Chapter 1, What is Bash?, opens the book by giving a clear definition of what the Bash shell actually is, where it fits in with other programs on a Unix system, and how to find and (if necessary) install it on your system.
Chapter 2, Bash Command Structure, looks at the anatomy of Bash command lines, starting with simple single commands and arguments, and moves on through running multiple commands, and good quoting practices for data.
Chapter 3, Essential Commands, examines a list of common commands useful in Bash command lines and scripts, explaining the situations in which each is useful and how to use them; listing, searching, sorting, and slicing data are all discussed.
Chapter 4, Input, Output, and Redirection, extends our new basic command structure knowledge to show how to specify where data for commands to read comes from, and where it goes to—including "piping" one command's output into another command, and filtering it in between.
Chapter 5, Variables and Patterns, explains and demonstrates how Bash's variable assignment and expansion works for both simple variables and arrays, how to transform strings conveniently with parameter expansion, and how to use patterns to match and specify lists of files.
Chapter 6, Loops and Conditionals, shows how to run the same set of commands on every item of a list of shell words or lines, and how to run commands only if a certain expression is true or false.
Chapter 7, Scripts, Functions, and Aliases, builds on our new knowledge of shell grammar and common commands to start writing your own commands, implemented in the Bash programming language and executable from anywhere on your computer.
Chapter 8, Best Practices, ends the book with some important hints, tips, and techniques for writing robust and readable shell script that will set you on the path to becoming a true shell scripting expert.