Search Path Variations

This description of the module search path is accurate, but generic; the exact configuration of the search path is prone to changing across platforms and Python releases. Depending on your platform, additional directories may automatically be added to the module search path as well.

For instance, Python may add an entry for the current working directory—the directory from which you launched your program—in the search path after the PYTHONPATH directories, and before the standard library entries. When you’re launching from a command line, the current working directory may not be the same as the home directory of your top-level file (i.e., the directory where your program file resides). Because the current working directory can vary each time your program runs, you normally shouldn’t depend on its value for import purposes. See Chapter 3 for more on launching programs from command lines.[49]

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To see how your Python configures the module search path on your platform, you can always inspect sys.path—the topic of the next section.