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Unit 8: Shell

Several shells are available for Linux including: notes

shell name Developed by where remark
BASH ( Bourne- Brian Fox and Chet Free Software Most common shell in Linux. It’s
Again SHell ) Ramey Foundation Freeware shell.
CSH (C SHell) Bill Joy University of The C shell’s syntax and usage are
California (For BSD) very similar to the C programming
language.
KSH (Korn SHell) David Korn AT & T Bell Labs —
TCSH See the man page. — TCSH is an enhanced but
Type $ man tcsh completely compatible version of
the Berkeley UNIX C shell (CSH).
To find all of the available shells in your system, type the following command:

$ cat /etc/shells
Each shell does the same job, but each understands different command syntax and provides
different built-in functions.

Did u know? What is shell?

8.1 Different types of shells

8.1.1 BasH (Bourne-again shell)

Bash is a free software UNIX shell written for the GNU Project. Its name is an acronym which
stands for Bourne-again shell. The name is a pun on the name of the Bourne shell (sh), an early
and important Unix shell written by Stephen Bourne and distributed with Version 7 Unix circa
1978, and “born again”. Bash was created in 1987 by Brian Fox. In 1990 Chet Ramey became the
primary maintainer.
Bash is the default shell on most systems built on top of the Linux kernel as well as on Mac OS
X and it can be run on most Unix-like operating systems. It has also been ported to Microsoft
Windows using Subsystem for UNIX-based Applications (SUA), or POSIX emulation provided
by Cygwin and MSYS. It has been ported to MS-DOS by the DJGPP project and to Novell
NetWare.

8.1.2 c shell (csh)

The C shell (csh) is a Unix shell developed by Bill Joy for the BSD Unix system. It was originally
derived from the 6th Edition Unix /bin/sh (which was the Thompson shell), the predecessor of
the Bourne shell. Its syntax is modeled after the C programming language. The C shell added
many feature improvements over the Bourne shell, such as aliases and command history. Today,
the original C shell is not in wide use on Unix; it has been superseded by other shells such as
the Tenex C shell (tcsh) based on the original C shell code, but adding filename completion and
command line editing, features later copied in the Korn shell (ksh), and the GNU Bourne-Again
shell (bash). An independently-developed and modernized C shell, created by Nicole Hamilton,
also survives on Windows in the form of Hamilton C shell.

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