These files are the examples from Efficient Linux at the Command Line by Daniel J. Barrett. With these files on your Linux computer, you'll can easily run the book's sample commands exactly as written. Just cd to the appropriate directory and run the commands. The example files are organized by chapter and section.

For example, before running the sample commands in chapter 2, run cd ch02. Then look for a subdirectory whose purpose matches the section of the book you're reading. The files for the section "Pattern Matching for Filenames" are in the subdirectory pattern_matching_for_filenames, and so on.

Have fun!