation is a convenience, not a requirement. You can run any executable from the virtual environment directly by using its full path: [Linux/macOS]

$ myproject/bin/python -c "import sys; print(sys.prefix)"
/home/user/myproject
$ myproject/bin/pip install httpx

[Windows (PowerShell)]

PS> .\myproject\Scripts\python.exe -c "import sys; print(sys.prefix)"
C:\Users\user\myproject
PS> .\myproject\Scripts\pip.exe install httpx

[Windows (CMD)]

C:\> .\myproject\Scripts\python.exe -c "import sys; print(sys.prefix)"
C:\Users\user\myproject
C:\> .\myproject\Scripts\pip.exe install httpx

This is especially useful in scripts, CI pipelines, and automation where modifying the shell environment is unnecessary.

Set up a real project

Now let’s apply what you’ve learned to a real project workflow:

$ mkdir myapp && cd myapp
$ virtualenv venv
$ source venv/bin/activate  # or use the appropriate command for your platform
(venv) $ pip install flask requests
(venv) $ pip freeze > requirements.txt

The requirements.txt file now contains your project’s dependencies:

blinker==1.9.0
certifi==2025.1.31
charset-normalizer==3.4.1
click==8.1.8
flask==3.1.0
idna==3.10
itsdangerous==2.2.0
Jinja2==3.1.5
MarkupSafe==3.0.2
requests==2.32.3
urllib3==2.3.0
werkzeug==3.1.3

This file lets you recreate the exact environment later. Let’s test this:

(venv) $ deactivate
$ rm -rf venv
$ virtualenv venv
$ source venv/bin/activate
(venv) $ pip install -r requirements.txt

All packages are reinstalled exactly as before. Here’s the complete workflow: [graph].SS What you learned

In this tutorial, you learned how to:

Create a virtual environment with virtualenv.
Activate and deactivate virtual environments on different platforms.
Install packages in isolation from your system Python.
Save project dependencies with pip freeze.
Reproduce environments using requirements.txt.

Next steps

Now that you understand the basics, explore these topics:

Use virtualenv for selecting specific Python versions, configuring defaults, and advanced usage patterns.
Explanation for understanding how virtualenv works under the hood and how it compares to venv.
Command line for all available command line options and flags.

Install virtualenv

virtualenv is a command-line tool, so it should be installed in an isolated environment rather than into your system Python. Pick the method that fits your setup:

uv – fast, modern Python package manager. Use this if you already have uv or are starting fresh.
pipx – installs Python CLI tools in isolated environments. Use this if you already have pipx set up.
pip – the standard Python package installer. Use --user to avoid modifying system packages. May not work on distributions with externally-managed Python environments.
zipapp – a self-contained executable requiring no installation. Use this in CI or environments where you cannot install packages.

[graph][uv] Install virtualenv as a uv tool:

$ uv tool install virtualenv

Install the development version:

$ uv tool install git+https://github.com/pypa/virtualenv.git@main

[pipx] Install virtualenv using pipx:

$ pipx install virtualenv

Install the development version:

$ pipx install git+https://github.com/pypa/virtualenv.git@main

[pip] Install virtualenv using pip:

$ python -m pip install --user virtualenv

Install the development version:

$ python -m pip install git+https://github.com/pypa/virtualenv.git@main

WARNING:

Some Linux distributions use system-managed Python environments. If you encounter errors about externally-managed environments, use uv tool or pipx instead.

[zipapp] Download the zipapp file and run it directly:

$ python virtualenv.pyz --help

Download the latest version from https://bootstrap.pypa.io/virtualenv.pyz or a specific version from https://bootstrap.pypa.io/virtualenv/x.y/virtualenv.pyz.

Verify installation

Check the installed version:

$ virtualenv --version

See Compatibility for supported Python versions.

Use virtualenv

Select a Python version

By default, virtualenv uses the same Python version it runs under. Override this with --python or -p.

Using version specifiers

Specify a Python version by name or version number:

$ virtualenv -p python3.8 venv
$ virtualenv -p 3.10 venv
$ virtualenv -p pypy3 venv
$ virtualenv -p rustpython venv

Using PEP 440 specifiers

Use PEP 440 version specifiers to match Python versions:

$ virtualenv --python ">=3.12" venv
$ virtualenv --python "~=3.11.0" venv
$ virtualenv --python "cpython>=3.10" venv

>=3.12 – any Python 3.12 or later.
~=3.11.0 – compatible release, equivalent to >=3.11.0, <3.12.0 (any 3.11.x patch).
cpython>=3.10 – restrict to CPython implementation, 3.10 or later.

Using free-threading Python

Create an environment with free-threading Python:

$ virtualenv -p 3.13t venv

Targeting a specific CPU architecture

On machines that support multiple architectures — such as Apple Silicon (arm64 + x86_64 via Rosetta) or Windows on ARM — you can request a specific CPU architecture by appending it to the spec string:

$ virtualenv -p cpython3.12-64-arm64 venv
$ virtualenv -p 3.11-64-x86_64 venv

Cross-platform aliases are normalized automatically, so amd64 and x86_64 are treated as equivalent, as are aarch64 and arm64. If omitted, any architecture matches (preserving existing behavior).

Using absolute paths

Specify the full path to a Python interpreter:

$ virtualenv -p /usr/bin/python3.9 venv

Using --try-first-with

Use --try-first-with to provide a hint about which Python to check first. Unlike --python, this is a hint rather than a rule. The interpreter at this path is checked first, but only used if it matches the --python constraint.

$ virtualenv --python ">=3.10" --try-first-with /usr/bin/python3.9 venv

In this example, /usr/bin/python3.9 is checked first but rejected because it does not satisfy the >=3.10 constraint.

Using version managers (pyenv, mise, asdf)

virtualenv automatically resolves shims from pyenv, mise, and asdf to the real Python binary. Set the active Python version using any of the standard mechanisms and virtualenv will discover it:

$ pyenv local 3.12.0
$ virtualenv venv  # uses pyenv's 3.12.0, not the system Python
$ PYENV_VERSION=3.11.0 virtualenv venv  # uses 3.11.0

This also works with mise and asdf:

$ mise use python@3.12
$ virtualenv venv

No additional configuration is required. See Explanation for details on how shim resolution works.

Activate a virtual environment

Activate the environment to modify your shell’s PATH and environment variables. [Bash/Zsh]

$ source venv/bin/activate

[Fish]

$ source venv/bin/activate.fish

[PowerShell]

PS> .\venv\Scripts\Activate.ps1

NOTE:

If you encounter an execution policy error, run Set-ExecutionPolicy RemoteSigned to allow local scripts.

[CMD]

> .\venv\Scripts\activate.bat

[Nushell]

$ overlay use venv/bin/activate.nu

Deactivate the environment

Exit the virtual environment:

$ deactivate

Use without activation

Use the environment without activating it by calling executables with their full paths:

$ venv/bin/python script.py
$ venv/bin/pip install package

Customize prompt

Set a custom prompt prefix:

$ virtualenv --prompt myproject venv

Disable the prompt modification by setting the VIRTUAL_ENV_DISABLE_PROMPT environment variable.

Access the prompt string via the VIRTUAL_ENV_PROMPT environment variable.

Programmatic activation

Activate the environment from within a running Python process using activate_this.py. This modifies sys.path and environment variables in the current process so that subsequent imports resolve from the virtual environment.

import runpy
runpy.run_path("venv/bin/activate_this.py")

A common use case is web applications served by a system-wide WSGI server (such as mod_wsgi or uWSGI) that need to load packages from a virtual environment:

import runpy
from pathlib import Path
runpy.run_path(str(Path("/var/www/myapp/venv/bin/activate_this.py")))
from myapp import create_app  # noqa: E402
application = create_app()

Configure defaults

Use a configuration file to set default options for virtualenv.

Configuration file location

The configuration file is named virtualenv.ini and located in the platformdirs app config directory. Run virtualenv --help to see the exact location for your system.

Override the location with the VIRTUALENV_CONFIG_FILE environment variable.

Configuration format

Derive configuration keys from command-line options by stripping leading - and replacing remaining - with _:

[virtualenv]
python = /opt/python-3.8/bin/python

Multi-value options

Specify multiple values on separate lines:

[virtualenv]
extra_search_dir =


    /path/to/dists


    /path/to/other/dists

Environment variables

Set options using environment variables with the VIRTUALENV_ prefix and uppercase key names:

$ export VIRTUALENV_PYTHON=/opt/python-3.8/bin/python

For multi-value options, separate values with commas or newlines.

Override app-data location

Set the VIRTUALENV_OVERRIDE_APP_DATA environment variable to override the default app-data cache directory location.

Configuration priority

Options are resolved in this order (highest to lowest priority): [graph].SS Control seed packages

Upgrade embedded wheels

Update the embedded wheel files to the latest versions:

$ virtualenv --upgrade-embed-wheels

Provide custom wheels

Use custom wheel files from a local directory:

$ virtualenv --extra-search-dir /path/to/wheels venv

Download latest from PyPI

Download the latest versions of seed packages from PyPI:

$ virtualenv --download venv

Disable periodic updates

Disable automatic periodic updates of seed packages:

$ virtualenv --no-periodic-update venv

For distribution maintainers

Patch the virtualenv.seed.wheels.embed module and set PERIODIC_UPDATE_ON_BY_DEFAULT to False to disable periodic updates by default. See Explanation for implementation details.

Use from Python code

Call virtualenv from Python code using the cli_run function:

from virtualenv import cli_run
cli_run(["venv"])

Pass options as list elements:

cli_run(["-p", "python3.8", "--without-pip", "myenv"])

Use the returned session object to access environment details:

result = cli_run(["venv"])
print(result.creator.dest)  # path to created environment
print(result.creator.exe)  # path to python executable

Use session_via_cli to describe the environment without creating it:

from virtualenv import session_via_cli
session = session_via_cli(["venv"])
# inspect session.creator, session.seeder, session.activators

See Python for complete API documentation.

Compatibility

Supported Python implementations

virtualenv works with the following Python interpreter implementations. Only the latest patch version of each minor version is fully supported; previous patch versions work on a best effort basis.

CPython

3.14 >= python_version >= 3.8

PyPy

3.11 >= python_version >= 3.8

GraalPy

24.1 and later (Linux and macOS only).

RustPython

Experimental support (Linux, macOS, and Windows). RustPython implements Python 3.14.

Support policy

New versions are added close to their release date, typically during the beta phase.
Old versions are dropped 18 months after CPython EOL, giving users plenty of time to migrate.

Version support timeline

Major version support changes:

20.27.0 (2024-10-17): dropped support for running under Python 3.7 and earlier.
20.22.0 (2023-04-19): dropped support for creating environments for Python 3.6 and earlier.
20.18.0 (2023-02-06): dropped support for running under Python 3.6 and earlier.

Supported operating systems

CPython is shipped in multiple forms, and each OS repackages it, often applying some customization. The platforms listed below are tested. Unlisted platforms may work but are not explicitly supported. If you encounter issues on unlisted platforms, please open a feature request.

Cross-platform

These Python distributions work on Linux, macOS, and Windows:

Installations from python.org
python-build-standalone builds (used by uv and mise)
Python versions managed by pyenv, mise, or asdf (shims are automatically resolved to the real binary)

Linux

Ubuntu 16.04 and later (both upstream and deadsnakes builds)
Fedora
RHEL and CentOS
OpenSuse
Arch Linux

macOS

Python versions installed via Homebrew (works, but not recommended – Homebrew may upgrade or remove Python versions without warning, breaking existing virtual environments)
Python 3 part of XCode (Python framework builds at /Library/Frameworks/Python3.framework/)

NOTE:

Framework builds do not support copy-based virtual environments. Use symlink or hardlink creation methods instead.

Windows

•: Windows Store Python 3.8 and later

Command line

virtualenv is primarily a command line application. All options have sensible defaults, and there is one required argument: the name or path of the virtual environment to create.

See Use virtualenv for how to select Python versions, configure defaults, and use environment variables.

Command line options

virtualenv [OPTIONS]

Named Arguments
	'==SUPPRESS=='	display the version of the virtualenv package and its location, then exit
	False	on failure also display the stacktrace internals of virtualenv
	False	use app data folder in read-only mode (write operations will fail with error)
	platform specific application data folder	a data folder used as cache by the virtualenv
	False	start with empty app data folder
	False	trigger a manual update of the embedded wheels

verbosity ⇒ verbosity = verbose - quiet, default INFO, mapping => CRITICAL=0, ERROR=1, WARNING=2, INFO=3, DEBUG=4, NOTSET=5
	2	increase verbosity
	0	decrease verbosity

discovery

core ⇒ options shared across all discovery
	'builtin'	interpreter discovery method; choice of: builtin
	the python executable virtualenv is installed into	interpreter based on what to create environment (path/identifier/version-specifier) - by default use the interpreter where the tool is installed - first found wins. Version specifiers (e.g., >=3.12, ~=3.11.0, ==3.10) are also supported
	[]	try first these interpreters before starting the discovery

creator

core ⇒ options shared across all creator
	builtin if exist, else venv	create environment via; choice of: cpython3-mac-brew, cpython3-mac-framework, cpython3-posix, cpython3-win, graalpy-posix, graalpy-win, pypy3-posix, pypy3-win, rustpython-posix, rustpython-win, venv
		directory to create virtualenv at
	False	remove the destination directory if exist before starting (will overwrite files otherwise)
	False	don't create VCS ignore directive in the destination directory
	False	give the virtual environment access to the system site-packages dir
	True	try to use symlinks rather than copies, when symlinks are not the default for the platform
	False	try to use copies rather than symlinks, even when symlinks are the default for the platform

seeder

core ⇒ options shared across all seeder
	'app-data'	seed packages install method; choice of: app-data, pip
	False	do not install seed packages
	True	pass to disable download of the latest pip/setuptools/wheel from PyPI
	False	pass to enable download of the latest pip/setuptools/wheel from PyPI
	[]	a path containing wheels to extend the internal wheel list (can be set 1+ times)
	'bundle'	version of pip to install as seed: embed, bundle, none or exact version
	'bundle'	version of setuptools to install as seed: embed, bundle, none or exact version
	False	do not install pip
	False	do not install setuptools
	False	disable the periodic (once every 14 days) update of the embedded wheels

app-data ⇒ options specific to seeder app-data
	False	symlink the python packages from the app-data folder (requires seed pip>=19.3)

activators

core ⇒ options shared across all activators
	comma separated list of activators supported	activators to generate - default is all supported; choice of: bash, batch, cshell, fish, nushell, powershell, python
		provides an alternative prompt prefix for this environment (value of . means name of the current working directory)

Python

The primary interface to virtualenv is the command line application. However, it can also be used programmatically via the virtualenv.cli_run function and the Session class.

See Use virtualenv for usage examples.

virtualenv module

virtualenv.cli_run(args, options=None, setup_logging=True, env=None): Create a virtual environment given some command line interface arguments.

