python - 为什么virtualenv从我的shell继承$ PYTHONPATH？

所以我在Ubuntu 14.04机器上将我的所有工具从python2迁移到python3.4。到目前为止，我已经完成了以下工作：

在我的zshrc中将python别名为python3，仅用于我的用户
在系统本身上安装了pip3（但是我只是使用virtualenvs来解决所有问题，所以我不会真正使用它）。
改变了我的virtualenvwrapper＆＃34; make＆＃34; mkvirtualenv --python=/usr/bin/python3的别名（＆＃39; workon＆＃39;在下面调用＆＃39; v＆＃39;）

现在好奇，你可以清楚地看到它，从virtualenv激活的环境运行python3仍然继承我的$ PYTHONPATH，它仍然为我所有的python2路径设置。这在我的virtualenv中安装/运行程序时会造成严重破坏，因为python3路径显示在旧的python2路径之后，因此python2模块首先在我的程序中导入。把我的$ PYTHONPATH解压缩到＆＃39;＆＃39;在启动virtualenv之前修复此问题，我的程序按预期启动。但我的问题是：

virtualenvs中$ PYTHONPATH的继承是否正常？那不是打败了整个目的吗？
为什么当python已经在内部处理它自己的路径时，将$ PYTHONPATH设置为shell中的env-var？
我正确使用$ PYTHONPATH吗？我应该在我的zshrc＆＃39;中设置它吗？仅列出我的个人添加内容（$ HOME / dev），而不是冗余的＆＃39; / usr / local / lib /＆＃39;地点？
我可以很容易地在调用它们之前导出备用的python3路径以供我的virtualenvs使用，并在完成后重置它们，但这是解决此问题的最佳方法吗？

    ○ echo $PYTHONPATH
    /usr/local/lib/python2.7/site-packages:/usr/local/lib/python2.7/dist-packages:/usr/lib/python2.7/dist-packages:/home/brian/dev

    brian@zeus:~/.virtualenvs
    ○ python2
    Python 2.7.6 (default, Mar 22 2014, 22:59:56)
    [GCC 4.8.2] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import sys, pprint
    >>> pprint.pprint(sys.path)
    ['',
     '/usr/local/lib/python2.7/dist-packages/pudb-2013.3.4-py2.7.egg',
     '/usr/local/lib/python2.7/dist-packages/Pygments-1.6-py2.7.egg',
     '/usr/local/lib/python2.7/dist-packages/urwid-1.1.1-py2.7-linux-x86_64.egg',
     '/usr/local/lib/python2.7/dist-packages/pythoscope-0.4.3-py2.7.egg',
     '/usr/local/lib/python2.7/site-packages',
     '/usr/local/lib/python2.7/dist-packages',
     '/usr/lib/python2.7/dist-packages',
     '/home/brian/dev',
     '/usr/lib/python2.7',
     '/usr/lib/python2.7/plat-x86_64-linux-gnu',
     '/usr/lib/python2.7/lib-tk',
     '/usr/lib/python2.7/lib-old',
     '/usr/lib/python2.7/lib-dynload',
     '/usr/lib/python2.7/dist-packages/PILcompat',
     '/usr/lib/python2.7/dist-packages/gst-0.10',
     '/usr/lib/python2.7/dist-packages/gtk-2.0',
     '/usr/lib/pymodules/python2.7',
     '/usr/lib/python2.7/dist-packages/ubuntu-sso-client',
     '/usr/lib/python2.7/dist-packages/ubuntuone-client',
     '/usr/lib/python2.7/dist-packages/ubuntuone-storage-protocol',
     '/usr/lib/python2.7/dist-packages/wx-2.8-gtk2-unicode']
    >>>

    brian@zeus:~/.virtualenvs
    ○ v py3venv
    (py3venv)
    brian@zeus:~/.virtualenvs
    ○ python3
    Python 3.4.0 (default, Apr 11 2014, 13:05:11)
    [GCC 4.8.2] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import sys, pprint
    >>> pprint.pprint(sys.path)
    ['',
     '/usr/local/lib/python2.7/site-packages',
     '/usr/local/lib/python2.7/dist-packages',
     '/usr/lib/python2.7/dist-packages',
     '/home/brian/dev',
     '/home/brian/.virtualenvs/py3venv/lib/python3.4',
     '/home/brian/.virtualenvs/py3venv/lib/python3.4/plat-x86_64-linux-gnu',
     '/home/brian/.virtualenvs/py3venv/lib/python3.4/lib-dynload',
     '/usr/lib/python3.4',
     '/usr/lib/python3.4/plat-x86_64-linux-gnu',
     '/home/brian/.virtualenvs/py3venv/lib/python3.4/site-packages']
    >>>
    (py3venv)

为什么virtualenv从我的shell继承$ PYTHONPATH？

3 个答案: