Programming Python, 4th Edition

Chapter 4. File and Directory Tools

“Erase Your Hard Drive in Five Easy Steps!”

This chapter continues our look at system interfaces in Python by focusing on file and directory-related tools. As you’ll see, it’s easy to process files and directory trees with Python’s built-in and standard library support. Because files are part of the core Python language, some of this chapter’s material is a review of file basics covered in books like Learning Python, Fourth Edition, and we’ll defer to such resources for more background details on some file-related concepts. For example, iteration, context managers, and the file object’s support for Unicode encodings are demonstrated along the way, but these topics are not repeated in full here. This chapter’s goal is to tell enough of the file story to get you started writing useful scripts.

File Tools

External files are at the heart of much of what we do with system utilities. For instance, a testing system may read its inputs from one file, store program results in another file, and check expected results by loading yet another file. Even user interface and Internet-oriented programs may load binary images and audio clips from files on the underlying computer. It’s a core programming concept.

In Python, the built-in open function is the primary tool scripts use to access the files on the underlying computer system. Since this function is an inherent part of the Python language, you may already be familiar with its basic workings. When called, the ...