Installing packages using pip and virtual environments¶
This guide discusses how to install packages using pip and a virtual environment manager: either venv for Python 3 or virtualenv for Python 2. These are the lowest-level tools for managing Python packages and are recommended if higher-level tools do not suit your needs.
pip is the reference Python package manager. It’s used to install and update packages. You’ll need to make sure you have the latest version of pip installed.
Debian and most other distributions include a python-pip package; if you want to use the Linux distribution-provided versions of pip, see Installing pip/setuptools/wheel with Linux Package Managers.
You can also install pip yourself to ensure you have the latest version. It’s recommended to use the system pip to bootstrap a user installation of pip:
python3 -m pip install --user --upgrade pip python3 -m pip --version
Afterwards, you should have the latest version of pip installed in your user site:
pip 21.1.3 from $HOME/.local/lib/python3.9/site-packages (python 3.9)
The Python installers for Windows include pip. You can make sure that pip is up-to-date by running:
py -m pip install --upgrade pip py -m pip --version
Afterwards, you should have the latest version of pip:
pip 21.1.3 from c:\python39\lib\site-packages (Python 3.9.4)
If you are using Python 3.3 or newer, the
venv module is
the preferred way to create and manage virtual environments.
venv is included in the Python standard library and requires no additional installation.
If you are using venv, you may skip this section.
virtualenv is used to manage Python packages for different projects. Using virtualenv allows you to avoid installing Python packages globally which could break system tools or other projects. You can install virtualenv using pip.
python3 -m pip install --user virtualenv
py -m pip install --user virtualenv
Creating a virtual environment¶
venv (for Python 3) and virtualenv (for Python 2) allow you to manage separate package installations for different projects. They essentially allow you to create a “virtual” isolated Python installation and install packages into that virtual installation. When you switch projects, you can simply create a new virtual environment and not have to worry about breaking the packages installed in the other environments. It is always recommended to use a virtual environment while developing Python applications.
To create a virtual environment, go to your project’s directory and run
venv. If you are using Python 2, replace
in the below commands.
python3 -m venv env
py -m venv env
The second argument is the location to create the virtual environment. Generally, you
can just create this in your project and call it
venv will create a virtual Python installation in the
You should exclude your virtual environment directory from your version
control system using
.gitignore or similar.
Activating a virtual environment¶
Before you can start installing or using packages in your virtual environment you’ll
need to activate it. Activating a virtual environment will put the
pip executables into your shell’s
You can confirm you’re in the virtual environment by checking the location of your Python interpreter:
It should be in the
As long as your virtual environment is activated pip will install packages into that specific environment and you’ll be able to import and use packages in your Python application.
Leaving the virtual environment¶
If you want to switch projects or otherwise leave your virtual environment, simply run:
If you want to re-enter the virtual environment just follow the same instructions above about activating a virtual environment. There’s no need to re-create the virtual environment.
python3 -m pip install requests
py -m pip install requests
pip should download requests and all of its dependencies and install them:
Collecting requests Using cached requests-2.18.4-py2.py3-none-any.whl Collecting chardet<3.1.0,>=3.0.2 (from requests) Using cached chardet-3.0.4-py2.py3-none-any.whl Collecting urllib3<1.23,>=1.21.1 (from requests) Using cached urllib3-1.22-py2.py3-none-any.whl Collecting certifi>=2017.4.17 (from requests) Using cached certifi-2017.7.27.1-py2.py3-none-any.whl Collecting idna<2.7,>=2.5 (from requests) Using cached idna-2.6-py2.py3-none-any.whl Installing collected packages: chardet, urllib3, certifi, idna, requests Successfully installed certifi-2017.7.27.1 chardet-3.0.4 idna-2.6 requests-2.18.4 urllib3-1.22
Installing specific versions¶
pip allows you to specify which version of a package to install using
version specifiers. For example, to install
a specific version of
python3 -m pip install requests==2.18.4
py -m pip install requests==2.18.4
To install the latest
2.x release of requests:
python3 -m pip install requests>=2.0.0,<3.0.0
py -m pip install requests>=2.0.0,<3.0.0
To install pre-release versions of packages, use the
python3 -m pip install --pre requests
py -m pip install --pre requests
Some packages have optional extras. You can tell pip to install these by specifying the extra in brackets:
python3 -m pip install requests[security]
py -m pip install requests[security]
Installing from source¶
pip can install a package directly from source, for example:
cd google-auth python3 -m pip install .
cd google-auth py -m pip install .
Additionally, pip can install packages from source in development mode, meaning that changes to the source directory will immediately affect the installed package without needing to re-install:
python3 -m pip install --editable .
py -m pip install --editable .
Installing from version control systems¶
pip can install packages directly from their version control system. For example, you can install directly from a git repository:
For more information on supported version control systems and syntax, see pip’s documentation on VCS Support.
Installing from local archives¶
If you have a local copy of a Distribution Package’s archive (a zip, wheel, or tar file) you can install it directly with pip:
python3 -m pip install requests-2.18.4.tar.gz
py -m pip install requests-2.18.4.tar.gz
If you have a directory containing archives of multiple packages, you can tell pip to look for packages there and not to use the Python Package Index (PyPI) at all:
python3 -m pip install --no-index --find-links=/local/dir/ requests
py -m pip install --no-index --find-links=/local/dir/ requests
This is useful if you are installing packages on a system with limited connectivity or if you want to strictly control the origin of distribution packages.
Using other package indexes¶
If you want to download packages from a different index than the
Python Package Index (PyPI), you can use the
python3 -m pip install --index-url http://index.example.com/simple/ SomeProject
py -m pip install --index-url http://index.example.com/simple/ SomeProject
If you want to allow packages from both the Python Package Index (PyPI)
and a separate index, you can use the
--extra-index-url flag instead:
python3 -m pip install --extra-index-url http://index.example.com/simple/ SomeProject
py -m pip install --extra-index-url http://index.example.com/simple/ SomeProject
pip can upgrade packages in-place using the
--upgrade flag. For example, to
install the latest version of
requests and all of its dependencies:
python3 -m pip install --upgrade requests
py -m pip install --upgrade requests
Using requirements files¶
Instead of installing packages individually, pip allows you to declare all
dependencies in a Requirements File. For
example you could create a
requirements.txt file containing:
And tell pip to install all of the packages in this file using the
python3 -m pip install -r requirements.txt
py -m pip install -r requirements.txt
Pip can export a list of all installed packages and their versions using the
python3 -m pip freeze
py -m pip freeze
Which will output a list of package specifiers such as:
cachetools==2.0.1 certifi==2017.7.27.1 chardet==3.0.4 google-auth==1.1.1 idna==2.6 pyasn1==0.3.6 pyasn1-modules==0.1.4 requests==2.18.4 rsa==3.4.2 six==1.11.0 urllib3==1.22
This is useful for creating Requirements Files that can re-create the exact versions of all packages installed in an environment.