python的搜索路径

python

假设一个名为spam的模块被导入。
则python解释器的搜索路径：interpreter首先从built-in模块中搜索其名字spam。如果没有找到，则在sys.path中查找。而sys.path由以下位置初始化：

• 在script所在当前目录。
• the installation-dependent default.
• PYTHONPATH
  

  可以在python 环境下使用sys.path.append(path)添加相关的路径，但在退出python环境后自己添加的路径就会自动消失！
  Augment the default search path for module files. The format is the same as the shell’s PATH: one or more directory pathnames separated by os.pathsep (e.g. colons on Unix or semicolons on Windows). Non-existent directories are silently ignored.
  In addition to normal directories, individual PYTHONPATH entries may refer to zipfiles containing pure Python modules (in either source or compiled form). Extension modules cannot be imported from zipfiles.
  The default search path is installation dependent, but generally begins with prefix/lib/pythonversion (see PYTHONHOME above). It is always appended to PYTHONPATH.
  An additional directory will be inserted in the search path in front of PYTHONPATH as described above under Interface options. The search path can be manipulated from within a Python program as the variable sys.path.