当我跑步时

import sys 
print sys.path

在Mac上（Mac OS X 10.6.5，Python 2.6.1），我得到以下结果。

/Library/Python/2.6/site-packages/ply-3.3-py2.6.egg
...
/Library/Python/2.6/site-packages/ipython-0.10.1-py2.6.egg
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python26.zip
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/plat-darwin
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/plat-mac
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/plat-mac/lib-scriptpackages

/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-tk
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-old
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-dynload
/Library/Python/2.6/site-packages
/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/PyObjC
/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/wx-2.8-mac-unicode

它们分为5类。

• /Library/Python/2.6/site-packages/*.egg
• /Library/Python/2.6/site-packages
• 框架/Python.framework/版本/2.6/lib/python2.6
• 框架/Python.framework/版本/2.6/Extras/lib/python
• 来自PYTHONPATH环境变量的PATH。

我可以使用代码添加更多路径

sys.path.insert(0, MORE_PATH)

• 什么例程设置这些路径，何时设置？
• 是否有些路径是在python源代码中构建的？
• 插入’sys.path.insert’的路径是否有可能被忽略？我对此感到很好奇，就像使用mod_wsgi一样，我发现使用sys.path.insert找不到路径。

添加

根据迈克尔的回答，我查看了site.py，并获得了以下代码。

def addsitepackages(known_paths):
    """Add site-packages (and possibly site-python) to sys.path"""
    sitedirs = []
    seen = []

    for prefix in PREFIXES:
        if not prefix or prefix in seen:
            continue
        seen.append(prefix)

        if sys.platform in ('os2emx', 'riscos'):
            sitedirs.append(os.path.join(prefix, "Lib", "site-packages"))
        elif sys.platform == 'darwin' and prefix == sys.prefix:
            sitedirs.append(os.path.join("/Library/Python", sys.version[:3], "site-packages"))

我还认为，具有site.py的目录名称（对于我的Mac是/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6）应该内置到Python源代码中。