GNU Bourne Again SHell

 Bash is an sh-compatible command language interpreter that executes
 commands read from the standard input or from a file. Bash also
 incorporates useful features from the Korn and C shells (ksh and csh).
 .
 Bash is ultimately intended to be a conformant implementation of the
 IEEE POSIX Shell and Tools specification (IEEE Working Group 1003.2).
 .
 The Programmable Completion Code, by Ian Macdonald, is now found in
 the bash-completion package.