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!