Parameters

args (list[str]) -- the command line arguments
options (Optional[VirtualEnvOptions]) -- passing in a VirtualEnvOptions object allows return of the parsed options
setup_logging (bool) -- True if setup logging handlers, False to use handlers already registered
env (Optional[MutableMapping[str, str]]) -- environment variables to use

Return type: Session
Returns: the session object of the creation (its structure for now is experimental and might change on short notice)

virtualenv.session_via_cli(args, options=None, setup_logging=True, env=None): Create a virtualenv session (same as cli_run, but this does not perform the creation). Use this if you just want to query what the virtual environment would look like, but not actually create it.

Parameters

args (list[str]) -- the command line arguments
options (Optional[VirtualEnvOptions]) -- passing in a VirtualEnvOptions object allows return of the parsed options
setup_logging (bool) -- True if setup logging handlers, False to use handlers already registered
env (Optional[MutableMapping[str, str]]) -- environment variables to use

Return type: Session
Returns: the session object of the creation (its structure for now is experimental and might change on short notice)

Session class

The Session class represents a virtualenv creation session and provides access to the created environment's properties.

class virtualenv.run.session.Session(verbosity, app_data, interpreter, creator, seeder, activators): Represents a virtual environment creation session.

Parameters

verbosity (int) --
app_data (AppData) --
interpreter (PythonInfo) --
creator (Creator) --
seeder (Seeder) --
activators (list[Activator]) --

property verbosity: int: The verbosity of the run.

property interpreter: PythonInfo: Create a virtual environment based on this reference interpreter.

property creator: Creator: The creator used to build the virtual environment (must be compatible with the interpreter).

property seeder: Seeder: The mechanism used to provide the seed packages (pip, setuptools, wheel).

property activators: list[virtualenv.activation.activator.Activator]: Activators used to generate activations scripts.

VirtualEnvOptions

Options namespace passed to plugin constructors, populated from the CLI, environment variables, and configuration files.

class virtualenv.config.cli.parser.VirtualEnvOptions(**kwargs)

Parameters: kwargs (Any) --

set_src(key, value, src): Set an option value and record where it came from.

Parameters

key (str) -- the option name
value (Any) -- the option value
src (str) -- the source of the value (e.g. "cli", "env var", "default")

Return type: None

get_source(key): Return the source that provided a given option value.

Parameters: key (str) -- the option name
Return type: Optional[str]
Returns: the source string (e.g. "cli", "env var", "default"), or None if not tracked

property verbosity: int | None: The verbosity level, computed as verbose - quiet, clamped to zero.

Returns: the verbosity level, or None if neither --verbose nor --quiet has been parsed yet

Explanation

This page explains the design decisions and concepts behind virtualenv. It focuses on understanding why things work the way they do.

virtualenv vs venv vs uv

Since Python 3.3, the standard library includes the venv module, which provides basic virtual environment creation following PEP 405. uv is a newer, Rust-based tool that also creates virtual environments via uv venv.

virtualenv occupies a middle ground: faster and more featureful than venv, while remaining a pure Python solution with a plugin system for extensibility.

	venv	virtualenv	uv
Performance	Slowest (60s+); spawns pip as a subprocess to seed.	Fast; caches pre-built install images, subsequent creation < 1 second.	Fastest; Rust implementation, milliseconds. Does not seed pip/setuptools by default.
Extensibility	No plugin system.	Plugin system for discovery, creation, seeding, and activation.	No plugin system.
Cross-version	Only the Python version it runs under.	Any installed Python via auto-discovery (registry, uv-managed, PATH).	Any installed or uv-managed Python.
Upgradeability	Tied to Python releases.	Independent via PyPI.	Independent via its own release cycle.
Programmatic API	Basic create() function only.	Full Python API; can describe environments without creating them. Used by tox, poetry, pipx, etc.	Command line only.
Type annotations	No py.typed marker; limited annotations.	Fully typed with PEP 561 py.typed marker; checked by ty.	Not applicable (Rust binary).
Best for	Zero dependencies, basic needs.	Plugin extensibility, programmatic API, tool compatibility (tox, virtualenvwrapper).	Maximum speed, already using uv for package management.

[graph].SS How virtualenv works

Python packaging often faces a fundamental problem: different applications require different versions of the same library. If Application A needs requests==2.25.1 but Application B needs requests==2.28.0, installing both into the global site-packages directory creates a conflict. Only one version can exist in a given location.

virtualenv solves this by creating isolated Python environments. Each environment has its own installation directories and can maintain its own set of installed packages, independent of other environments and the system Python.

virtualenv operates in two distinct phases: [graph].INDENT 0.0

Phase 1: Discover a Python interpreter: virtualenv first identifies which Python interpreter to use as the template for the virtual environment. By default, it uses the same Python version that virtualenv itself is running on. You can override this with the --python flag to specify a different interpreter.
Phase 2: Create the virtual environment: Once the target interpreter is identified, virtualenv creates the environment in four steps:

1.: Create a Python executable matching the target interpreter
2.: Install seed packages (pip, setuptools, wheel) to enable package installation
3.: Install activation scripts for various shells
4.: Create VCS ignore files (currently Git’s .gitignore, skip with --no-vcs-ignore)

An important design principle: virtual environments are not self-contained. A complete Python installation consists of thousands of files, and copying all of them into every virtual environment would be wasteful. Instead, virtual environments are lightweight shells that borrow most content from the system Python. They contain only what’s needed to redirect Python’s behavior.

This design has two implications:

Environment creation is fast because only a small number of files need to be created.
Upgrading the system Python might affect existing virtual environments, since they reference the system Python’s standard library and binary extensions.

The Python executable in a virtual environment is effectively isolated from the one used to create it, but the supporting files are shared.

WARNING:

If you upgrade your system Python, existing virtual environments will still report the old version (the version number is embedded in the Python executable itself), but they will use the new version’s standard library and binary extensions. This normally works without issues, but be aware that the environment is effectively running a hybrid of old and new Python versions.

Python discovery

Before creating a virtual environment, virtualenv must locate a Python interpreter. The interpreter determines the virtual environment’s Python version, implementation (CPython, PyPy, etc.), and architecture (32-bit or 64-bit).

The --python flag accepts several specifier formats:

Path specifier: An absolute or relative path to a Python executable, such as /usr/bin/python3.8 or ./python.
Version specifier: A string following the format {implementation}{version}{architecture}{machine} where:

Implementation is alphabetic characters (python means any implementation; if omitted, defaults to python).
Version is dot-separated numbers, optionally followed by t for free-threading builds.
Architecture is -64 or -32 (if omitted, means any architecture).
Machine is the CPU instruction set architecture, e.g. -arm64, -x86_64, -aarch64 (if omitted, means any machine). Cross-platform aliases are normalized automatically (amd64 ↔ x86_64, aarch64 ↔ arm64).

Examples:

python3.8.1 - Any Python implementation with version 3.8.1
3 - Any Python implementation with major version 3
3.13t - Any Python implementation version 3.13 with free-threading enabled
cpython3 - CPython implementation with major version 3
pypy2 - PyPy implementation with major version 2
cpython3.12-64-arm64 - CPython 3.12, 64-bit, ARM64 architecture
3.11-64-x86_64 - Any implementation, version 3.11, 64-bit, x86_64 architecture
rustpython - RustPython implementation

PEP 440 version specifier: Version constraints using PEP 440 operators:

>=3.12 - Any Python 3.12 or later
~=3.11.0 - Compatible with Python 3.11.0
cpython>=3.10 - CPython 3.10 or later

When you provide a specifier, virtualenv searches for matching interpreters using this strategy: [graph].INDENT 0.0

1.: Windows Registry (Windows only): Check registered Python installations per PEP 514.
2.: uv-managed installations: Check the UV_PYTHON_INSTALL_DIR environment variable or platform-specific uv Python directories for managed Python installations.
3.: PATH search: Search for executables on the PATH environment variable with names matching the specification.

Version manager shim resolution

Version managers like pyenv, mise, and asdf place lightweight shim scripts on PATH that delegate to the real Python binary. When virtualenv discovers a Python interpreter by running it as a subprocess, shims may resolve to the wrong Python version (typically the system Python) because the shim’s resolution logic depends on shell environment state that doesn’t fully propagate to child processes.

virtualenv detects shims by checking whether the candidate executable lives in a known shim directory ($PYENV_ROOT/shims, $MISE_DATA_DIR/shims, or $ASDF_DATA_DIR/shims). When a shim is detected, virtualenv bypasses it and locates the real binary directly under the version manager’s versions directory, using the active version from:

1.: The PYENV_VERSION environment variable (colon-separated for multiple versions).
2.: A .python-version file in the current directory or any parent directory.
3.: The global version file at $PYENV_ROOT/version.

This convention is shared across pyenv, mise, and asdf, so the same resolution logic works for all three.

WARNING:

Virtual environments typically reference the system Python’s standard library. If you upgrade the system Python, the virtual environment will report the old version (embedded in its Python executable) but will actually use the new version’s standard library content. This can cause confusion when debugging version-specific behavior.

If you use a virtual environment’s Python as the target for creating another virtual environment, virtualenv will detect the system Python version and create an environment matching the actual (upgraded) version, not the version reported by the virtual environment.

Creators

Creators are responsible for constructing the virtual environment structure. virtualenv supports two types of creators:

venv creator: This creator delegates the entire creation process to the standard library’s venv module, following PEP 405. The venv creator has two limitations:

It only works with Python 3.5 or later.
It requires spawning a subprocess to invoke the venv module, unless virtualenv is installed in the system Python.

The subprocess overhead can be significant, especially on Windows where process creation is expensive.

builtin creator: This creator means virtualenv performs the creation itself by knowing exactly which files to create and which system files to reference. The builtin creator is actually a family of specialized creators for different combinations of Python implementation (CPython, PyPy, GraalPy, RustPython) and platform (Windows, POSIX). The name builtin is an alias that selects the first available builtin creator for the target environment.
Because builtin creators don’t require subprocess invocation, they’re generally faster than the venv creator.

[graph]

virtualenv defaults to using the builtin creator if one is available for the target environment, falling back to the venv creator otherwise.

Seeders

After creating the virtual environment structure, virtualenv installs seed packages that enable package management within the environment. The seed packages are:

pip - The package installer for Python (always installed).
setuptools - Package development and installation library (disabled by default on Python 3.12+).
wheel - Support for the wheel binary package format (only installed by default on Python 3.8).

virtualenv supports two seeding methods with dramatically different performance characteristics:

pip seeder

This method uses the bundled pip wheel to install seed packages by spawning a child pip process. The subprocess performs a full installation, including unpacking wheels and generating metadata. This method is reliable but slow, typically consuming 98% of the total virtual environment creation time.

app-data seeder

This method creates reusable install images in a user application data directory. The first time you create an environment with specific seed package versions, the app-data seeder builds complete install images and stores them in the cache. Subsequent environment creations simply link or copy these pre-built images into the virtual environment’s site-packages directory.

Performance comparison for creating virtual environments: [graph]

On platforms that support symlinks efficiently (Linux, macOS), the app-data seeder provides nearly instant seeding.

You can override the cache location using the VIRTUALENV_OVERRIDE_APP_DATA environment variable.

Wheel acquisition

Both seeding methods require wheel files for the seed packages. virtualenv acquires wheels using a priority system: [graph].INDENT 0.0

Embedded wheels: virtualenv ships with a set of wheels bundled directly into the package. These are tested with the virtualenv release and provide a baseline set of seed packages. Different Python versions require different package versions, so virtualenv bundles multiple wheels to support its wide Python version range.
Upgraded embedded wheels: Users can manually upgrade the embedded wheels by running virtualenv with the --upgrade-embed-wheels flag. This fetches newer versions of seed packages from PyPI and stores them in the user application data directory. Subsequent virtualenv invocations will use these upgraded wheels instead of the embedded ones.
virtualenv can also perform periodic automatic upgrades (see below).
Extra search directories: Users can specify additional directories containing wheels using the --extra-search-dir flag. This is useful in air-gapped environments or when using custom package builds.
PyPI download: If no suitable wheel is found in the above locations, or if the --download flag is set, virtualenv will use pip to download the latest compatible version from PyPI.

Periodic update mechanism

To keep the seed packages reasonably current without requiring users to manually upgrade virtualenv or run --upgrade-embed-wheels, virtualenv implements a periodic automatic update system: [graph]

The 28-day waiting period protects users from automatically adopting newly released packages that might contain bugs. The 1-hour delay after download ensures continuous integration systems don’t start using different package versions mid-run, which could cause confusing test failures.

You can disable the periodic update mechanism with the --no-periodic-update flag.

Distribution maintainer patching

Operating system distributions and package managers sometimes need to customize which seed package versions virtualenv uses. They want to align virtualenv’s bundled packages with system package versions.

Distributions can patch the virtualenv.seed.wheels.embed module, replacing the get_embed_wheel function with their own implementation that returns distribution-provided wheels. If they want to use virtualenv’s test suite for validation, they should also provide the BUNDLE_FOLDER, BUNDLE_SUPPORT, and MAX variables.

Distributions should also consider patching virtualenv.seed.embed.base_embed.PERIODIC_UPDATE_ON_BY_DEFAULT to False, allowing the system package manager to control seed package updates rather than virtualenv’s periodic update mechanism. Users can still manually request upgrades via --upgrade-embed-wheels, but automatic updates won’t interfere with system-managed packages.

Activators

Activation scripts modify the current shell environment to prioritize the virtual environment’s executables. This is purely a convenience mechanism - you can always use absolute paths to virtual environment executables without activating.

What activation does: [graph].INDENT 0.0

PATH modification: The activation script prepends the virtual environment’s bin directory (Scripts on Windows) to the PATH environment variable. This ensures that when you run python, pip, or other executables, the shell finds the virtual environment’s versions first.
Environment variables: Activation sets several environment variables:

VIRTUAL_ENV - Absolute path to the virtual environment directory.
VIRTUAL_ENV_PROMPT - The prompt prefix (the environment name or custom value from --prompt).
PKG_CONFIG_PATH - Modified to include the virtual environment’s lib/pkgconfig directory.

Prompt modification: By default, activation prepends the environment name to your shell prompt, typically shown as (venv) before the regular prompt. This visual indicator helps you remember which environment is active. You can customize this with the --prompt flag when creating the environment, or disable it entirely by setting the VIRTUAL_ENV_DISABLE_PROMPT environment variable.
Deactivation: Activation scripts also provide a deactivate command that reverses the changes, restoring your original PATH and removing the environment variables and prompt modifications.

virtualenv provides activation scripts for multiple shells:

Bash (activate)
Fish (activate.fish)
Csh/Tcsh (activate.csh)
PowerShell (activate.ps1)
Windows Batch (activate.bat)
Nushell (activate.nu)
Python (activate_this.py) – for programmatic activation from within a running Python process, see Programmatic activation

NOTE:

On Windows 7 and later, PowerShell’s default execution policy is Restricted, which prevents running the activate.ps1 script. You can allow locally-generated scripts to run by changing the execution policy:

Set-ExecutionPolicy RemoteSigned

Since virtualenv generates activate.ps1 locally for each environment, PowerShell considers it a local script rather than a remote one and allows execution under the RemoteSigned policy.

