哪个和类型在virtualenv中显示IPython可执行文件的不同路径，在IPython中导入失败，在标准解释器中导入成功？ 无论哪个说了什么，它都执行/usr/local/bin/ipython

为什么

哪个

和

类型

指向不同的路径？为什么，如果我的virtualenv中安装了IPython，那么系统IPython会被执行，即使我的

$PATH

的顺序表明不是这样？在任何情况下，

import-novaclient

为什么会突然出现一个非常奇怪的错误

---

编辑 来自错误会话的pythonpath

（myvirtualenv）[~]sam@iota$ipython-c'导入系统；系统路径“

Python 2.7.5 (default, Sep  6 2013, 17:51:18)
[GCC 4.2.1 Compatible Apple LLVM 4.2 (clang-425.0.24)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import novaclient
>>> print "all is well here"
all is well here
>>> exit()  

['/Users/sam/.virtualenvs/myvirtualenv/lib/python2.7/site-packages',
 '',
 '/usr/local/bin',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/setuptools-1.1-py2.7.egg',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.4.1-py2.7.egg',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python27.zip',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload',
 '/Library/Python/2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages/IPython/extensions']

成功会话中的pythonpath

（myvirtualenv）[~]sam@iota$python-c'导入系统；打印系统路径“

Python 2.7.5 (default, Sep  6 2013, 17:51:18)
[GCC 4.2.1 Compatible Apple LLVM 4.2 (clang-425.0.24)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import novaclient
>>> print "all is well here"
all is well here
>>> exit()  

['/Users/sam/.virtualenvs/myvirtualenv/lib/python2.7/site-packages',
 '',
 '/usr/local/bin',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/setuptools-1.1-py2.7.egg',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.4.1-py2.7.egg',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python27.zip',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload',
 '/Library/Python/2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages/IPython/extensions']

为什么哪个和类型指向不同的路径

如果您的shell对

ipython

的路径进行了散列，则

type

将在不搜索

$path

的情况下为您提供散列路径，而

将忽略散列路径并进行搜索

假设您的shell是
bash
，则
hash
命令（不带参数）将显示哈希路径，或者您可以查看
bash\u CMDS
关联数组。但是您已经知道，
ipython
是散列的，因为
type
刚刚告诉您

通常，您可以通过使用
hash-r
命令（在不重新启动任何其他命令的情况下擦除缓存）或
hash-d ipython
（从缓存中仅移除
ipython
，但确保缓存中没有，例如
python
）来修复此问题。对于不同的shell，这两个命令可能不同（例如，在*csh和zsh中，分别是
rehash
和
rehash ipython
），但启动新shell应该始终有效

有关更多详细信息，请参阅bash参考手册中的，或系统上的
bash（1）
manpage，或者如果您使用谷歌搜索“bash哈希缓存”（like）之类的内容，将显示许多易于理解的博客文章

为什么，如果我的virtualenv中安装了IPython，那么系统IPython会被执行

如果shell对
ipython
的路径进行了散列，则
ipython
将从散列路径运行，而不搜索
$path

同样，启动一个新的shell等，应该可以解决这个问题

在任何情况下，为什么导入novaclient会出现一个看起来非常奇怪的错误

最有可能的是，它从您的环境中获得了
PYTHONPATH
，这导致venv的站点包和dist包成为系统Python的包，而这些位置的包与系统Python不兼容

您可以通过打印出
sys.path
来验证这一点。但它抱怨
/Users/sam/.virtualenvs/myvirtualenv/lib/python2.7/site packages/
中的文件，这意味着该路径必须位于
sys.path
上。而且（因为您是从不同的目录运行的）不仅仅是因为默认的
正在拾取它，而是因为它显式地在那里。所以，
sys.path
能告诉你的只是它是绝对路径还是相对路径。
回答得好，谢谢。你所说的
它一定正在发生是什么意思？@smlstvnh：我的意思是，这条路径一定以某种方式进入了
系统路径。重读一遍，你是对的，它不是很清楚。我会解决这个问题，谢谢你指出。对于像超级用户这样的网站来说，这可能是一个更好的问题，因为我认为问题最终与virtualenv或bash无关。但我不确定在你真正知道答案之前，没有办法知道这一点（无论是对于OP，还是对于未来有类似问题的搜索者）。
Python 2.7.5
Type "copyright", "credits" or "license" for more information.

IPython 1.1.0 -- An enhanced Interactive Python.

In [1]: import novaclient
In [2]: print "all is well here"
all is well here

(myvirtualenv)[~] sam@iota $ echo $PATH
 /Users/sam/.virtualenvs/myvirtualenv/bin:/usr/local/sbin:/usr/local/lib:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin
(myvirtualenv)[~] sam@iota $ python

Python 2.7.5 (default, Sep  6 2013, 17:51:18)
[GCC 4.2.1 Compatible Apple LLVM 4.2 (clang-425.0.24)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import novaclient
>>> print "all is well here"
all is well here
>>> exit()  

['/Users/sam/.virtualenvs/myvirtualenv/lib/python2.7/site-packages',
 '',
 '/usr/local/bin',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/setuptools-1.1-py2.7.egg',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.4.1-py2.7.egg',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python27.zip',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload',
 '/Library/Python/2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages/IPython/extensions']

['',
 '/Users/sam/.virtualenvs/projectx-dev-2/bin',
 '/Users/sam/.virtualenvs/projectx-dev-2/src/pyrax',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python27.zip',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python2.7',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python2.7/plat-darwin',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python2.7/plat-mac',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python2.7/plat-mac/lib-scriptpackages',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python2.7/lib-tk',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python2.7/lib-old',
 '/Users/sam/.virtualenvs/projectx-dev-2/lib/python2.7/lib-dynload',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
 '/usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
 '/Users/sam/.virtualenvs/myvirtualenv/lib/python2.7/site-packages',
 '/Users/sam/.virtualenvs/myvirtualenv/lib/python2.7/site-packages/IPython/extensions']