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書名： Mastering Python
作者名： Rick van Hattem
本章字數： 296字
更新時間： 2021-07-16 11:10:31

Bootstrapping pip using ensurepip

Slowly, the pip package manager has been replacing easy_install since its introduction in 2008. Since Python 3.4, it has even become the default and is bundled with Python. Since Python 3.4 onward, it is installed by default within both the regular Python environment and that of pyvenv; before that, a manual install is required. To automatically install pip in Python 3.4 and above, the ensurepip library is used. This is a library that handles automatic installation and/or upgrades of pip, so it is at least as recent as the one bundled with ensurepip.

ensurepip usage

The usage of ensurepip is fairly straightforward. Just run python -m ensurepip to guarantee a pip version or python -m ensurepip --upgrade to make sure that pip will be at least the version that is bundled with ensurepip.

In addition to installing the regular pip shortcut, this will also install the pipX and pipX.Y links, which allow you to select a specific Python version. When using Python 2 and Python 3 simultaneously, this allows you to install packages within Python 2 and Python 3 with pip2 and pip3, respectively. This means that if you use python -m ensurepip on Python 3.5 you will get pip, pip3, and pip3.5 commands installed in your environment.

Manual pip install

The ensurepip package is great if you are using Python 3.4 or above. Below that, however, you need to install pip manually. Actually, this is surprisingly easy. It involves just two steps:

Download the get-pip.py file: https://bootstrap.pypa.io/get-pip.py.
Execute the get-pip.py file: python get-pip.py.

Tip

If the ensurepip command fails due to permission errors, it can be useful to supply the --user argument. This allows you to install pip inside the user specific site packages directory, so root/admin access is not required.

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Mastering Python

Bootstrapping pip using ensurepip

ensurepip usage

Manual pip install

Tip