Remember: activation is optional. The following commands are equivalent:

# With activation
source venv/bin/activate
python script.py
deactivate
# Without activation
venv/bin/python script.py

For a deeper dive into how activation works under the hood, see Allison Kaptur’s blog post There’s no magic: virtualenv edition, which explains how virtualenv uses PATH and PYTHONHOME to isolate virtual environments.

Plugins

virtualenv can be extended via plugins using Python entry points. Plugins are automatically discovered from the Python environment where virtualenv is installed, allowing you to customize how virtual environments are created, seeded, and activated.

Extension points

virtualenv provides four extension points through entry point groups:

virtualenv.discovery: Python interpreter discovery plugins. These plugins locate and identify Python interpreters that will be used as the base for creating virtual environments.
virtualenv.create: Virtual environment creator plugins. These plugins handle the actual creation of the virtual environment structure, including copying or symlinking the Python interpreter and standard library.
virtualenv.seed: Seed package installer plugins. These plugins install initial packages (like pip, setuptools, wheel) into newly created virtual environments.
virtualenv.activate: Shell activation script plugins. These plugins generate shell-specific activation scripts that modify the environment to use the virtual environment.

All extension points follow a common pattern: virtualenv discovers registered entry points, builds CLI options from them, and executes the selected implementations during environment creation.

Your first plugin

This tutorial walks through creating a simple discovery plugin that locates Python interpreters managed by pyenv.

Create the package structure

Set up a new Python package with the following structure:

virtualenv-pyenv/
├── pyproject.toml
└── src/


    └── virtualenv_pyenv/


        └── __init__.py

Configure the entry point

In pyproject.toml, declare your plugin as an entry point under the virtualenv.discovery group:

[project]
name = "virtualenv-pyenv"
version = "0.1.0"
dependencies = ["virtualenv>=20"]
[project.entry-points."virtualenv.discovery"]
pyenv = "virtualenv_pyenv:PyEnvDiscovery"
[build-system]
requires = ["setuptools>=61"]
build-backend = "setuptools.build_meta"

Implement the plugin

In src/virtualenv_pyenv/__init__.py, implement the discovery plugin by subclassing Discover:

from __future__ import annotations
import subprocess
from pathlib import Path
from virtualenv.discovery.discover import Discover
from virtualenv.discovery.py_info import PythonInfo
class PyEnvDiscovery(Discover):


    def __init__(self, options):


        super().__init__(options)


        self.python_spec = options.python if options.python else "python"


    @classmethod


    def add_parser_arguments(cls, parser):


        parser.add_argument(


            "--python",


            dest="python",


            metavar="py",


            type=str,


            default=None,


            help="pyenv Python version to use (e.g., 3.11.0)",


        )


    def run(self):


        try:


            result = subprocess.run(


                ["pyenv", "which", "python"],


                capture_output=True,


                text=True,


                check=True,


            )


            python_path = Path(result.stdout.strip())


            return PythonInfo.from_exe(str(python_path))


        except (subprocess.CalledProcessError, FileNotFoundError) as e:


            raise RuntimeError(f"Failed to locate pyenv Python: {e}")

Install the plugin

Install your plugin in development mode alongside virtualenv:

$ pip install -e virtualenv-pyenv/

Verify the plugin

Check that virtualenv recognizes your plugin by running:

$ virtualenv --discovery help

The output should list pyenv as an available discovery mechanism. You can now use it:

$ virtualenv --discovery=pyenv myenv
created virtual environment CPython3.11.0.final.0-64 in 234ms


  creator CPython3Posix(dest=/path/to/myenv, clear=False, no_vcs_ignore=False, global=False)


  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/path)


    added seed packages: pip==23.0, setuptools==65.5.0, wheel==0.38.4


  activators BashActivator,CShellActivator,FishActivator,NushellActivator,PowerShellActivator,PythonActivator

Plugin how-to guides

This page provides task-oriented guides for creating each type of virtualenv plugin.

Create a discovery plugin

Discovery plugins locate Python interpreters. Register your plugin under the virtualenv.discovery entry point group.

Implement the Discover interface:

from virtualenv.discovery.discover import Discover
from virtualenv.discovery.py_info import PythonInfo
class CustomDiscovery(Discover):


    @classmethod


    def add_parser_arguments(cls, parser):


        parser.add_argument("--custom-opt", help="custom discovery option")


    def __init__(self, options):


        super().__init__(options)


        self.custom_opt = options.custom_opt


    def run(self):


        # Locate Python interpreter and return PythonInfo


        python_exe = self._find_python()


        return PythonInfo.from_exe(str(python_exe))


    def _find_python(self):


        # Implementation-specific logic


        pass

[virtualenv.discovery]
custom = your_package.discovery:CustomDiscovery

Create a creator plugin

Creator plugins build the virtual environment structure. Register under virtualenv.create.

Implement the Creator interface:

from virtualenv.create.creator import Creator
class CustomCreator(Creator):


    @classmethod


    def add_parser_arguments(cls, parser, interpreter):


        parser.add_argument("--custom-creator-opt", help="custom creator option")


    def __init__(self, options, interpreter):


        super().__init__(options, interpreter)


        self.custom_opt = options.custom_creator_opt


    def create(self):


        # Create directory structure


        self.bin_dir.mkdir(parents=True, exist_ok=True)


        # Copy or symlink Python executable


        self.install_python()


        # Set up site-packages


        self.install_site_packages()


        # Write pyvenv.cfg


        self.set_pyenv_cfg()

[virtualenv.create]
cpython3-posix = virtualenv.create.via_global_ref.builtin.cpython.cpython3:CPython3Posix
cpython3-win = virtualenv.create.via_global_ref.builtin.cpython.cpython3:CPython3Windows

Create a seeder plugin

Seeder plugins install initial packages into the virtual environment. Register under virtualenv.seed.

Implement the Seeder interface:

from virtualenv.seed.seeder import Seeder
class CustomSeeder(Seeder):


    @classmethod


    def add_parser_arguments(cls, parser, interpreter, app_data):


        parser.add_argument("--custom-seed-opt", help="custom seeder option")


    def __init__(self, options, enabled, app_data):


        super().__init__(options, enabled, app_data)


        self.custom_opt = options.custom_seed_opt


    def run(self, creator):


        # Install packages into creator.bin_dir / creator.script("pip")


        self._install_packages(creator)


    def _install_packages(self, creator):


        # Implementation-specific logic


        pass

[virtualenv.seed]
custom = your_package.seed:CustomSeeder

Create an activator plugin

Activator plugins generate shell activation scripts. Register under virtualenv.activate.

Implement the Activator interface:

from virtualenv.activation.activator import Activator
class CustomShellActivator(Activator):


    def generate(self, creator):


        # Generate activation script content


        script_content = self._render_template(creator)


        # Write to activation directory


        dest = creator.bin_dir / self.script_name


        dest.write_text(script_content)


    def _render_template(self, creator):


        # Return activation script content


        return f"""


        # Custom shell activation script


        export VIRTUAL_ENV="{creator.dest}"


        export PATH="{creator.bin_dir}:$PATH"


        """


    @property


    def script_name(self):


        return "activate.custom"

[virtualenv.activate]
bash = virtualenv.activation.bash:BashActivator
fish = virtualenv.activation.fish:FishActivator
custom = your_package.activation:CustomShellActivator

Package and distribute a plugin

Use pyproject.toml to declare entry points:

[project]
name = "virtualenv-custom-plugin"
version = "1.0.0"
dependencies = ["virtualenv>=20.0.0"]
[project.entry-points."virtualenv.discovery"]
custom = "virtualenv_custom.discovery:CustomDiscovery"
[project.entry-points."virtualenv.create"]
custom-posix = "virtualenv_custom.creator:CustomCreator"
[project.entry-points."virtualenv.seed"]
custom = "virtualenv_custom.seeder:CustomSeeder"
[project.entry-points."virtualenv.activate"]
custom = "virtualenv_custom.activator:CustomActivator"
[build-system]
requires = ["setuptools>=61"]
build-backend = "setuptools.build_meta"

Install your plugin alongside virtualenv:

$ pip install virtualenv-custom-plugin

Or in development mode:

$ pip install -e /path/to/virtualenv-custom-plugin

Test your plugin by creating a virtual environment:

$ virtualenv --discovery=custom --creator=custom-posix --seeder=custom --activators=custom test-env

Plugin API reference

This page documents the interfaces that plugins must implement.

Discovery

Discovery plugins locate Python interpreters for creating virtual environments.

class virtualenv.discovery.discover.Discover(options)

Parameters: options (VirtualEnvOptions) --

classmethod add_parser_arguments(parser)

Parameters: parser (ArgumentParser) --
Return type: None

abstract run()

Return type: Optional[PythonInfo]

property interpreter: python_discovery._py_info.PythonInfo | None

Returns: the interpreter as returned by run(), cached

PythonInfo

Discovery plugins return a PythonInfo object describing the located interpreter.

class virtualenv.discovery.py_info.PythonInfo: Contains information for a Python interpreter.

install_path(key): Return the relative installation path for a given installation scheme key.

Parameters: key (str) -- sysconfig installation scheme key (e.g. "scripts", "purelib").
Return type: str

property version_str: str: The full version as major.minor.micro string (e.g. 3.13.2).

property version_release_str: str: The release version as major.minor string (e.g. 3.13).

property python_name: str: The python executable name as pythonX.Y (e.g. python3.13).

property is_old_virtualenv: bool: True if this interpreter runs inside an old-style virtualenv (has real_prefix).

property is_venv: bool: True if this interpreter runs inside a PEP 405 venv (has base_prefix).

sysconfig_path(key, config_var=None, sep='/'): Return the sysconfig install path for a scheme key, optionally substituting config variables.

Parameters

key (str) -- sysconfig path key (e.g. "purelib", "include").
config_var (Optional[dict[str, str]]) -- replacement mapping for sysconfig variables; when None uses the interpreter's own values.
sep (str) -- path separator to use in the result.

Return type: str

property system_include: str: The path to the system include directory for C headers.

property system_prefix: str: The prefix of the system Python this interpreter is based on.

property system_exec_prefix: str: The exec prefix of the system Python this interpreter is based on.

property machine: str: Return the instruction set architecture (ISA) derived from sysconfig.get_platform().

property spec: str: A specification string identifying this interpreter (e.g. CPython3.13.2-64-arm64).

classmethod clear_cache(cache): Clear all cached interpreter information from cache.

Parameters: cache (PyInfoCache) -- the cache store to clear.
Return type: None

satisfies(spec, *, impl_must_match): Check if a given specification can be satisfied by this python interpreter instance.

Parameters

spec (PythonSpec) -- the specification to check against.
impl_must_match (bool) -- when True, the implementation name must match exactly.

Return type: bool

classmethod current(cache=None): Locate the current host interpreter information.

Parameters: cache (Optional[PyInfoCache]) -- interpreter metadata cache; when None results are not cached.
Return type: PythonInfo

classmethod current_system(cache=None): Locate the current system interpreter information, resolving through any virtualenv layers.

Parameters: cache (Optional[PyInfoCache]) -- interpreter metadata cache; when None results are not cached.
Return type: PythonInfo

to_json(): Serialize this interpreter information to a JSON string.

Return type: str

to_dict(): Convert this interpreter information to a plain dictionary.

Return type: dict[str, object]

classmethod from_exe(exe, cache=None, *, raise_on_error=True, ignore_cache=False, resolve_to_host=True, env=None): Get the python information for a given executable path.

Parameters

exe (str) -- path to the Python executable.
cache (Optional[PyInfoCache]) -- interpreter metadata cache; when None results are not cached.
raise_on_error (bool) -- raise on failure instead of returning None.
ignore_cache (bool) -- bypass the cache and re-query the interpreter.
resolve_to_host (bool) -- resolve through virtualenv layers to the system interpreter.
env (Optional[Mapping[str, str]]) -- environment mapping; defaults to os.environ.

Return type: Optional[PythonInfo]

classmethod from_json(payload): Deserialize interpreter information from a JSON string.

Parameters: payload (str) -- JSON produced by to_json().
Return type: PythonInfo

classmethod from_dict(data): Reconstruct a PythonInfo from a plain dictionary.

Parameters: data (dict[str, object]) -- dictionary produced by to_dict().
Return type: PythonInfo

classmethod resolve_to_system(cache, target): Walk virtualenv/venv prefix chains to find the underlying system interpreter.

Parameters

cache (Optional[PyInfoCache]) -- interpreter metadata cache; when None results are not cached.
target (PythonInfo) -- the interpreter to resolve.

Return type: PythonInfo

discover_exe(cache, prefix, *, exact=True, env=None): Discover a matching Python executable under a given prefix directory.

Parameters

cache (PyInfoCache) -- interpreter metadata cache.
prefix (str) -- directory prefix to search under.
exact (bool) -- when True, require an exact version match.
env (Optional[Mapping[str, str]]) -- environment mapping; defaults to os.environ.

Return type: PythonInfo

App data

The application data interface used by plugins for caching.

class virtualenv.app_data.base.AppData: Abstract storage interface for the virtualenv application.

abstract close(): Called before virtualenv exits.

Return type: None

abstract reset(): Called when the user passes in the reset app data.

Return type: None

abstract py_info(path): Return a content store for cached interpreter information at the given path.

Parameters: path (Path) -- the interpreter executable path
Return type: ContentStore
Returns: a content store for the cached data

abstract py_info_clear(): Clear all cached interpreter information.

Return type: None

property can_update: bool: True if this app data store supports updating cached content.

abstract embed_update_log(distribution, for_py_version): Return a content store for the embed update log of a distribution.

Parameters

distribution (str) -- the package name (e.g. pip)
for_py_version (str) -- the target Python version string

Return type: ContentStore
Returns: a content store for the update log

property house: Path: The root directory of the application data store.

property transient: bool: True if this app data store is transient and does not persist across runs.

abstract wheel_image(for_py_version, name): Return the path to a cached wheel image.

Parameters

for_py_version (str) -- the target Python version string
name (str) -- the package name

Return type: Path
Returns: the path to the cached wheel

ensure_extracted(path, to_folder=None): Ensure a path is available on disk, extracting from zipapp if needed.

Parameters

path (Path) -- the path to ensure is available
to_folder (Optional[Path]) -- optional target directory for extraction

Return type: Generator[Path]
Returns: yields the usable path on disk

abstract extract(path, to_folder): Extract a path from the zipapp to a location on disk.

