安装pip工具

Posted 2020-08-28 evil_liu

Python 2.7.9+ and 3.4+

Good news! Python 3.4 (released March 2014) and Python 2.7.9 (released December 2014) ship with Pip. This is the best feature of any Python release. It makes the community‘s wealth of libraries accessible to everyone. Newbies are no longer excluded from using community libraries by the prohibitive difficulty of setup. In shipping with a package manager, Python joins Ruby, Node.js,Haskell, Perl, Go--almost every other contemporary language with a majority open-source community. Thank you Python.

Of course, that doesn‘t mean Python packaging is problem solved. The experience remains frustrating. I discuss this in Stack Overflow question Does Python have a package/module management system?.

And, alas for everyone using Python 2.7.8 or earlier (a sizable portion of the community). There‘s no plan to ship Pip to you. Manual instructions follow.

Python 2 ≤ 2.7.8 and Python 3 ≤ 3.3

Flying in the face of its ‘batteries included‘ motto, Python ships without a package manager. To make matters worse, Pip was--until recently--ironically difficult to install.

Official instructions

Per https://pip.pypa.io/en/stable/installing/#do-i-need-to-install-pip:

Download get-pip.py, being careful to save it as a .py file rather than .txt. Then, run it from the command prompt:

python get-pip.py

You possibly need an administrator command prompt to do this. Follow Start a Command Prompt as an Administrator (Microsoft TechNet).

Alternative instructions

The official documentation tells users to install Pip and each of its dependencies from source. That‘s tedious for the experienced, and prohibitively difficult for newbies.

For our sake, Christoph Gohlke prepares Windows installers (.msi) for popular Python packages. He builds installers for all Python versions, both 32 and 64 bit. You need to

1. Install setuptools
2. Install pip

For me, this installed Pip at C:\Python27\Scripts\pip.exe. Find pip.exe on your computer, then add its folder (for example, C:\Python27\Scripts) to your path (Start / Edit environment variables). Now you should be able to run pip from the command line. Try installing a package:

pip install httpie

There you go (hopefully)! Solutions for common problems are given below:

Proxy problems

If you work in an office, you might be behind a HTTP proxy. If so, set the environment variables http_proxy and https_proxy. Most Python applications (and other free software) respect these. Example syntax:

http://proxy_url:port
http://username:[email protected]_url:port

If you‘re really unlucky, your proxy might be a Microsoft NTLM proxy. Free software can‘t cope. The only solution is to install a free software friendly proxy that forwards to the nasty proxy.http://cntlm.sourceforge.net/

Unable to find vcvarsall.bat

Python modules can be part written in C or C++. Pip tries to compile from source. If you don‘t have a C/C++ compiler installed and configured, you‘ll see this cryptic error message.

Error: Unable to find vcvarsall.bat

You can fix that by installing a C++ compiler such as MinGW or Visual C++. Microsoft actually ship one specifically for use with Python. Or try Microsoft Visual C++ Compiler for Python 2.7.

Often though it‘s easier to check Christoph‘s site for your package.