Bash is the GNU Project's Bourne Again SHell
An interactive shell with Bourne shell syntax (/bin/sh);
It is intended to conform to the IEEE POSIX P1003.2/ISO 9945.2 Shell and
Tools standard.  It includes the following features:
interactive command line editing, job control on architectures that support it,
Korn shell (ksh) features, Csh-like history features and brace expansion,
history and command re-entry, job control, shell functions and aliases,
arrays, arithmetic, ANSI-C quoting, tilde expansion, brace expansion,
substring capabilities, indirect variable expansion, expanded i/o capabilities,
control of builtin commands, help, shell optional behavior, prompt
customization, security, directory stack, POSIX mode, internationalization,
and command timing.

For more information on the features of Bash that are new to this type
of shell, see the file `documentation/features.texi'.
There is also a processed DVI file there, as well as a large man page.

WWW: http://www.gnu.org/software/bash/
     http://cnswww.cns.cwru.edu/~chet/bash/bashtop.html