Parameters

path (Path) -- the path to extract
to_folder (Optional[Path]) -- optional target directory

Return type: Generator[Path]
Returns: yields the extracted path

abstract locked(path): Acquire an exclusive lock on the given path.

Parameters: path (Path) -- the path to lock
Return type: Generator[None]

Creators

Creator plugins build the virtual environment directory structure and install the Python interpreter.

class virtualenv.create.creator.CreatorMeta

class virtualenv.create.creator.Creator(options, interpreter): A class that given a python Interpreter creates a virtual environment.

Parameters

options (VirtualEnvOptions) --
interpreter (PythonInfo) --

Construct a new virtual environment creator.

Parameters

options (VirtualEnvOptions) -- the CLI option as parsed from add_parser_arguments()
interpreter (PythonInfo) -- the interpreter to create virtual environment from

classmethod can_create(interpreter): Determine if we can create a virtual environment.

Parameters: interpreter (PythonInfo) -- the interpreter in question
Return type: Optional[CreatorMeta]
Returns: None if we can't create, any other object otherwise that will be forwarded to add_parser_arguments()

classmethod add_parser_arguments(parser, interpreter, meta, app_data): Add CLI arguments for the creator.

Parameters

parser (ArgumentParser) -- the CLI parser
app_data (AppData) -- the application data folder
interpreter (PythonInfo) -- the interpreter we're asked to create virtual environment for
meta (CreatorMeta) -- value as returned by can_create()

Return type: None

abstract create(): Perform the virtual environment creation.

Return type: None

add_cachedir_tag(): Generate a file indicating that this is not meant to be backed up.

Return type: None

setup_ignore_vcs(): Generate ignore instructions for version control systems.

Return type: None

Seeders

Seeder plugins install initial packages (like pip, setuptools, wheel) into the virtual environment.

class virtualenv.seed.seeder.Seeder(options, enabled): A seeder will install some seed packages into a virtual environment.

Parameters

options (VirtualEnvOptions) --
enabled (bool) --

Create.

Parameters

options (VirtualEnvOptions) -- the parsed options as defined within add_parser_arguments()
enabled (bool) -- a flag weather the seeder is enabled or not

classmethod add_parser_arguments(parser, interpreter, app_data): Add CLI arguments for this seed mechanisms.

Parameters

parser (ArgumentParser) -- the CLI parser
app_data (AppData) -- the CLI parser
interpreter (PythonInfo) -- the interpreter this virtual environment is based of

Return type: None

abstract run(creator): Perform the seed operation.

Parameters: creator (Creator) -- the creator (based of virtualenv.create.creator.Creator) we used to create this virtual environment
Return type: None

Activators

Activator plugins generate shell-specific activation scripts.

class virtualenv.activation.activator.Activator(options): Generates activate script for the virtual environment.

Parameters: options (VirtualEnvOptions) --

Create a new activator generator.

Parameters: options (VirtualEnvOptions) -- the parsed options as defined within add_parser_arguments()

classmethod supports(interpreter): Check if the activation script is supported in the given interpreter.

Parameters: interpreter (PythonInfo) -- the interpreter we need to support
Return type: bool
Returns: True if supported, False otherwise

classmethod add_parser_arguments(parser, interpreter): Add CLI arguments for this activation script.

Parameters

parser (ArgumentParser) -- the CLI parser
interpreter (PythonInfo) -- the interpreter this virtual environment is based of

Return type: None

abstract generate(creator): Generate activate script for the given creator.

Parameters: creator (Creator) -- the creator (based of virtualenv.create.creator.Creator) we used to create this virtual environment
Return type: list[Path]

Plugin architecture

This page explains how virtualenv’s plugin system works internally.

Entry points

virtualenv uses Python entry points (setuptools / importlib.metadata) to discover plugins. Each plugin registers under one of four entry point groups:

virtualenv.discovery
virtualenv.create
virtualenv.seed
virtualenv.activate

At startup, virtualenv loads all registered entry points from these groups and makes them available as CLI options. Built-in implementations are registered in virtualenv’s own pyproject.toml, while third-party plugins register their entry points in their own package metadata.

When a package with virtualenv plugins is installed in the same environment as virtualenv, the plugins become immediately available without additional configuration.

Plugin lifecycle

The following diagram shows how plugins are discovered and executed: [graph]

The lifecycle follows these stages:

1.: virtualenv starts and discovers all entry points from the four plugin groups
2.: The CLI parser is built dynamically, incorporating options from all discovered plugins
3.: User arguments are parsed to select which discovery, creator, seeder, and activator plugins to use
4.: Selected plugins execute in sequence: discover → create → seed → activate
5.: Each stage passes its output to the next stage

Extension point design

Each extension point follows a consistent pattern:

Base abstract class: Each extension point defines a base abstract class (Discover, Creator, Seeder, Activator) that specifies the interface plugins must implement.
Built-in implementations: virtualenv includes built-in implementations registered as entry points in its own pyproject.toml. For example, the built-in CPython creator is registered as cpython3-posix.
Third-party plugins: External packages implement the base interface and register their own entry points under the same group. When installed, they appear alongside built-in options.
CLI selection: Command-line flags (--discovery, --creator, --seeder, --activators) allow users to select which implementation to use. Multiple activators can be selected simultaneously.
Parser integration: Each plugin can contribute CLI arguments through the add_parser_arguments classmethod. These arguments appear in virtualenv --help and are available when the plugin is selected.

How plugins interact

Plugins execute in a pipeline where each stage depends on the previous one:

Discovery → Creator: The discovery plugin produces a PythonInfo object describing the source Python interpreter. This object contains metadata about the Python version, platform, paths, and capabilities. The creator plugin receives this PythonInfo and uses it to determine how to build the virtual environment structure.
Creator → Seeder: The creator plugin produces a Creator object representing the newly created virtual environment. This includes paths to the environment’s bin directory, site-packages, and Python executable. The seeder plugin uses these paths to install packages.
Seeder → Activator: After seeding completes, activator plugins use the Creator object to generate shell activation scripts. These scripts reference the environment’s bin directory and other paths to configure the shell environment.

This pipeline ensures that each plugin has the information it needs from previous stages. The PythonInfo flows from discovery to creator, and the Creator object flows from creator to both seeder and activators.

Plugin isolation

Plugins within the same extension point do not interact with each other. Only one discovery and one creator plugin can run per invocation, though multiple activators can run simultaneously. This isolation keeps plugins simple and focused on their specific task.

Development

Getting started

virtualenv is a volunteer maintained open source project and we welcome contributions of all forms. The sections below will help you get started with development, testing, and documentation. We’re pleased that you are interested in working on virtualenv. This document is meant to get you setup to work on virtualenv and to act as a guide and reference to the development setup. If you face any issues during this process, please open an issue about it on the issue tracker.

Setup

virtualenv is a command line application written in Python. To work on it, you’ll need:

•

Source code: available on GitHub. You can use git to clone the: repository:

git clone https://github.com/pypa/virtualenv
cd virtualenv

Python interpreter: We recommend using CPython. You can use this guide to set it up.
tox: to automatically get the projects development dependencies and run the test suite. We recommend installing it using pipx.

Running from source tree

The easiest way to do this is to generate the development tox environment, and then invoke virtualenv from under the .tox/dev folder

tox -e dev
.tox/dev/bin/virtualenv  # on Linux
.tox/dev/Scripts/virtualenv  # on Windows

Running tests

virtualenv’s tests are written using the pytest test framework. tox is used to automate the setup and execution of virtualenv’s tests.

To run tests locally execute:

tox -e py

This will run the test suite for the same Python version as under which tox is installed. Alternatively you can specify a specific version of python by using the pyNN format, such as: py38, pypy3, etc.

tox has been configured to forward any additional arguments it is given to pytest. This enables the use of pytest’s rich CLI. As an example, you can select tests using the various ways that pytest provides:

# Using markers
tox -e py -- -m "not slow"
# Using keywords
tox -e py -- -k "test_extra"

Some tests require additional dependencies to be run, such is the various shell activators (bash, fish, powershell, etc). These tests will automatically be skipped if these are not present, note however that in CI all tests are run; so even if all tests succeed locally for you, they may still fail in the CI.

Running linters

virtualenv uses pre-commit for managing linting of the codebase. pre-commit performs various checks on all files in virtualenv and uses tools that help follow a consistent code style within the codebase. To use linters locally, run:

tox -e fix

NOTE:

Avoid using # noqa comments to suppress linter warnings - wherever possible, warnings should be fixed instead. # noqa comments are reserved for rare cases where the recommended style causes severe readability problems.

Type checking

virtualenv ships a PEP 561 py.typed marker and has comprehensive type annotations across the entire codebase. This means downstream consumers and type checkers automatically recognize virtualenv as an inline-typed package.

All new code must include complete type annotations for function parameters and return types. To verify annotations locally, run:

tox -e type

This uses ty (Astral’s Rust-based type checker) to validate annotations against Python 3.14. A second environment checks compatibility with the minimum supported version:

tox -e type-3.8

Both environments validate that annotations are consistent and correct.

Annotation guidelines

Use from __future__ import annotations at the top of every module (enforced by ruff’s required-imports setting).
Place imports that are only needed for type checking inside an if TYPE_CHECKING: block to avoid runtime overhead.
Ruff’s ANN rules are enabled. ANN401 (typing.Any) is suppressed on a case-by-case basis with inline # noqa: ANN401 comments where Any is genuinely required (e.g. serialization, dynamic dispatch).
Prefer concrete types over Any. Use Union / | for nullable or multi-type parameters.
When a type error is genuinely unfixable (e.g. third-party library limitations), suppress it with an inline # ty: ignore[rule-name] comment and a brief justification.

Building documentation

virtualenv’s documentation is built using Sphinx. The documentation is written in reStructuredText. To build it locally, run:

tox -e docs

The built documentation can be found in the .tox/docs_out folder and may be viewed by opening index.html within that folder.

Release

virtualenv’s release schedule is tied to pip and setuptools. We bundle the latest version of these libraries so each time there’s a new version of any of these, there will be a new virtualenv release shortly afterwards (we usually wait just a few days to avoid pulling in any broken releases).

Performing a release

A full release publishes to PyPI, creates a GitHub Release with the zipapp attached, and updates get-virtualenv so that https://bootstrap.pypa.io/virtualenv.pyz serves the new version.

Version bumping

The --version argument to tox r -e release controls the version. It defaults to auto, which inspects the docs/changelog directory: if any *.feature.rst or *.removal.rst fragments exist, the minor version is bumped, otherwise the patch version is bumped. You can also pass major, minor, or patch explicitly.

Both methods produce identical results: a release commit and tag on main. Pushing the tag triggers the Release workflow which builds the sdist, wheel, and zipapp, publishes to PyPI via trusted publisher, creates a GitHub Release with the zipapp attached, and updates get-virtualenv. If publish fails, a rollback job automatically reverts everything.

Via GitHub Actions (recommended)

1.: Go to the Pre-release workflow on GitHub.
2.: Click Run workflow and select the bump type (auto, major, minor, or patch).

Locally

tox r -e release

Pass --version <bump> to override the default auto behavior (e.g. --version minor).

Contributing

Submitting pull requests

Submit pull requests against the main branch, providing a good description of what you’re doing and why. You must have legal permission to distribute any code you contribute to virtualenv and it must be available under the MIT License. Provide tests that cover your changes and run the tests locally first. virtualenv supports multiple Python versions and operating systems. Any pull request must consider and work on all these platforms.

Pull Requests should be small to facilitate review. Keep them self-contained, and limited in scope. Studies have shown that review quality falls off as patch size grows. Sometimes this will result in many small PRs to land a single large feature. In particular, pull requests must not be treated as “feature branches”, with ongoing development work happening within the PR. Instead, the feature should be broken up into smaller, independent parts which can be reviewed and merged individually.

Additionally, avoid including “cosmetic” changes to code that is unrelated to your change, as these make reviewing the PR more difficult. Examples include re-flowing text in comments or documentation, or addition or removal of blank lines or whitespace within lines. Such changes can be made separately, as a “formatting cleanup” PR, if needed.

Automated testing

All pull requests and merges to ‘main’ branch are tested using GitHub Actions (configured by .github/workflows/check.yaml file at the root of the repository). You can find the status and results to the CI runs for your PR on GitHub’s Web UI for the pull request. You can also find links to the CI services’ pages for the specific builds in the form of “Details” links, in case the CI run fails and you wish to view the output.

To trigger CI to run again for a pull request, you can close and open the pull request or submit another change to the pull request. If needed, project maintainers can manually trigger a restart of a job/build.

NEWS entries

The changelog.rst file is managed using towncrier and all non trivial changes must be accompanied by a news entry. To add an entry to the news file, first you need to have created an issue describing the change you want to make. A Pull Request itself may function as such, but it is preferred to have a dedicated issue (for example, in case the PR ends up rejected due to code quality reasons).

Once you have an issue or pull request, you take the number and you create a file inside of the docs/changelog directory named after that issue number with an extension of:

feature.rst,
bugfix.rst,
doc.rst,
removal.rst,
misc.rst.

Thus if your issue or PR number is 1234 and this change is fixing a bug, then you would create a file docs/changelog/1234.bugfix.rst. PRs can span multiple categories by creating multiple files (for instance, if you added a feature and deprecated/removed the old feature at the same time, you would create docs/changelog/1234.bugfix.rst and docs/changelog/1234.remove.rst). Likewise if a PR touches multiple issues/PRs you may create a file for each of them with the same contents and towncrier will deduplicate them.

Contents of a NEWS entry

The contents of this file are reStructuredText formatted text that will be used as the content of the news file entry. You do not need to reference the issue or PR numbers here as towncrier will automatically add a reference to all of the affected issues when rendering the news file.

In order to maintain a consistent style in the changelog.rst file, it is preferred to keep the news entry to the point, in sentence case, shorter than 120 characters and in an imperative tone – an entry should complete the sentence This change will …. In rare cases, where one line is not enough, use a summary line in an imperative tone followed by a blank line separating it from a description of the feature/change in one or more paragraphs, each wrapped at 120 characters. Remember that a news entry is meant for end users and should only contain details relevant to an end user.

Choosing the type of NEWS entry

A trivial change is anything that does not warrant an entry in the news file. Some examples are: code refactors that don’t change anything as far as the public is concerned, typo fixes, white space modification, etc. To mark a PR as trivial a contributor simply needs to add a randomly named, empty file to the news/ directory with the extension of .trivial.

Becoming a maintainer

If you want to become an official maintainer, start by helping out. As a first step, we welcome you to triage issues on virtualenv’s issue tracker. virtualenv maintainers provide triage abilities to contributors once they have been around for some time and contributed positively to the project. This is optional and highly recommended for becoming a virtualenv maintainer. Later, when you think you’re ready, get in touch with one of the maintainers and they will initiate a vote among the existing maintainers.

