问题
我想创建一个虚拟环境（$ python3 -m venv venv），每次看到pip list都给我20版本。
症状
创建虚拟环境时，我得到了过时的pip ...
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ python3 -m venv venv
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ source venv/bin/activate
(venv) ╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ pip list
DEPRECATION: The default format will switch to columns in the future. You can use --format=(legacy|columns) (or define a format=(legacy|columns) in your pip.conf under the [list] section) to disable this warning.
pip (9.0.1)
pkg-resources (0.0.0)
setuptools (39.0.1)
所以，我调查了本地软件包
(venv) ╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ python3
>>> import os
>>> ... import site
>>> ... print(site.getsitepackages())
>>> ... os.listdir(site.getsitepackages()[0])
['/usr/local/lib/python3.6/dist-packages', '/usr/lib/python3/dist-packages', '/usr/lib/python3.6/dist-packages']
然后我在本地文件系统中查看pip的内容
(venv) ╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ deactivate 127 ↵
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ python3 -m pip install -U pip
Defaulting to user installation because normal site-packages is not writeable
Requirement already up-to-date: pip in /home/mat/.local/lib/python3.6/site-packages (20.0.2)
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ ll /usr/local/lib/python3.6/dist-packages | grep 'pip'
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ ll /usr/lib/python3.6/dist-packages | grep 'pip' 1 ↵
ls: cannot access '/usr/lib/python3.6/dist-packages': No such file or directory
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ ll /usr/lib/python3/dist-packages | grep 'pip' 1 ↵
drwxr-xr-x 11 root root 4.0K Mar 5 14:07 pip
drwxr-xr-x 2 root root 4.0K Mar 5 14:07 pip-9.0.1.egg-info
现在我检查pip的版本
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ pip --version
pip 20.0.2 from /home/mat/.local/lib/python3.6/site-packages/pip (python 3.6)
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ pip3 --version
pip 20.0.2 from /home/mat/.local/lib/python3.6/site-packages/pip (python 3.6)
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ ll /home/mat/.local/lib/python3.6/site-packages/pip
total 20K
-rw-r--r-- 1 mat mat 455 Mar 14 11:30 __init__.py
drwxr-xr-x 13 mat mat 4.0K Mar 14 11:30 _internal
-rw-r--r-- 1 mat mat 632 Mar 14 11:30 __main__.py
drwxr-xr-x 2 mat mat 4.0K Mar 14 11:30 __pycache__
drwxr-xr-x 19 mat mat 4.0K Mar 14 11:30 _vendor
因此，您可以看到python3 -m venv venv看上去/usr/lib/python3/dist-packages，而pip3 --version看上去/home/mat/.local/lib/python3.6/site-packages/pip
问题＃1
如何配置 python3 ，这样当我输入python3 -m venv venv然后激活虚拟环境时，我可以输入pip list并看到版本20，就像我离开虚拟环境？
问题2
我认为因为输入pip --version并显示版本20，所以在创建虚拟环境时它也应该具有版本20。为什么不是这样？
问题3
以下输出显示pip版本9：
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ ll /usr/lib/python3/dist-packages | grep 'pip' 1 ↵
drwxr-xr-x 11 root root 4.0K Mar 5 14:07 pip
drwxr-xr-x 2 root root 4.0K Mar 5 14:07 pip-9.0.1.egg-info
那么，为什么下面的命令没有将/usr/lib/python3/dist-packages更改为版本20？
╭─mat@superelectron ~/code/mist-alpha ‹cassandra-api*›
╰─$ python3 -m pip install -U pip
Defaulting to user installation because normal site-packages is not writeable
Requirement already up-to-date: pip in /home/mat/.local/lib/python3.6/site-packages (20.0.2)