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.

如果您正在使用bash(在Mac或GNU/Linux发行版上)，请将此添加到~/.bashrc中

export PYTHONPATH="${PYTHONPATH}:/my/other/path"

为了添加awesomo的答案，你也可以在~/中添加这一行。Bash_profile或~/.profile

下面的脚本可以在所有平台上运行，因为它是纯Python。它使用了pathlib路径(请参阅https://docs.python.org/3/library/pathlib.html)，使其能够跨平台工作。运行一次，重新启动内核，就完成了。灵感来自https://medium.com/@arnaud.bertrand/ modiing-python-s - sear-path-with-pth -files-2a41a4143574。为了运行它，它需要管理员权限，因为你修改了一些系统文件。

from pathlib import Path
to_add=Path(path_of_directory_to_add)
from sys import path

if str(to_add) not in path:
    minLen=999999
    for index,directory in enumerate(path):
        if 'site-packages' in directory and len(directory)<=minLen:
            minLen=len(directory)
            stpi=index
            
    pathSitePckgs=Path(path[stpi])
    with open(str(pathSitePckgs/'current_machine_paths.pth'),'w') as pth_file:
        pth_file.write(str(to_add))

修复从bash切换到zsh时Python路径问题

当我从bash切换到zsh时，我遇到了Python路径问题。

解决办法很简单，但我没有注意到。

Pip告诉我，脚本blah blah或包blah blah安装在~/。不在路径中的本地/bin。

在阅读了这个问题的一些解决方案后，我打开我的.zshrc，发现解决方案已经存在。

我不得不取消注释一行:

看一看

在MacOS上，而不是给出特定库的路径。给出根项目文件夹的完整路径

~/.bash_profile 

让我很开心，例如:

export PYTHONPATH="${PYTHONPATH}:/Users/<myuser>/project_root_folder_path"

这样做之后:

source ~/.bash_profile