NOTE:

Upon becoming a maintainer, a person should be given access to various virtualenv-related tooling across multiple platforms. These are noted here for future reference by the maintainers:

GitHub Push Access
PyPI Publishing Access
CI Administration capabilities
ReadTheDocs Administration capabilities

Release History

v[UNRELEASED DRAFT] (2026-06-20)

No significant changes.

v21.2.0 (2026-03-09)

Features - 21.2.0

•: Update embed wheel generator (tasks/upgrade_wheels.py) to include type annotations in generated output - by @rahuldevikar. (#3075)

Bugfixes - 21.2.0

Pass --without-scm-ignore-files to subprocess venv on Python 3.13+ so virtualenv controls .gitignore creation, fixing flaky test_create_no_seed and --no-vcs-ignore being ignored in subprocess path - by @gaborbernat. (#3089)
Use BASH_SOURCE[0] instead of $0 in the bash activate script relocation fallback, fixing incorrect PATH when sourcing the activate script from a different directory - by @gaborbernat. (#3090)

v21.1.0 (2026-02-27)

Features - 21.1.0

•: Add comprehensive type annotations across the entire codebase and ship a PEP 561 py.typed marker so downstream consumers and type checkers recognize virtualenv as an inline-typed package - by @rahuldevikar. (#3075)

v21.0.0 (2026-02-25)

Deprecations and Removals - 21.0.0

•: The Python discovery logic has been extracted into a standalone python-discovery package on PyPI (documentation) and is now consumed as a dependency. If you previously imported discovery internals directly (e.g. from virtualenv.discovery.py_info import PythonInfo), switch to from python_discovery import PythonInfo. Backward-compatibility re-export shims are provided at virtualenv.discovery.py_info, virtualenv.discovery.py_spec, and virtualenv.discovery.cached_py_info, however these are considered unsupported and may be removed in a future release - by @gaborbernat. (#3070)

v20.39.1 (2026-02-25)

Features - 20.39.1

•: Add support for creating virtual environments with RustPython - by @elmjag. (#3010)

v20.39.0 (2026-02-23)

Features - 20.39.0

Automatically resolve version manager shims (pyenv, mise, asdf) to the real Python binary during discovery, preventing incorrect interpreter selection when shims are on PATH - by @gaborbernat. (#3049)
Add architecture (ISA) awareness to Python discovery — users can now specify a CPU architecture suffix in the --python spec string (e.g. cpython3.12-64-arm64) to distinguish between interpreters that share the same version and bitness but target different architectures. Uses sysconfig.get_platform() as the data source, with cross-platform normalization (amd64 ↔ x86_64, aarch64 ↔ arm64). Omitting the suffix preserves existing behavior - by @rahuldevikar. (#3059)

v20.38.0 (2026-02-19)

Features - 20.38.0

Store app data (pip/setuptools/wheel caches) under the OS cache directory (platformdirs.user_cache_dir) instead of the data directory (platformdirs.user_data_dir). Existing app data at the old location is automatically migrated on first use. This ensures cached files that can be redownloaded are placed in the standard cache location (e.g. ~/.cache on Linux, ~/Library/Caches on macOS) where they are excluded from backups and can be cleaned by system tools - by @rahuldevikar. (#1884) (#1884)
Add PKG_CONFIG_PATH environment variable support to all activation scripts (Bash, Batch, PowerShell, Fish, C Shell, Nushell, and Python). The virtualenv’s lib/pkgconfig directory is now automatically prepended to PKG_CONFIG_PATH on activation and restored on deactivation, enabling packages that use pkg-config during build/install to find their configuration files - by @rahuldevikar. (#2637)
Upgrade embedded pip to 26.0.1 from 25.3 and setuptools to 82.0.0, 75.3.4 from 75.3.2, 80.9.0 - by @rahuldevikar. (#3027)
Replace ty: ignore comments with proper type narrowing using assertions and explicit None checks - by @rahuldevikar. (#3029)

Bugfixes - 20.38.0

Exclude pywin32 DLLs (pywintypes*.dll, pythoncom*.dll) from being copied to the Scripts directory during virtualenv creation on Windows. This fixes compatibility issues with pywin32, which expects its DLLs to be installed in site-packages/pywin32_system32 by its own post-install script - by @rahuldevikar. (#2662)
Preserve symlinks in pyvenv.cfg paths to match venv behavior. Use os.path.abspath() instead of os.path.realpath() to normalize paths without resolving symlinks, fixing issues with Python installations accessed via symlinked directories (common in network-mounted filesystems) - by @rahuldevikar. Fixes #2770. (#2770)
Fix Windows activation scripts to properly quote python.exe path, preventing failures when Python is installed in a path with spaces (e.g., C:\Program Files) and a file named C:\Program exists on the filesystem - by @rahuldevikar. (#2985)
Fix bash -u (set -o nounset) compatibility in bash activation script by using ${PKG_CONFIG_PATH:-} and ${PKG_CONFIG_PATH:+:${PKG_CONFIG_PATH}} to handle unset PKG_CONFIG_PATH - by @Fridayai700. (#3044)
Gracefully handle corrupted on-disk cache and invalid JSON from Python interrogation subprocess instead of crashing with unhandled JSONDecodeError or KeyError - by @gaborbernat. (#3054)

v20.36.1 (2026-01-09)

Bugfixes - 20.36.1

•: Fix TOCTOU vulnerabilities in app_data and lock directory creation that could be exploited via symlink attacks - reported by @tsigouris007, fixed by @gaborbernat. (#3013)

v20.36.0 (2026-01-07)

Features - 20.36.0

•: Add support for PEP 440 version specifiers in the --python flag. Users can now specify Python versions using operators like >=, <=, ~=, etc. For example: virtualenv --python=">=3.12" myenv . (:issue:`2994)

v20.35.4 (2025-10-28)

Bugfixes - 20.35.4

Fix race condition in _virtualenv.py when file is overwritten during import, preventing NameError when _DISTUTILS_PATCH is accessed - by @gracetyy. (#2969)
Upgrade embedded wheels:

•: pip to 25.3 from 25.2 (#2989)

v20.35.3 (2025-10-10)

Bugfixes - 20.35.3

•: Accept RuntimeError in test_too_many_open_files, by @esafak (#2935)

v20.35.2 (2025-10-10)

Bugfixes - 20.35.2

•: Revert out changes related to the extraction of the discovery module - by @gaborbernat. (#2978)

v20.35.1 (2025-10-09)

Bugfixes - 20.35.1

Patch get_interpreter to handle missing cache and app_data - by @esafak (#2972)
Fix backwards incompatible changes to PythonInfo - by @gaborbernat. (#2975)

v20.35.0 (2025-10-08)

Features - 20.35.0

Add AppData and Cache protocols to discovery for decoupling - by @esafak. (#2074)
Ensure python3.exe and python3 on Windows for Python 3 - by @esafak. (#2774)

Bugfixes - 20.35.0

Replaced direct references to tcl/tk library paths with getattr - by @esafak (#2944)
Restore absolute import of fs_is_case_sensitive - by @esafak. (#2955)

v20.34.0 (2025-08-13)

Features - 20.34.0

Abstract out caching in discovery - by @esafak. Decouple FileCache from py_info (discovery) - by @esafak. Remove references to py_info in FileCache - by @esafak. Decouple discovery from creator plugins - by @esafak. Decouple discovery by duplicating info utils - by @esafak. (#2074)
Add PyPy 3.11 support. Contributed by @esafak. (#2932)

Bugfixes - 20.34.0

Upgrade embedded wheel pip to 25.2 from 25.1.1 - by @gaborbernat. (#2333)
Accept RuntimeError in test_too_many_open_files, by @esafak (#2935)
Python in PATH takes precedence over uv-managed python. Contributed by @edgarrmondragon. (#2952)

v20.33.1 (2025-08-05)

Bugfixes - 20.33.1

Correctly unpack _get_tcl_tk_libs() response in PythonInfo. Contributed by @esafak. (#2930)
Restore py_info.py timestamp in test_py_info_cache_invalidation_on_py_info_change Contributed by @esafak. (#2933)

v20.33.0 (2025-08-03)

Features - 20.33.0

•: Added support for Tcl and Tkinter. You’re welcome. Contributed by @esafak. (#425)

Bugfixes - 20.33.0

Prevent logging setup when –help is passed, fixing a flaky test. Contributed by @esafak. (#u)
Fix cache invalidation for PythonInfo by hashing py_info.py. Contributed by @esafak. (#2467)
When no discovery plugins are found, the application would crash with a StopIteration. This change catches the StopIteration and raises a RuntimeError with a more informative message. Contributed by @esafak. (#2493)
Stop –try-first-with overriding absolute –python paths. Contributed by @esafak. (#2659)
Force UTF-8 encoding for pip download Contributed by @esafak. (#2780)
Creating a virtual environment on a filesystem without symlink-support would fail even with –copies Make fs_supports_symlink perform a real symlink creation check on all platforms. Contributed by @esafak. (#2786)
Add a note to the user guide recommending the use of a specific Python version when creating virtual environments. Contributed by @esafak. (#2808)
Fix ‘Too many open files’ error due to a file descriptor leak in virtualenv’s locking mechanism. Contributed by @esafak. (#2834)
Support renamed Windows venv redirector (venvlauncher.exe and venvwlauncher.exe) on Python 3.13 Contributed by @esafak. (#2851)
Resolve Nushell activation script deprecation warnings by dynamically selecting the --optional flag for Nushell get command on version 0.106.0 and newer, while retaining the deprecated -i flag for older versions to maintain compatibility. Contributed by @gaborbernat. (#2910)

v20.32.0 (2025-07-20)

Features - 20.32.0

Warn on incorrect invocation of Nushell activation script - by @esafak. (#nushell_activation)
Discover uv-managed Python installations (#2901)

Bugfixes - 20.32.0

Ignore missing absolute paths for python discovery - by @esafak (#2870)
Upgrade embedded setuptools to 80.9.0 from 80.3.1 - by @gaborbernat. (#2900)

v20.31.2 (2025-05-08)

No significant changes.

v20.31.1 (2025-05-05)

Bugfixes - 20.31.1

•: Upgrade embedded wheels:

pip to 25.1.1 from 25.1
setuptools to 80.3.1 from 78.1.0 (#2880)

v20.31.0 (2025-05-05)

Features - 20.31.0

•: No longer bundle wheel wheels (except on Python 3.8), setuptools includes native bdist_wheel support. Update pip to 25.1. (#2868)

Bugfixes - 20.31.0

get_embed_wheel() no longer fails with a TypeError when it is called with an unknown distribution. (#2877)
Fix HelpFormatter error with Python 3.14.0b1. (#2878)

v20.30.0 (2025-03-31)

Features - 20.30.0

•: Add support for GraalPy. (#2832)

Bugfixes - 20.30.0

•: Upgrade embedded wheels:

•: setuptools to 78.1.0 from 75.3.2 (#2863)

v20.29.3 (2025-03-06)

Bugfixes - 20.29.3

•: Ignore unreadable directories in PATH. (#2794)

v20.29.2 (2025-02-10)

Bugfixes - 20.29.2

Remove old virtualenv wheel from the source distribution - by @gaborbernat. (#2841)
Upgrade embedded wheel pip to 25.0.1 from 24.3.1 - by @gaborbernat. (#2843)

v20.29.1 (2025-01-17)

Bugfixes - 20.29.1

•: Fix PyInfo cache incompatibility warnings - by @robsdedude. (#2827)

v20.29.0 (2025-01-15)

Features - 20.29.0

•: Add support for selecting free-threaded Python interpreters, e.g., python3.13t. (#2809)

Bugfixes - 20.29.0

•: Upgrade embedded wheels:

•: setuptools to 75.8.0 from 75.6.0 (#2823)

v20.28.1 (2025-01-02)

Bugfixes - 20.28.1

•: Skip tcsh tests on broken tcsh versions - by @gaborbernat. (#2814)

v20.28.0 (2024-11-25)

Features - 20.28.0

•: Write CACHEDIR.TAG file on creation - by “user:neilramsay. (#2803)

v20.27.2 (2024-11-25)

Bugfixes - 20.27.2

•: Upgrade embedded wheels:

•: setuptools to 75.3.0 from 75.2.0 (#2798)

•: Upgrade embedded wheels:

wheel to 0.45.0 from 0.44.0
setuptools to 75.5.0 (#2800)

no longer forcibly echo off during windows batch activation (#2801)
Upgrade embedded wheels:

setuptools to 75.6.0 from 75.5.0
wheel to 0.45.1 from 0.45.0 (#2804)

v20.27.1 (2024-10-28)

Bugfixes - 20.27.1

•: Upgrade embedded wheels:

•: pip to 24.3.1 from 24.2 (#2789)

v20.27.0 (2024-10-17)

Features - 20.27.0

•: Drop 3.7 support as the CI environments no longer allow it running - by @gaborbernat. (#2758)

Bugfixes - 20.27.0

When a $PATH entry cannot be checked for existence, skip it instead of terminating - by @hroncok. (#2782)
Upgrade embedded wheels:

setuptools to 75.2.0 from 75.1.0
Removed pip of 24.0
Removed setuptools of 68.0.0
Removed wheel of 0.42.0
by @gaborbernat. (#2783)

•: Fix zipapp is broken on Windows post distlib 0.3.9 - by @gaborbernat. (#2784)

v20.26.6 (2024-09-27)

Bugfixes - 20.26.6

•: Properly quote string placeholders in activation script templates to mitigate potential command injection - by @y5c4l3. (#2768)

v20.26.5 (2024-09-17)

Bugfixes - 20.26.5

•: Upgrade embedded wheels: setuptools to 75.1.0 from 74.1.2 - by @gaborbernat. (#2765)

v20.26.4 (2024-09-07)

Bugfixes - 20.26.4

no longer create () output in console during activation of a virtualenv by .bat file. (#2728)
Upgrade embedded wheels:

wheel to 0.44.0 from 0.43.0
pip to 24.2 from 24.1
setuptools to 74.1.2 from 70.1.0 (#2760)

v20.26.3 (2024-06-21)

Bugfixes - 20.26.3

•: Upgrade embedded wheels:

setuptools to 70.1.0 from 69.5.1
pip to 24.1 from 24.0 (#2741)

v20.26.2 (2024-05-13)

Bugfixes - 20.26.2

virtualenv.pyz no longer fails when zipapp path contains a symlink - by @HandSonic and @petamas. (#1949)
Fix bad return code from activate.sh if hashing is disabled - by :user:’fenkes-ibm’. (#2717)

v20.26.1 (2024-04-29)

Bugfixes - 20.26.1

•: fix PATH-based Python discovery on Windows - by @ofek. (#2712)

v20.26.0 (2024-04-23)

