linux shell programming tutorial

Linux Shell Scripting Tutorial Ver. 1.0

Written by Vivek G Gite

I N D E X

Introduction

Kernel❍

Shell❍

How to use Shell❍

Common Linux Command Introduction❍

Redirectors❍

Pipes❍

Filters❍

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Shell Programming

Variables in Linux❍

How to define User defined variables❍

Rules for Naming variable name❍

How to print or access value of UDV (User defined variables)❍

How to write shell script❍

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Why Command Line arguments required❍

Exit Status❍

Filename Shorthand or meta Characters (i.e. wild cards)❍

Programming Commands

echo command❍

Decision making in shell script ( i.e. if command)❍

test command or [ expr ]❍

Loop in shell scripts❍

The case Statement❍

The read Statement❍

Functions❍

User Interface and dialog utility❍

trap command❍

getopts command❍

More examples of Shell Script (Exercise for You :-)❍

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Introduction

This tutorial is designed for beginners only and This tutorial explains the basics of

shell programming by showing some examples of shell programs. Its not help or

editor like vi or mcedit and login to your system. Before Starting Linux Shell Script

Programming you must know

Kernel

●

Shell●

Process●

Redirectors, Pipes, Filters etc.●

What's Kernel

Kernel is hart of Linux O/S. It manages resource of Linux O/S. Resources means

facilities available in Linux. For eg. Facility to store data, print data on printer,

Device management●

File management●

Memory management●

What's Linux Shell

Computer understand the language of 0's and 1's called binary language, In early

days of computing, instruction are provided using binary language, which is difficult

for all of us, to read and write. So in O/s there is special program called Shell. Shell

accepts your instruction or commands in English and translate it into computers

native binary language.

This is what Shell Does for US

command line interface ( Usually in-front of $ prompt, This prompt is depend upon

your shell and Environment that you set or by your System Administrator,

therefore you may get different prompt ).

NOTE: To find your shell type following command

How to use Shell

To use shell (You start to use your shell as soon as you log into your system) you

have to simply type commands. Following is the list of common commands.

Linux Common Commands

NOTE that following commands are for New users or for Beginners only. The

help, since help of ls command is quite big that can't fit on single screen )

Syntax: command-name --help

Syntax: man command-name

Syntax: info command-name

See what happened when you type following

NOTE: In MS-DOS, you get help by using /? clue or by typing help command as