Bourne Again Shell

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What Does Bourne Again Shell Mean?

Bourne again shell (Bash) is a free Unix shell that can be used in place of the Bourne shell. It is a complete implementation of the IEEE Portable Operating System Interface for Unix (POSIX) and Open Group shell specification.


Bash is basically a command processor that typically runs in a text window, allowing the user to type commands that cause actions. It can read commands from a file, called a script. Like all Unix shells it supports the following:

  • File name wildcarding
  • Piping
  • Hear documents
  • Command execution
  • Variables and control structures for condition testing and iteration

Techopedia Explains Bourne Again Shell

Bash was written for the GNU Project by Brian Fox. It is called Bourne again shell for many reasons, the first being that it is the open-source version of the Bourne shell and the second as a pun on the concept of being born again. Its acronym is also a description of what the project did, which was to bash together sh, csh, and ksh features.

A Unix shell is a command-line interpreter that provides users with a basic user interface. It allows users to communicate with the system through a series of commands that are typed in the command-line window. There are no buttons or pop-up windows in a shell, simply lots and lots of text.

Essentially, Bash allows users of Unix-like systems to control the innermost components of the operating system using text-based commands.

Bash has a number of extensions and runs on Unix-like operating systems like Linux and Mac OS X. It was ported to Windows through the Subsystem for UNIX-based Applications (SUA) and by POSIX emulation using Cygwin or MSYS. It can even be used in MS-DOS.


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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.