Bugfixes - 20.26.0

•: allow builtin discovery to discover specific interpreters (e.g. python3.12) given an unspecific spec (e.g. python3) - by @flying-sheep. (#2709)

v20.25.3 (2024-04-17)

Bugfixes - 20.25.3

•: Python 3.13.0a6 renamed pathmod to parser. (#2702)

v20.25.2 (2024-04-16)

Bugfixes - 20.25.2

•: Upgrade embedded wheels:

setuptools of 69.1.0 to 69.5.1
wheel of 0.42.0 to 0.43.0 (#2699)

v20.25.1 (2024-02-21)

Bugfixes - 20.25.1

•: Upgrade embedded wheels:

setuptools to 69.0.3 from 69.0.2
pip to 23.3.2 from 23.3.1 (#2681)

•: Upgrade embedded wheels:

pip 23.3.2 to 24.0,
setuptools 69.0.3 to 69.1.0. (#2691)

Misc - 20.25.1

•: #2688

v20.25.0 (2023-12-01)

Features - 20.25.0

•: The tests now pass on the CI with Python 3.13.0a2 - by @hroncok. (#2673)

Bugfixes - 20.25.0

•: Upgrade embedded wheels:

•: wheel to 0.41.3 from 0.41.2 (#2665)

•: Upgrade embedded wheels:

wheel to 0.42.0 from 0.41.3
setuptools to 69.0.2 from 68.2.2 (#2669)

v20.24.6 (2023-10-23)

Bugfixes - 20.24.6

Use get_hookimpls method instead of the private attribute in tests. (#2649)
Upgrade embedded wheels:

setuptools to 68.2.2 from 68.2.0
pip to 23.3.1 from 23.2.1 (#2656)

v20.24.5 (2023-09-08)

Bugfixes - 20.24.5

Declare PyPy 3.10 support - by @cclauss. (#2638)
Brew on macOS no longer allows copy builds - disallow choosing this by @gaborbernat. (#2640)
Upgrade embedded wheels:

•: setuptools to 68.2.0 from 68.1.2 (#2642)

v20.24.4 (2023-08-30)

Bugfixes - 20.24.4

•: Upgrade embedded wheels:

setuptools to 68.1.2 from 68.1.0 on 3.8+
wheel to 0.41.2 from 0.41.1 on 3.7+ (#2628)

v20.24.3 (2023-08-11)

Bugfixes - 20.24.3

Fixed ResourceWarning on exit caused by periodic update subprocess (#2472)
Upgrade embedded wheels:

•: wheel to 0.41.1 from 0.41.0 (#2622)

Misc - 20.24.3

•: #2610

v20.24.2 (2023-07-24)

Bugfixes - 20.24.2

•: Upgrade embedded wheels:

pip to 23.2.1 from 23.2
wheel to 0.41.0 from 0.40.0 (#2614)

v20.24.1 (2023-07-19)

Bugfixes - 20.24.1

•: Upgrade embedded wheels:

•: pip to 23.2 from 23.1.2 - by @arielkirkwood (#2611)

v20.24.0 (2023-07-14)

Features - 20.24.0

•: Export the prompt prefix as VIRTUAL_ENV_PROMPT when activating a virtual environment - by @jimporter. (#2194)

Bugfixes - 20.24.0

Fix test suite - by @gaborbernat. (#2592)
Upgrade embedded wheels:

•: setuptools to 68.0.0 from 67.8.0 (#2607)

v20.23.1 (2023-06-16)

Bugfixes - 20.23.1

update and simplify nushell activation script, fixes an issue on Windows resulting in consecutive command not found - by @melMass. (#2572)
Upgrade embedded wheels:

•: setuptools to 67.8.0 from 67.7.2 (#2588)

v20.23.0 (2023-04-27)

Features - 20.23.0

•: Do not install wheel and setuptools seed packages for Python 3.12+. To restore the old behavior use:

for wheel use VIRTUALENV_WHEEL=bundle environment variable or --wheel=bundle CLI flag,
for setuptools use VIRTUALENV_SETUPTOOLS=bundle environment variable or --setuptools=bundle CLI flag.

By @chrysle. (#2487)

•: 3.12 support - by @gaborbernat. (#2558)

Bugfixes - 20.23.0

Prevent PermissionError when using venv creator on systems that deliver files without user write permission - by @kulikjak. (#2543)
Upgrade setuptools to 67.7.2 from 67.6.1 and pip to 23.1.2 from 23.1 - by @szleb. (#2560)

v20.22.0 (2023-04-19)

Features - 20.22.0

•: Drop support for creating Python <=3.6 (including 2) interpreters. Removed pip of 20.3.4, 21.3.1; wheel of 0.37.1; setuptools of 59.6.0, 44.1.1, 50.3.2- by @gaborbernat. (#2548)

v20.21.1 (2023-04-19)

Bugfixes - 20.21.1

Add tox.ini to sdist - by @mtelka. (#2511)
Move the use of ‘let’ in nushell to ensure compatibility with future releases of nushell, where ‘let’ no longer assumes that its initializer is a full expressions. (#2527)
The nushell command ‘str collect’ has been superseded by the ‘str join’ command. The activate.nu script has been updated to reflect this change. (#2532)
Upgrade embedded wheels:

wheel to 0.40.0 from 0.38.4
setuptools to 67.6.1 from 67.4.0
pip to 23.1 from 23.0.1 (#2546)

v20.21.0 (2023-03-12)

Features - 20.21.0

•: Make closure syntax explicitly starts with {||. (#2512)

Bugfixes - 20.21.0

Add print command to nushell print_prompt to ensure compatibility with future release of nushell, where intermediate commands no longer print their result to stdout. (#2514)
Do not assume the default encoding. (#2515)
Make ReentrantFileLock thread-safe and, thereby, fix race condition in virtualenv.cli_run - by @radoering. (#2516)

v20.20.0 (2023-02-28)

Features - 20.20.0

•: Change environment variable existence check in Nushell activation script to not use deprecated command. (#2506)

Bugfixes - 20.20.0

Discover CPython implementations distributed on Windows by any organization - by @faph. (#2504)
Upgrade embedded setuptools to 67.4.0 from 67.1.0 and pip to 23.0.1 from 23.0 - by @gaborbernat. (#2510)

v20.19.0 (2023-02-07)

Features - 20.19.0

•: Allow platformdirs version 3 - by @cdce8p. (#2499)

v20.18.0 (2023-02-06)

Features - 20.18.0

•: Drop 3.6 runtime support (can still create 2.7+) - by @gaborbernat. (#2489)

Bugfixes - 20.18.0

Fix broken prompt in Nushell when activating virtual environment - by @kubouc. (#2481)
Bump embedded pip to 23.0 and setuptools to 67.1 - by @gaborbernat. (#2489)

v20.17.1 (2022-12-05)

Bugfixes - 20.17.1

A py or python spec means any Python rather than CPython - by @gaborbernat. (#2460)
Make activate.nu respect VIRTUAL_ENV_DISABLE_PROMPT and not set the prompt if requested - by @m-lima. (#2461)

v20.17.0 (2022-11-27)

Features - 20.17.0

Change Nushell activation script to be a module meant to be activated as an overlay. (#2422)
Update operator used in Nushell activation script to be compatible with future versions. (#2450)

Bugfixes - 20.17.0

Do not use deprecated API from importlib.resources on Python 3.10 or later - by @gaborbernat. (#2448)
Upgrade embedded setuptools to 65.6.3 from 65.5.1 - by @gaborbernat. (#2451)

v20.16.7 (2022-11-12)

Bugfixes - 20.16.7

Use parent directory of python executable for pyvenv.cfg “home” value per PEP 405 - by @vfazio. (#2440)
In POSIX virtual environments, try alternate binary names if sys._base_executable does not exist - by @vfazio. (#2442)
Upgrade embedded wheel to 0.38.4 and pip to 22.3.1 from 22.3 and setuptools to 65.5.1 from 65.5.0 - by @gaborbernat. (#2443)

v20.16.6 (2022-10-25)

Features - 20.16.6

•: Drop unneeded shims for PyPy3 directory structure (#2426)

Bugfixes - 20.16.6

Fix selected scheme on debian derivatives for python 3.10 when python3-distutils is not installed or the venv scheme is not available - by @asottile. (#2350)
Allow the test suite to pass even with the original C shell (rather than tcsh) - by @kulikjak. (#2418)
Fix fallback handling of downloading wheels for bundled packages - by @schaap. (#2429)
Upgrade embedded setuptools to 65.5.0 from 65.3.0 and pip to 22.3 from 22.2.2 - by @gaborbernat. (#2434)

v20.16.5 (2022-09-07)

Bugfixes - 20.16.5

•: Do not turn echo off for subsequent commands in batch activators (activate.bat and deactivate.bat) - by @pawelszramowski. (#2411)

v20.16.4 (2022-08-29)

Bugfixes - 20.16.4

•: Bump embed setuptools to 65.3 - by @gaborbernat. (#2405)

v20.16.3 (2022-08-04)

Bugfixes - 20.16.3

•: Upgrade embedded pip to 22.2.2 from 22.2.1 and setuptools to 63.4.1 from 63.2.0 - by @gaborbernat. (#2395)

v20.16.2 (2022-07-27)

Bugfixes - 20.16.2

•: Bump embedded pip from 22.2 to 22.2.1 - by @gaborbernat. (#2391)

v20.16.1 (2022-07-26)

Features - 20.16.1

•: Update Nushell activation scripts to version 0.67 - by @kubouch. (#2386)

v20.16.0 (2022-07-25)

Features - 20.16.0

Drop support for running under Python 2 (still can generate Python 2 environments) - by @gaborbernat. (#2382)
Upgrade embedded pip to 22.2 from 22.1.2 and setuptools to 63.2.0 from 62.6.0 - by @gaborbernat. (#2383)

v20.15.1 (2022-06-28)

Bugfixes - 20.15.1

Fix the incorrect operation when setuptools plugins output something into stdout. (#2335)
CPython3Windows creator ignores missing DLLs dir. (#2368)

v20.15.0 (2022-06-25)

Features - 20.15.0

•: Support for Windows embeddable Python package: includes python<VERSION>.zip in the creator sources - by @reksarka. (#1774)

Bugfixes - 20.15.0

Upgrade embedded setuptools to 62.3.3 from 62.6.0 and pip to 22.1.2 from 22.0.4 - by @gaborbernat. (#2348)
Use shlex.quote instead of deprecated pipes.quote in Python 3 - by @frenzymadness. (#2351)
Fix Windows PyPy 3.6 - by @reksarka. (#2363)

v20.14.1 (2022-04-11)

Features - 20.14.1

•: Support for creating a virtual environment from a Python 2.7 framework on macOS 12 - by @nickhutchinson. (#2284)

Bugfixes - 20.14.1

•: Upgrade embedded setuptools to 62.1.0 from 61.0.0 - by @gaborbernat. (#2327)

v20.14.0 (2022-03-25)

Features - 20.14.0

•: Support Nushell activation scripts with nu version 0.60 - by @kubouch. (#2321)

Bugfixes - 20.14.0

•: Upgrade embedded setuptools to 61.0.0 from 60.10.0 - by @gaborbernat. (#2322)

v20.13.4 (2022-03-18)

Bugfixes - 20.13.4

Improve performance of python startup inside created virtualenvs - by @asottile. (#2317)
Upgrade embedded setuptools to 60.10.0 from 60.9.3 - by @gaborbernat. (#2320)

v20.13.3 (2022-03-07)

Bugfixes - 20.13.3

Avoid symlinking the contents of /usr into PyPy3.8+ virtualenvs - by @stefanor. (#2310)
Bump embed pip from 22.0.3 to 22.0.4 - by @gaborbernat. (#2311)

v20.13.2 (2022-02-24)

Bugfixes - 20.13.2

•: Upgrade embedded setuptools to 60.9.3 from 60.6.0 - by @gaborbernat. (#2306)

v20.13.1 (2022-02-05)

Bugfixes - 20.13.1

fix “execv() arg 2 must contain only strings” error on M1 MacOS (#2282)
Upgrade embedded setuptools to 60.5.0 from 60.2.0 - by @asottile. (#2289)
Upgrade embedded pip to 22.0.3 and setuptools to 60.6.0 - by @gaborbernat and @asottile. (#2294)

v20.13.0 (2022-01-02)

Features - 20.13.0

•: Add downloaded wheel information in the relevant JSON embed file to prevent additional downloads of the same wheel. - by @mayeut. (#2268)

Bugfixes - 20.13.0

Fix AttributeError: 'bool' object has no attribute 'error' when creating a Python 2.x virtualenv on macOS - by moreati. (#2269)
Fix PermissionError: [Errno 1] Operation not permitted when creating a Python 2.x virtualenv on macOS/arm64 - by moreati. (#2271)

v20.12.1 (2022-01-01)

Bugfixes - 20.12.1

Try using previous updates of pip, setuptools & wheel when inside an update grace period rather than always falling back to embedded wheels - by @mayeut. (#2265)
New patch versions of pip, setuptools & wheel are now returned in the expected timeframe. - by @mayeut. (#2266)
Manual upgrades of pip, setuptools & wheel are not discarded by a periodic update - by @mayeut. (#2267)

v20.12.0 (2021-12-31)

Features - 20.12.0

•: Sign the python2 exe on Darwin arm64 - by @tmspicer. (#2233)

Bugfixes - 20.12.0

Fix --download option - by @mayeut. (#2120)
Upgrade embedded setuptools to 60.2.0 from 60.1.1 - by @gaborbernat. (#2263)

v20.11.2 (2021-12-29)

Bugfixes - 20.11.2

•: Fix installation of pinned versions of pip, setuptools & wheel - by @mayeut. (#2203)

v20.11.1 (2021-12-29)

Bugfixes - 20.11.1

•: Bump embed setuptools to 60.1.1 from 60.1.0 - by @gaborbernat. (#2258)

v20.11.0 (2021-12-28)

Features - 20.11.0

Avoid deprecation warning from py-filelock argument - by @ofek. (#2237)
Upgrade embedded setuptools to 61.1.0 from 58.3.0 - by @gaborbernat. (#2240)
Drop the runtime dependency of backports.entry-points-selectable - by @hroncok. (#2246)
Fish: PATH variables should not be quoted when being set - by @d3dave. (#2248)

v20.10.0 (2021-11-01)

Features - 20.10.0

If a "venv" install scheme exists in sysconfig, virtualenv now uses it to create new virtual environments. This allows Python distributors, such as Fedora, to patch/replace the default install scheme without affecting the paths in new virtual environments. A similar technique was proposed to Python, for the venv module - by hroncok (#2208)
The activated virtualenv prompt is now always wrapped in parentheses. This affects venvs created with the --prompt attribute, and matches virtualenv’s behavior on par with venv. (#2224)

Bugfixes - 20.10.0

•: Fix broken prompt set up by activate.bat - by @SiggyBar. (#2225)

v20.9.0 (2021-10-23)

