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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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
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
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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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
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
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
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
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
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
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.
www.edureka.co
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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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Bash vs C Shell vs Korn Shell | Edureka

  • 2.
    THE KERNEL &THE SHELL EVOLUTION OF THE SHELL WHICH SHELL IS FOR YOU? SH=BASH? www.edureka.co SHELL vs BASH vs OTHER LINUX SHELLS
  • 3.
  • 4.
    The computer programsthat 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? www.edureka.co Applications Kernel Memory DevicesCPU
  • 5.
    The Shell isa 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? www.edureka.co Translates Commands Language understood by the Kernel Takes Input From User
  • 6.
    The basic conceptof 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? www.edureka.co Translates Commands Language understood by the Kernel Takes Input From User
  • 7.
  • 8.
    Created by StephenBourne, 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 www.edureka.co sh 1977
  • 9.
    The C shellwas 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 www.edureka.co csh 1978
  • 10.
    Developed by DavidKorn, 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 www.edureka.co ksh 1983
  • 11.
    Started out asa derivative of the C Shell but with a programmable command line completion and editing features added to it. TENEX C Shell www.edureka.co tcsh 1983
  • 12.
    One of themost 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 www.edureka.co bash 1989
  • 13.
    Many shells wereevolved 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. www.edureka.co pdksh 1989 ash 1989rc 1989 Other Shells
  • 14.
    Other Shells www.edureka.co zsh 1990 POSIX 1992 es 1993 scsh 1994 dash 1996 psh 1999 mksh 2003 Manyshells 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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  • 16.
    www.edureka.co SHELL SCRIPT The ShellCommand 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.
  • 17.
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  • 19.
    www.edureka.co C Shell Ideal forlearners 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
  • 20.