在CentOS 6安装包python-setuptools修复了它。

yum install python-setuptools

当我以不同于创建它的用户的身份激活virtualenv时，我遇到了这个问题。似乎是权限问题。当我尝试@cwc的答案并在输出中看到这一点时，我发现了这一点:

Installing easy_install script to /path/env/bin
error: /path/env/bin/easy_install: Permission denied

切换回创建virtualenv的用户，然后运行原来的pip install命令，没有任何问题。希望这能有所帮助!

I have had the same problem when I used easy-install to install pip for python 2.7.14. For me the solution was (might not be the best, but worked for me, and this is probably the simplest) that the folder that contained the easy-install.py also contained a folder pkg_resources, and i have copy-pasted this folder into the same folder where my pip-script.py script was (python27\Scripts). Since then, I found it in the python27\Lib\site-packages\pip-9.0.1-py2.7.egg\pip\_vendor folder as well, it might be a better solution to modify the pip-script.py file to import this.

很多答案都推荐以下方法，但是如果你通读了脚本的源代码，你就会发现它已经被弃用了。

wget https://bootstrap.pypa.io/ez_setup.py -O - | python

如果你的pip也坏了，这也没用。

pip install setuptools

我发现我必须运行确保pip、setuptools和wheel是最新的命令，以使pip重新工作。

python -m pip install --upgrade pip setuptools wheel

就我而言，我做到了:

pip install -U poetry

只需重新安装setuptools:

$ sudo wget https://pypi.python.org/packages/source/s/setuptools/setuptools-0.6c11.tar.gz#md5=7df2a529a074f613b509fb44feefefe74e
$ tar -zxvf setuptools-0.6c11.tar.gz
$ cd setuptools-0.6c11/
$ sudo python setup.py build
$ sudo python setup.py install
$ sudo pip install --upgrade setuptools

那么一切都会好起来的。