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Programming Python, Second Edition by Mark Lutz

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System Scripting Overview

The next two sections will take a quick tour through sys and os, before this chapter moves on to larger system programming concepts. As I’m not going to demonstrate every item in every built-in module, the first thing I want to do is show you how to get more details on your own. Officially, this task also serves as an excuse for introducing a few core system scripting concepts -- along the way, we’ll code a first script to format documentation.

Python System Modules

Most system-level interfaces in Python are shipped in just two modules: sys and os. That’s somewhat oversimplified; other standard modules belong to this domain too (e.g., glob, socket, thread, time, fcntl), and some built-in functions are really system interfaces as well (e.g., open). But sys and os together form the core of Python’s system tools arsenal.

In principle at least, sys exports components related to the Python interpreter itself (e.g., the module search path), and os contains variables and functions that map to the operating system on which Python is run. In practice, this distinction may not always seem clear-cut (e.g., the standard input and output streams show up in sys, but they are at least arguably tied to operating system paradigms). The good news is that you’ll soon use the tools in these modules so often that their locations will be permanently stamped on your memory.[9]

The os module also attempts to provide a portable programming interface to the underlying operating system ...

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