Some of Bash's programming features are shared by all other Bourne-style, POSIX-compatible Shell scripting languages. These are specified by the POSIX standard, in section 2, Shell Command Language. Bash is designed to conform to this standard. You can read what it specifies at http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html.
Bash also has many other features that are not described in the POSIX shell script standard that make many common shell script programming tasks easier. In this book, we will examine both categories.