Features - 20.9.0

Special-case --prompt . to the name of the current directory - by @rkm. (#2220)
Add libffi-8.dll to pypy windows #2218 - by @mattip

Bugfixes - 20.9.0

Fixed path collision that could lead to a PermissionError or writing to system directories when using PyPy3.8 - by @mgorny. (#2182)
Upgrade embedded setuptools to 58.3.0 from 58.1.0 and pip to 21.3.1 from 21.2.4 - by @gaborbernat. (#2205)
Remove stray closing parenthesis in activate.bat - by @SiggyBar. (#2221)

v20.8.1 (2021-09-24)

Bugfixes - 20.8.1

Fixed a bug where while creating a venv on top of an existing one, without cleaning, when seeded wheel version mismatch occurred, multiple .dist-info directories may be present, confounding entrypoint discovery - by @arcivanov (#2185)
Bump embed setuptools from 58.0.4 to 58.1.0 - by @gaborbernat. (#2195)

Misc - 20.8.1

•: #2189

v20.8.0 (2021-09-16)

upgrade embedded setuptools to 58.0.4 from 57.4.0 and pip to 21.2.4 from 21.2.3
Add nushell activation script

v20.7.2 (2021-08-10)

Bugfixes - 20.7.2

•: Upgrade embedded pip to 21.2.3 from 21.2.2 and wheel to 0.37.0 from 0.36.2 - by @gaborbernat. (#2168)

v20.7.1 (2021-08-09)

Bugfixes - 20.7.1

•: Fix unpacking dictionary items in PythonInfo.install_path (#2165)

v20.7.0 (2021-07-31)

Bugfixes - 20.7.0

•: upgrade embedded pip to 21.2.2 from 21.1.3 and setuptools to 57.4.0 from 57.1.0 - by @gaborbernat (#2159)

Deprecations and Removals - 20.7.0

•: Removed xonsh activator due to this breaking fairly often the CI and lack of support from those packages maintainers, upstream is encouraged to continue supporting the project as a plugin - by @gaborbernat. (#2160)

v20.6.0 (2021-07-14)

Features - 20.6.0

•: Support Python interpreters without distutils (fallback to syconfig in these cases) - by @gaborbernat. (#1910)

v20.5.0 (2021-07-13)

Features - 20.5.0

Plugins now use ‘selectable’ entry points - by @jaraco. (#2093)
add libffi-7.dll to the hard-coded list of dlls for PyPy (#2141)
Use the better maintained platformdirs instead of appdirs - by @gaborbernat. (#2142)

Bugfixes - 20.5.0

•: Bump pip the embedded pip 21.1.3 and setuptools to 57.1.0 - by @gaborbernat. (#2135)

Deprecations and Removals - 20.5.0

•: Drop python 3.4 support as it has been over 2 years since EOL - by @gaborbernat. (#2141)

v20.4.7 (2021-05-24)

Bugfixes - 20.4.7

•: Upgrade embedded pip to 21.1.2 and setuptools to 57.0.0 - by @gaborbernat. (#2123)

v20.4.6 (2021-05-05)

Bugfixes - 20.4.6

•: Fix site.getsitepackages() broken on python2 on debian - by @freundTech. (#2105)

v20.4.5 (2021-05-05)

Bugfixes - 20.4.5

Bump pip to 21.1.1 from 21.0.1 - by @gaborbernat. (#2104)
Fix site.getsitepackages() ignoring --system-site-packages on python2 - by @freundTech. (#2106)

v20.4.4 (2021-04-20)

Bugfixes - 20.4.4

Built in discovery class is always preferred over plugin supplied classes. (#2087)
Upgrade embedded setuptools to 56.0.0 by @gaborbernat. (#2094)

v20.4.3 (2021-03-16)

Bugfixes - 20.4.3

Bump embedded setuptools from 52.0.0 to 54.1.2 - by @gaborbernat (#2069)
Fix PyPy3 stdlib on Windows is incorrect - by @gaborbernat. (#2071)

v20.4.2 (2021-02-01)

Bugfixes - 20.4.2

•: Running virtualenv --upgrade-embed-wheels crashes - by @gaborbernat. (#2058)

v20.4.1 (2021-01-31)

Bugfixes - 20.4.1

•: Bump embedded pip and setuptools packages to latest upstream supported (21.0.1 and 52.0.0) - by @gaborbernat. (#2060)

v20.4.0 (2021-01-19)

Features - 20.4.0

•: On the programmatic API allow passing in the environment variable dictionary to use, defaults to os.environ if not specified - by @gaborbernat. (#2054)

Bugfixes - 20.4.0

•: Upgrade embedded setuptools to 51.3.3 from 51.1.2 - by @gaborbernat. (#2055)

v20.3.1 (2021-01-13)

Bugfixes - 20.3.1

Bump embed pip to 20.3.3, setuptools to 51.1.1 and wheel to 0.36.2 - by @gaborbernat. (#2036)
Allow unfunctioning of pydoc to fail freely so that virtualenvs can be activated under Zsh with set -e (since otherwise unset -f and unfunction exit with 1 if the function does not exist in Zsh) - by @d125q. (#2049)
Drop cached python information if the system executable is no longer present (for example when the executable is a shim and the mapped executable is replaced - such is the case with pyenv) - by @gaborbernat. (#2050)

v20.3.0 (2021-01-10)

Features - 20.3.0

•: The builtin discovery takes now a --try-first-with argument and is first attempted as valid interpreters. One can use this to force discovery of a given python executable when the discovery order/mechanism raises errors - by @gaborbernat. (#2046)

Bugfixes - 20.3.0

On Windows python 3.7+ distributions where the exe shim is missing fallback to the old ways - by @gaborbernat. (#1986)
When discovering interpreters on Windows, via the PEP-514, prefer PythonCore releases over other ones. virtualenv is used via pip mostly by this distribution, so prefer it over other such as conda - by @gaborbernat. (#2046)

v20.2.2 (2020-12-07)

Bugfixes - 20.2.2

•: Bump pip to 20.3.1, setuptools to 51.0.0 and wheel to 0.36.1 - by @gaborbernat. (#2029)

v20.2.1 (2020-11-23)

No significant changes.

v20.2.0 (2020-11-21)

Features - 20.2.0

Optionally skip VCS ignore directive for entire virtualenv directory, using option no-vcs-ignore, by default False. (#2003)
Add --read-only-app-data option to allow for creation based on an existing app data cache which is non-writable. This may be useful (for example) to produce a docker image where the app-data is pre-populated.

ENV \


    VIRTUALENV_OVERRIDE_APP_DATA=/opt/virtualenv/cache \


    VIRTUALENV_SYMLINK_APP_DATA=1
RUN virtualenv venv && rm -rf venv
ENV VIRTUALENV_READ_ONLY_APP_DATA=1
USER nobody
# this virtualenv has symlinks into the read-only app-data cache
RUN virtualenv /tmp/venv

Patch by @asottile. (#2009)

Bugfixes - 20.2.0

•: Fix processing of the VIRTUALENV_PYTHON environment variable and make it multi-value as well (separated by comma) - by @pneff. (#1998)

v20.1.0 (2020-10-25)

Features - 20.1.0

•: The python specification can now take one or more values, first found is used to create the virtual environment - by @gaborbernat. (#1995)

v20.0.35 (2020-10-15)

Bugfixes - 20.0.35

Bump embedded setuptools from 50.3.0 to 50.3.1 - by @gaborbernat. (#1982)
After importing virtualenv passing cwd to a subprocess calls breaks with invalid directory - by @gaborbernat. (#1983)

v20.0.34 (2020-10-12)

Bugfixes - 20.0.34

Align with venv module when creating virtual environments with builtin creator on Windows 3.7 and later - by @gaborbernat. (#1782)
Handle Cygwin path conversion in the activation script - by @davidcoghlan. (#1969)

v20.0.33 (2020-10-04)

Bugfixes - 20.0.33

Fix None type error in cygwin if POSIX path in dest - by @danyeaw. (#1962)
Fix Python 3.4 incompatibilities (added back to the CI) - by @gaborbernat. (#1963)

v20.0.32 (2020-10-01)

Bugfixes - 20.0.32

For activation scripts always use UNIX line endings (unless it’s BATCH shell related) - by @saytosid. (#1818)
Upgrade embedded pip to 20.2.1 and setuptools to 49.4.0 - by @gaborbernat. (#1918)
Avoid spawning new windows when doing seed package upgrades in the background on Windows - by @gaborbernat. (#1928)
Fix a bug that reading and writing on the same file may cause race on multiple processes. (#1938)
Upgrade embedded setuptools to 50.2.0 and pip to 20.2.3 - by @gaborbernat. (#1939)
Provide correct path for bash activator in cygwin or msys2 - by @danyeaw. (#1940)
Relax importlib requirement to allow version<3 - by @usamasadiq (#1953)
pth files were not processed on CPython2 if $PYTHONPATH was pointing to site-packages/ - by @navytux. (#1959) (#1960)

v20.0.31 (2020-08-17)

Bugfixes - 20.0.31

•: Upgrade embedded pip to 20.2.1, setuptools to 49.6.0 and wheel to 0.35.1 - by @gaborbernat. (#1918)

v20.0.30 (2020-08-04)

Bugfixes - 20.0.30

•: Upgrade pip to 20.2.1 and setuptools to 49.2.1 - by @gaborbernat. (#1915)

v20.0.29 (2020-07-31)

Bugfixes - 20.0.29

•: Upgrade embedded pip from version 20.1.2 to 20.2 - by @gaborbernat. (#1909)

v20.0.28 (2020-07-24)

Bugfixes - 20.0.28

Fix test suite failing if run from system Python - by @gaborbernat. (#1882)
Provide setup_logging flag to python API so that users can bypass logging handling if their application already performs this - by @gaborbernat. (#1896)
Use \n instead if \r\n as line separator for report (because Python already performs this transformation automatically upon write to the logging pipe) - by @gaborbernat. (#1905)

v20.0.27 (2020-07-15)

Bugfixes - 20.0.27

No longer preimport threading to fix support for gpython and gevent - by @navytux. (#1897)
Upgrade setuptools from 49.2.0 on Python 3.5+ - by @gaborbernat. (#1898)

v20.0.26 (2020-07-07)

Bugfixes - 20.0.26

Bump dependency distutils >= 0.3.1 - by @gaborbernat. (#1880)
Improve periodic update handling:

better logging output while running and enable logging on background process call ( _VIRTUALENV_PERIODIC_UPDATE_INLINE may be used to debug behavior inline)
fallback to unverified context when querying the PyPi for release date,
stop downloading wheels once we reach the embedded version,

by @gaborbernat. (#1883)

Do not print error message if the application exists with SystemExit(0) - by @gaborbernat. (#1885)
Upgrade embedded setuptools from 47.3.1 to 49.1.0 for Python 3.5+ - by @gaborbernat. (#1887)

v20.0.25 (2020-06-23)

Bugfixes - 20.0.25

•: Fix that when the app-data seeders image creation fails the exception is silently ignored. Avoid two virtual environment creations to step on each others toes by using a lock while creating the base images. By @gaborbernat. (#1869)

v20.0.24 (2020-06-22)

Features - 20.0.24

•: Ensure that the seeded packages do not get too much out of date:

add a CLI flag that triggers upgrade of embedded wheels under upgrade-embed-wheels
periodically (once every 14 days) upgrade the embedded wheels in a background process, and use them if they have been released for more than 28 days (can be disabled via no-periodic-update)

More details under Wheel acquisition - by @gaborbernat. (#1821)

•: Upgrade embed wheel content:

ship wheels for Python 3.9 and 3.10
upgrade setuptools for Python 3.5+ from 47.1.1 to 47.3.1

by @gaborbernat. (#1841)

•: Display the installed seed package versions in the final summary output, for example:

created virtual environment CPython3.8.3.final.0-64 in 350ms


  creator CPython3Posix(dest=/x, clear=True, global=False)


  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/y/virtualenv)


    added seed packages: pip==20.1.1, setuptools==47.3.1, wheel==0.34.2

by @gaborbernat. (#1864)

Bugfixes - 20.0.24

Do not generate/overwrite .gitignore if it already exists at destination path - by @gaborbernat. (#1862)
Improve error message for no .dist-info inside the app-data copy seeder - by @gaborbernat. (#1867)

Improved Documentation - 20.0.24

How seeding mechanisms discover (and automatically keep it up to date) wheels at Wheel acquisition - by @gaborbernat. (#1821)
How distributions should handle shipping their own embedded wheels at Distribution maintainer patching - by @gaborbernat. (#1840)

v20.0.23 (2020-06-12)

Bugfixes - 20.0.23

•: Fix typo in setup.cfg - by @RowdyHowell. (#1857)

v20.0.22 (2020-06-12)

Bugfixes - 20.0.22

Relax importlib.resources requirement to also allow version 2 - by @asottile. (#1846)
Upgrade embedded setuptools to 44.1.1 for python 2 and 47.1.1 for python3.5+ - by @gaborbernat. (#1855)

v20.0.21 (2020-05-20)

Features - 20.0.21

•: Generate ignore file for version control systems to avoid tracking virtual environments by default. Users should remove these files if still want to track. For now we support only git by @gaborbernat. (#1806)

Bugfixes - 20.0.21

Fix virtualenv fails sometimes when run concurrently, --clear-app-data conflicts with clear flag when abbreviation is turned on. To bypass this while allowing abbreviated flags on the command line we had to move it to reset-app-data - by @gaborbernat. (#1824)
Upgrade embedded setuptools to 46.4.0 from 46.1.3 on Python 3.5+, and pip from 20.1 to 20.1.1 - by @gaborbernat. (#1827)
Seeder pip now correctly handles --extra-search-dir - by @frenzymadness. (#1834)

v20.0.20 (2020-05-04)

Bugfixes - 20.0.20

Fix download fails with python 3.4 - by @gaborbernat. (#1809)
Fixes older CPython2 versions use _get_makefile_filename instead of get_makefile_filename on sysconfig - by @ianw. (#1810)
Fix download is True by default - by @gaborbernat. (#1813)
Fail app-data seed operation when wheel download fails and better error message - by @gaborbernat. (#1814)

v20.0.19 (2020-05-03)

Bugfixes - 20.0.19

Fix generating a Python 2 environment from Python 3 creates invalid python activator - by @gaborbernat. (#1776)
Fix pinning seed packages via app-data seeder raised Invalid Requirement - by @gaborbernat. (#1779)
Do not stop interpreter discovery if we fail to find the system interpreter for a executable during discovery - by @gaborbernat. (#1781)
On CPython2 POSIX platforms ensure syconfig.get_makefile_filename exists within the virtual environment (this is used by some c-extension based libraries - e.g. numpy - for building) - by @gaborbernat. (#1783)
Better handling of options copies and symlinks. Introduce priority of where the option is set to follow the order: CLI, env var, file, hardcoded. If both set at same level prefers copy over symlink. - by @gaborbernat. (#1784)
Upgrade pip for Python 2.7 and 3.5+ from 20.0.2 to 20.1 - by @gaborbernat. (#1793)
Fix CPython is not discovered from Windows registry, and discover pythons from Windows registry in decreasing order by version - by @gaborbernat. (#1796)
Fix symlink detection for creators - by @asottile (#1803)

v20.0.18 (2020-04-16)

