Teach Yourself Unix, Third Edition, would serve the reader better if it used different section-titling conventions. For example, "Using the -R Option with Ls" tells the reader nothing; something like "Listing Files in Subdirectories," which is what the -R switch is used for, would be better.
This book also suffers from some production problems. The sections about cc, the C compiler, consistently call the program Cc in their headings. The command ls gets called Ls in headings. Though this clearly is the work of a publishing package that puts headings into title case, Unix is case-sensitive and typing Cc in place of cc or Ls in place of ls will usually cause an error.