为了给出更多的解释，Python将使用site.py脚本(通常位于sys. py中)自动构造它的搜索路径(如上所述和这里)。Prefix + lib/python<version>/site-packages以及lib/site-python)。可以获取sys.prefix的值:

python -c 'import sys; print(sys.prefix)'

The site.py script then adds a number of directories, dependent upon the platform, such as /usr/{lib,share}/python<version>/dist-packages, /usr/local/lib/python<version>/dist-packages to the search path and also searches these paths for <package>.pth config files which contain specific additional search paths. For example easy-install maintains its collection of installed packages which are added to a system specific file e.g on Ubuntu it's /usr/local/lib/python2.7/dist-packages/easy-install.pth. On a typical system there are a bunch of these .pth files around which can explain some unexpected paths in sys.path:

python -c 'import sys; print(sys.path)'

因此，可以创建一个.pth文件，并将其放在这些目录中的任何一个目录中(包括上面提到的sitedir)。这似乎是大多数包被添加到系统的方式。而不是使用PYTHONPATH。

Note: On OSX there's a special additional search path added by site.py for 'framework builds' (but seems to work for normal command line use of python): /Library/Python/<version>/site-packages (e.g. for Python2.7: /Library/Python/2.7/site-packages/) which is where 3rd party packages are supposed to be installed (see the README in that dir). So one can add a path configuration file in there containing additional search paths e.g. create a file called /Library/Python/2.7/site-packages/pip-usr-local.pth which contains /usr/local/lib/python2.7/site-packages/ and then the system python will add that search path.

对我来说，当我更改.bash_profile文件时，它起作用了。只是改变.bashrc文件工作，直到我重新启动shell。

对于python 2.7，它应该是这样的:

export PYTHONPATH="$PYTHONPATH:/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python"

在.bash_profile文件的末尾。

这适用于Windows

在Windows上，使用Python 2.7进入Python安装文件夹。 开放的Lib /网站。 将example.pth空文件添加到此文件夹。 将所需的路径添加到文件中，每行一个。

然后，您将能够从脚本中看到这些路径中的所有模块。

在Mac上:

user@terminal$ env PYTHONPATH=module_path python3
>>> import sys
>>> sys.path
['module_path', 'plus_other_python3_paths',...]

这是对这个线程的更新，它有一些旧的答案。

对于那些使用MAC-OS Catalina或更新版本(>= 10.15)的用户，它引入了一个名为zsh的新终端(旧bash的替代品)。

由于这个更改，我在上面的回答中遇到了一些问题，我通过创建文件~/来解决一些问题。并将文件目录粘贴到$PATH和$PYTHONPATH

所以，首先我做了:

nano ~/.zshrc

当编辑器打开时，我粘贴以下内容:

export PATH="${PATH}:/Users/caio.hc.oliveira/Library/Python/3.7/bin"
export PYTHONPATH="${PYTHONPATH}:/Users/caio.hc.oliveira/Library/Python/3.7/bin"

保存，并重新启动终端。

重要提示:上面的路径设置为我的计算机的路径，你必须适应你的python。

A <-> B之间的最短路径是一条直线;

import sys
if not 'NEW_PATH' in sys.path:
  sys.path += ['NEW_PATH']