What is Bourne again shell?
Bourne again shell (Bash) is a free Unix shell that replaces the Bourne Shell can be used. It is a full implementation of the IEEE Portable Operating System Interface for Unix (POSIX) and Open Group Shell specification.
Bash is basically a command processor, usually running in a text window, that allows the user to enter commands that cause actions. It can read commands from a file, a script. Like all Unix shells, it supports the following:
- Hear documents
- Command execution
- Variables and control structures for condition checking and iteration
Bash was written by Brian Fox for the GNU Project. It's called Bourne Shell for many reasons, the first being that it's the open source version of the Bourne Shell and the second as a pun on the concept of rebirth. Its acronym is also a description of what the project did, namely combining 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 entered in the command line window. There are no buttons or pop-up windows in a shell, just lots and lots of text.
Basically, 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 under Unix-like operating systems such as Linux and Mac OS X. It was ported to Windows via the subsystem for UNIX-based applications (SUA) and via POSIX emulation with Cygwin or MSYS. It can even be used in MS-DOS.