The Bash Shell
bash is the GNU Project implementation of the standard Unix shell sh. Since the original sh was the “Bourne shell,” bash is the “Bourne again shell”. As the bash home page says:
Bash is an sh-compatible shell that incorporates useful features from the Korn shell (ksh) and C shell (csh). It is intended to conform to the IEEE POSIX P1003.2/ISO 9945.2 Shell and Tools standard. It offers functional improvements over sh for both programming and interactive use.
While there are a number of shells available to choose from on a Linux system, bash is very popular and powerful, and it is the default shell for new accounts. Bash has become popular enough that it is available on many other Unix flavors as well, including Sun’s Solaris and Hewlett-Packard’s HP/UX. Exam 102 concentrates on its use and configuration. The next few sections deal with common shell concepts, but the examples are specific to bash.