Bugfixes - 20.0.18

•: Importing setuptools before cli_run could cause our python information query to fail due to setuptools patching distutils.dist.Distribution - by @gaborbernat. (#1771)

v20.0.17 (2020-04-09)

Features - 20.0.17

•: Extend environment variables checked for configuration to also check aliases (e.g. setting either VIRTUALENV_COPIES or VIRTUALENV_ALWAYS_COPY will work) - by @gaborbernat. (#1763)

v20.0.16 (2020-04-04)

Bugfixes - 20.0.16

•: Allow seed wheel files inside the extra-search-dir folders that do not have Requires-Python metadata specified, these are considered compatible with all python versions - by @gaborbernat. (#1757)

v20.0.15 (2020-03-27)

Features - 20.0.15

•: Upgrade embedded setuptools to 46.1.3 from 46.1.1 - by @gaborbernat. (#1752)

v20.0.14 (2020-03-25)

Features - 20.0.14

Remove __PYVENV_LAUNCHER__ on macOs for Python 3.7.(<8) and 3.8.(<3) on interpreter startup via pth file, this pulls in the upstream patch - by @gaborbernat. (#1704)
Upgrade embedded setuptools for Python 3.5+ to 46.1.1, for Python 2.7 to 44.1.0 - by @gaborbernat. (#1745)

Bugfixes - 20.0.14

•: Fix discovery of interpreter by name from PATH that does not match a spec format - by @gaborbernat. (#1746)

v20.0.13 (2020-03-19)

Bugfixes - 20.0.13

Do not fail when the pyc files is missing for the host Python 2 - by @gaborbernat. (#1738)
Support broken Packaging pythons that put the include headers under distutils pattern rather than sysconfig one - by @gaborbernat. (#1739)

v20.0.12 (2020-03-19)

Bugfixes - 20.0.12

•: Fix relative path discovery of interpreters - by @gaborbernat. (#1734)

v20.0.11 (2020-03-18)

Features - 20.0.11

•: Improve error message when the host python does not satisfy invariants needed to create virtual environments (now we print which host files are incompatible/missing and for which creators when no supported creator can be matched, however we found creators that can describe the given Python interpreter - will still print no supported creator for Jython, however print exactly what host files do not allow creation of virtual environments in case of CPython/PyPy) - by @gaborbernat. (#1716)

Bugfixes - 20.0.11

Support Python 3 Framework distributed via XCode in macOs Catalina and before - by @gaborbernat. (#1663)
Fix Windows Store Python support, do not allow creation via symlink as that’s not going to work by design - by @gaborbernat. (#1709)
Fix activate_this.py throws AttributeError on Windows when virtual environment was created via cross python mechanism - by @gaborbernat. (#1710)
Fix --no-pip, --no-setuptools, --no-wheel not being respected - by @gaborbernat. (#1712)
Allow missing .py files if a compiled .pyc version is available - by @tucked. (#1714)
Do not fail if the distutils/setuptools patch happens on a C-extension loader (such as zipimporter on Python 3.7 or earlier) - by @gaborbernat. (#1715)
Support Python 2 implementations that require the landmark files and site.py to be in platform standard library instead of the standard library path of the virtual environment (notably some RHEL ones, such as the Docker image amazonlinux:1) - by @gaborbernat. (#1719)
Allow the test suite to pass even when called with the system Python - to help repackaging of the tool for Linux distributions - by @gaborbernat. (#1721)
Also generate pipx.y console script beside pip-x.y to be compatible with how pip installs itself - by @gaborbernat. (#1723)
Automatically create the application data folder if it does not exists - by @gaborbernat. (#1728)

Improved Documentation - 20.0.11

•: supports details now explicitly what Python installations we support - by @gaborbernat. (#1714)

v20.0.10 (2020-03-10)

Bugfixes - 20.0.10

Fix acquiring python information might be altered by distutils configuration files generating incorrect layout virtual environments - by @gaborbernat. (#1663)
Upgrade embedded setuptools to 46.0.0 from 45.3.0 on Python 3.5+ - by @gaborbernat. (#1702)

Improved Documentation - 20.0.10

Document requirements (pip + index server) when installing via pip under the installation section - by @gaborbernat. (#1618)
Document installing from non PEP-518 systems - @gaborbernat. (#1619)
Document installing latest unreleased version from Github - @gaborbernat. (#1620)

v20.0.9 (2020-03-08)

Bugfixes - 20.0.9

pythonw.exe works as python.exe on Windows - by @gaborbernat. (#1686)
Handle legacy loaders for virtualenv import hooks used to patch distutils configuration load - by @gaborbernat. (#1690)
Support for python 2 platforms that store landmark files in platstdlib over stdlib (e.g. RHEL) - by @gaborbernat. (#1694)
Upgrade embedded setuptools to 45.3.0 from 45.2.0 for Python 3.5+ - by @gaborbernat. (#1699)

v20.0.8 (2020-03-04)

Bugfixes - 20.0.8

Having distutils configuration files that set prefix and install_scripts cause installation of packages in the wrong location - by @gaborbernat. (#1663)
Fix PYTHONPATH being overridden on Python 2 — by @jd. (#1673)
Fix list configuration value parsing from config file or environment variable - by @gaborbernat. (#1674)
Fix Batch activation script shell prompt to display environment name by default - by @spetafree. (#1679)
Fix startup on Python 2 is slower for virtualenv - this was due to setuptools calculating it’s working set distribution - by @gaborbernat. (#1682)
Fix entry points are not populated for editable installs on Python 2 due to setuptools working set being calculated before easy_install.pth runs - by @gaborbernat. (#1684)
Fix attr: import fails for setuptools - by @gaborbernat. (#1685)

v20.0.7 (2020-02-26)

Bugfixes - 20.0.7

•: Disable distutils fixup for python 3 until pypa/pip #7778 is fixed and released - by @gaborbernat. (#1669)

v20.0.6 (2020-02-26)

Bugfixes - 20.0.6

Fix global site package always being added with bundled macOs python framework builds - by @gaborbernat. (#1561)
Fix generated scripts use host version info rather than target - by @gaborbernat. (#1600)
Fix circular prefix reference with single elements (accept these as if they were system executables, print a info about them referencing themselves) - by @gaborbernat. (#1632)
Handle the case when the application data folder is read-only:

the application data folder is now controllable via app-data,
clear-app-data now cleans the entire application data folder, not just the app-data seeder path,
check if the application data path passed in does not exist or is read-only, and fallback to a temporary directory,
temporary directory application data is automatically cleaned up at the end of execution,
symlink-app-data is always False when the application data is temporary

by @gaborbernat. (#1640)

Fix PyPy 2 builtin modules are imported from standard library, rather than from builtin - by @gaborbernat. (#1652)
Fix creation of entry points when path contains spaces - by @nsoranzo. (#1660)
Fix relative paths for the zipapp (for python 3.7+) - by @gaborbernat. (#1666)

v20.0.5 (2020-02-21)

Features - 20.0.5

Also create pythonX.X executables when creating pypy virtualenvs - by @asottile (#1612)
Fail with better error message if trying to install source with unsupported setuptools, allow setuptools-scm >= 2 and move to legacy setuptools-scm format to support better older platforms (CentOS 7 and such) - by @gaborbernat. (#1621)
Report of the created virtual environment is now split across four short lines rather than one long - by @gaborbernat (#1641)

Bugfixes - 20.0.5

Add macOs Python 2 Framework support (now we test it with the CI via brew) - by @gaborbernat (#1561)
Fix losing of libpypy-c.so when the pypy executable is a symlink - by @asottile (#1614)
Discover python interpreter in a case insensitive manner - by @PrajwalM2212 (#1624)
Fix cross interpreter support when the host python sets sys.base_executable based on __PYVENV_LAUNCHER__ - by @cjolowicz (#1643)

v20.0.4 (2020-02-14)

Features - 20.0.4

•: When aliasing interpreters, use relative symlinks - by @asottile. (#1596)

Bugfixes - 20.0.4

Allow the use of / as pathname component separator on Windows - by vphilippon (#1582)
Lower minimal version of six required to 1.9 - by ssbarnea (#1606)

v20.0.3 (2020-02-12)

Bugfixes - 20.0.3

On Python 2 with Apple Framework builds the global site package is no longer added when the system-site-packages is not specified - by @gaborbernat. (#1561)
Fix system python discovery mechanism when prefixes contain relative parts (e.g. ..) by resolving paths within the python information query - by @gaborbernat. (#1583)
Expose a programmatic API as from virtualenv import cli_run - by @gaborbernat. (#1585)
Fix app-data seeder injects a extra .dist-info.virtualenv path that breaks importlib.metadata, now we inject an extra .virtualenv - by @gaborbernat. (#1589)

Improved Documentation - 20.0.3

•: Document a programmatic API as from virtualenv import cli_run under Python - by @gaborbernat. (#1585)

v20.0.2 (2020-02-11)

Features - 20.0.2

Print out a one line message about the created virtual environment when no verbose is set, this can now be silenced to get back the original behavior via the quiet flag - by @pradyunsg. (#1557)
Allow virtualenv’s app data cache to be overridden by VIRTUALENV_OVERRIDE_APP_DATA - by @asottile. (#1559)
Passing in the virtual environment name/path is now required (no longer defaults to venv) - by @gaborbernat. (#1568)
Add a CLI flag with-traceback that allows displaying the stacktrace of the virtualenv when a failure occurs - by @gaborbernat. (#1572)

Bugfixes - 20.0.2

Support long path names for generated virtual environment console entry points (such as pip) when using the app-data seeder - by @gaborbernat. (#997)
Improve python discovery mechanism:

do not fail if there are executables that fail to query (e.g. for not having execute access to it) on the PATH,
beside the prefix folder also try with the platform dependent binary folder within that,

by @gaborbernat. (#1545)

When copying (either files or trees) do not copy the permission bits, last access time, last modification time, and flags as access to these might be forbidden (for example in case of the macOs Framework Python) and these are not needed for the user to use the virtual environment - by @gaborbernat. (#1561)
While discovering a python executables interpreters that cannot be queried are now displayed with info level rather than warning, so now they’re no longer shown by default (these can be just executables to which we don’t have access or that are broken, don’t warn if it’s not the target Python we want) - by @gaborbernat. (#1574)
The app-data seeder no longer symlinks the packages on UNIX and copies on Windows. Instead by default always copies, however now has the symlink-app-data flag allowing users to request this less robust but faster method - by @gaborbernat. (#1575)

Improved Documentation - 20.0.2

Add link to the legacy documentation for the changelog by @jezdez. (#1547)
Fine tune the documentation layout: default width of theme, allow tables to wrap around, soft corners for code snippets - by @pradyunsg. (#1548)

v20.0.1 (2020-02-10)

Features - 20.0.1

•: upgrade embedded setuptools to 45.2.0 from 45.1.0 for Python 3.4+ - by @gaborbernat. (#1554)

Bugfixes - 20.0.1

Virtual environments created via relative path on Windows creates bad console executables - by @gaborbernat. (#1552)
Seems sometimes venvs created set their base executable to themselves; we accept these without question, so we handle virtual environments as system pythons causing issues - by @gaborbernat. (#1553)

v20.0.0. (2020-02-10)

Improved Documentation - 20.0.0.

•: Fixes typos, repeated words and inconsistent heading spacing. Rephrase parts of the development documentation and CLI documentation. Expands shorthands like env var and config to their full forms. Uses descriptions from respective documentation, for projects listed in related links - by @pradyunsg. (#1540)

v20.0.0b2 (2020-02-04)

Features - 20.0.0b2

•: Improve base executable discovery mechanism:

print at debug level why we refuse some candidates,
when no candidates match exactly, instead of hard failing fallback to the closest match where the priority of matching attributes is: python implementation, major version, minor version, architecture, patch version, release level and serial (this is to facilitate things to still work when the OS upgrade replace/upgrades the system python with a never version, than what the virtualenv host python was created with),
always resolve system_executable information during the interpreter discovery, and the discovered environment is the system interpreter instead of the venv/virtualenv (this happened before lazily the first time we accessed, and caused reporting that the created virtual environment is of type of the virtualenv host python version, instead of the system pythons version - these two can differ if the OS upgraded the system python underneath and the virtualenv host was created via copy),

by @gaborbernat. (#1515)

Generate bash and fish activators on Windows too (as these can be available with git bash, cygwin or mysys2) - by @gaborbernat. (#1527)
Upgrade the bundled wheel package from 0.34.0 to 0.34.2 - by @gaborbernat. (#1531)

Bugfixes - 20.0.0b2

Bash activation script should have no extensions instead of .sh (this fixes the virtualenvwrapper integration) - by @gaborbernat. (#1508)
Show less information when we run with a single verbosity (-v):

no longer shows accepted interpreters information (as the last proposed one is always the accepted one),
do not display the str_spec attribute for PythonSpec as these can be deduced from the other attributes,
for the app-data seeder do not show the type of lock, only the path to the app data directory,

By @gaborbernat. (#1510)

Fixed cannot discover a python interpreter that has already been discovered under a different path (such is the case when we have multiple symlinks to the same interpreter) - by @gaborbernat. (#1512)
Support relative paths for -p - by @gaborbernat. (#1514)
Creating virtual environments in parallel fail with cannot acquire lock within app data - by @gaborbernat. (#1516)
pth files were not processed under Debian CPython2 interpreters - by @gaborbernat. (#1517)
Fix prompt not displayed correctly with upcoming fish 3.10 due to us not preserving $pipestatus - by @krobelus. (#1530)
Stable order within pyenv.cfg and add include-system-site-packages only for creators that reference a global Python - by user:gaborbernat. (#1535)

Improved Documentation - 20.0.0b2

Create the first iteration of the new documentation - by @gaborbernat. (#1465)
Project readme is now of type MarkDown instead of reStructuredText - by @gaborbernat. (#1531)

v20.0.0b1 (2020-01-28)

First public release of the rewrite. Everything is brand new and just added.
--download defaults to False
No longer replaces builtin site module with custom version baked within virtualenv code itself. A simple shim module is used to fix up things on Python 2 only.

WARNING:

The current virtualenv is the second iteration of implementation. From version 0.8 all the way to 16.7.9 we numbered the first iteration. Version 20.0.0b1 is a complete rewrite of the package, and as such this release history starts from there. The old changelog is still available in the legacy branch documentation.

AUTHOR

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