Linux Shell Scripting

Linux Shell Scripting training | KR Network Cloud

Shell script defined as: “Shell Script is series of command written in plain text file. Shell script is just like batch file is MS-DOS but have more power than the MS-DOS batch file.”

Normally shells are interactive. It means shell accept command from you (via keyboard) and execute them. But if you use command one by one (sequence of 'n' number of commands), then you can store this sequence of command to text file and tell the shell to execute this text file instead of entering the commands. This is known as shell script.

Linux Shell Scripting Course Objective

Shell scripts can be used to prepare input files, job monitoring, and output processing.

Useful to create own commands.
Save lots of time on file processing.
To automate some task of day to day life.
System Administration part can be also automated.
A working knowledge of shell scripting is essential to everyone wishing to become
reasonably adept at system administration, even if they do not anticipate ever having to actually write a script.
Writing shell scripts is not hard to learn, since the scripts can be built in bite-sized sections and there is only a fairly small set of shell-specific operators and options to learn.
The syntax is simple and straightforward, similar to that of invoking and chaining together utilities at the command line, and there are only a few "rules" to learn.
A shell script is a "quick and dirty" method of prototyping a complex application

Course Content Of Linux Shell Scripting

+ Unit-1 Introduction

Shells
Types of Unix Shells
Advantages of Shell Scripts

+ Unit-2 Bash Basics

Initialization Files
Login Shells, Non-Login Shells
Aliases, Variables
Working with Variables
Important Internal Bash Variables
Command History
Input and Output Channels
Redirection to Files
The here Operator
Feeding Output to Another Process
Duplicating the Output with tee
Types of Commands
Quoting
Substitution and Expansion
Variable Substitution
Filename Expansion(File Globbing)
Command & Arithmetic Substitution
Command-Line Interpretation
Command Separators

+ Unit-3 Basic Script Elements 1(Input, Output)

Program Flow Charts
General Considerations
Producing Output From a Script
Reading User Input
Simple Operation with Variables
Basic Strings Operation
Arithmetic Operations
Regular Expressions

+ Unit-4 Basic Script Elements 2(Control Structures)

Simple Branching With if
Short Form of if
Multiple Branch with case
Iterations and Loops
Looping with while and until
Processing a List with for
Exiting From a Loops
Exiting from the Current Loop
Iteration with continue
Exiting from the Loop with break

+ Unit-5 Advanced Scripting Techniques

Reading input with read
Shell Functions
Reading Options with getopts
Signal Handling with trap
Implementing Simple Menus with select
Dialog Boxes with dialog
Yes/No Box(yesno)
Message Box(msgbox)
Input Box(input box)
Text Box(text box)
Menu Box(menu)
Check List Box(checklist)
Radio List Box(radio list)
progress Meter Box(gauge)

+ Unit-6 Useful utilities for Shell Scripts

cat
cut
date
grep
egrep
fgrep
sed
test
tr
awk
Sort
uniq
Special Variable Substitution Operators for Bash
Debugging Shell ScriptsSample ScriptsBottom of Form

Why Learn Linux Shell Scripting?

What is Shell?

It is a command language interpreter that executes commands read from the standard input device such as keyboard or from a file.
The shell gets started when you log in or open a console (terminal).
Quick and dirty way to execute utilities.

The shell is not part of system kernel, but uses the system kernel to execute programs, create files etc.

What is Kernel?

Kernel is hart of Linux Os.
It manages resource of Linux Os. Resources means facilities available in Linux. For e.g. Facility to store data, print data on printer, memory, file management etc.
Kernel decides who will use this resource, for how long and when. It runs your programs (or set up to execute binary files).
The kernel acts as an intermediary between the computer hardware and various programs/application/shell.