** Linux Admin Certification Training: https://www.edureka.co/linux-admin ** This PPT talks about the origin and evolution of different Linux shells and draws a parallel between three of the most basic shells by a demonstration on the terminal. It also debunks a myth on the old "Shell vs Bash" along the way. In conclusion, it gives a little insight on which shells(or its extensions) are used for what purposes to help you choose the shell for yourself to suit your needs. The Kernel & the Shell Evolution of the Shell Sh=bash? Which Shell is for you? Shell vs Bash vs Other Check our complete Linux admin playlist here: https://goo.gl/ZUTGVb Follow us to never miss an update in the future. YouTube: https://www.youtube.com/user/edurekaIN Instagram: https://www.instagram.com/edureka_learning/ Facebook: https://www.facebook.com/edurekaIN/ Twitter: https://twitter.com/edurekain LinkedIn: https://www.linkedin.com/company/edureka

2. THE KERNEL & THE SHELL
EVOLUTION OF THE SHELL
WHICH SHELL IS FOR YOU?
SH=BASH?
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SHELL vs BASH vs OTHER LINUX SHELLS

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4. The computer programs that allocate the system resources and coordinate all the details of the computer's internals is
called the operating system or the Kernel. Users communicate with the OS through a program called the Shell.
What is a Kernel?
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Applications
Kernel
Memory DevicesCPU

5. The Shell is a Command Line Interpreter. It translates commands entered by the user and converts them into a language
that is understood by the Kernel.
What is a Shell?
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Translates
Commands
Language understood
by the Kernel
Takes Input
From User

6. The basic concept of a shell script is a list of commands, which are listed in the order of execution. A good shell script will
have comments, preceded by #sign, describing the steps
What is a Shell Script?
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Translates
Commands
Language understood
by the Kernel
Takes Input
From User

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8. Created by Stephen Bourne, the Bourne Shell is a useful shell even today and in some cases, as the default root shell. Its
grammar is very similar to the Algorithmic Language (ALGOL).
The Bourne shell had two primary goals: serve as a command interpreter and for scripting.
Bourne Shell
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sh
1977

9. The C shell was developed by Bill Joy with the objective of achieving a scripting language similar to C programming
language. This was useful given that C was a primary language in use back then which also made it easier and faster to use.
C Shell
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csh
1978

10. Developed by David Korn, the Korn Shell combined features of both Bourne Shell and C Shell. It is backward compatible with
the former.
It includes features from the C Shell such as job control, command aliasing & command history.
Korn Shell
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ksh
1983

11. Started out as a derivative of the C Shell but with a programmable command line completion and editing features added to
it.
TENEX C Shell
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tcsh
1983

12. One of the most widely used shell, today, it was written by Brian Fox for the GNU project as a pre software replacement for
the Bourne Shell. Shows all features from the Bourne shell but is much more efficient and easy to use.
It supports filename globbing, piping, command substitution, and control structures for conditional testing and iteration.
Bourne-Again Shell
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bash
1989

13. Many shells were evolved later such as Public Domain Korn Shell, Almquist Shell and the Extensible Shell bringing in new
features and dialects of their own suitable for different needs.
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pdksh
1989
ash
1989rc
1989
Other Shells

14. Other Shells
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zsh
1990
POSIX
1992
es
1993
scsh
1994
dash
1996
psh
1999 mksh
2003
Many shells were evolved later such as Public Domain Korn Shell, Almquist Shell and the Extensible Shell bringing in new
features and dialects of their own suitable for different needs.

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SHELL SCRIPT
The Shell Command Language is
a programming language
according to the POSIX
Standards.
It is a specification.
BASH
Bash is one of the many
implementations of the Shell
Command Language.

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C Shell
Ideal for learners
comfortable with the C
programming language.
Mostly Network Admins use
this shell. Korn Shell
This highly interactive shell is
generally used to to
automate a wide variety of
operating system and system
administration tasks.
Bourne Shell
Versatile and easy to learn,
most widely taught and
learnt shell for scripting and
interfacing purposes

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