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Bash Tutorial

Bash Scripting Tutorial

Part 1 - Bash Shell Scripting Basics

Introduction and Basics:

• Introduction
Bash Introduction. What is Bash? Bourne Again Shell.
• What is a Shell?
Internal and External Commands, Type command, Bash Configuration Files - Startup Files.
• Bash Shell Command Interpreter
Bash Command Interpreter.

Filename Wildcard Expansion.

Variable Expansion.

Pre Defined Variables.

Command Substitution.

Quotes: Single Quotes and Double Quotes explained.

Backslash - Escape Character.
• Output Streams
Standard Input, Standard Output and Standard Error explained.

Redirection and Pipes.
• Working with Variables
Assigning values to variables

Using the read command

IFS - Internal Field Separator

env, set, export and unset commands.

Using printf to format output.
• Bash Shell Variables
What are Shell Variables?

Special Shell Variables.

Using the shift command.

Using the eval command.
• Declare
Bash Declare statement.

Changing properties of a variable with declare.

Displaying variable properties with declare -p.
• Bash Scripting Basic Structure
Basic Structure of a script.

Using comments.

Handling errors - Custom Error logs.

Execute Permissions using chmod.

$PATH explained.

Adding new paths to $PATH.

Part 2 - Bash Shell Scripting

Functions and Blocks of Code:

• Debugging and Return Codes
Debugging Bash Scripts. Setting return codes.
• Functions
What are functions?

Defining functions.

Working with functions.

Calling functions from within scripts.

Creating a functions library.
• Here Documents
What are Here Documents?

Here document examples.
• Here Strings
What are Here Strings?

Here String examples.

Part 3 - Bash Shell Scripting Basic Structure

Controlling the flow with conditional processing:

• Bash Scripting if statement
Conditional Processing

"if..then..fi"

"if..then..else..fi"

"if ..then..elif..then..else..fi

Testing files and objects with "if" statements.
• Comparing Strings
String Comparison tests.

Using Single Brackets.

Using Double Brackets.

Using Regular Expressions with Double Brackets.
• Bash Scripting Substrings
What are Substrings?

Calculate length of a string.

Extracting a substring from a variable.

Replacing matches within substrings.
• Comparing Numbers
Numerical Operators.

Integer Operators.

Testing numeric values and working with numbers.
• Boolean Operators
Logical Boolean Operators.

Logical Negation, Logical AND, Logical OR.

Combining Logical Operators.
• Bash Scripting Case Statements
Using Case statements to simplify logic within a script.

Pattern matching with case statements.

Mixed case pattern matching using the case statement.

Part 4 - Using Loops within Bash Shell Scripts

Loops:

• Bash Scripting for loop
for loop examples.

Using the for loop within a script.
• Bash Scripting while loop
while loop examples.

Using the while loop within a script.
• Bash Scripting until loop
until loop examples.

Using the until loop within a script.
• Exiting loops
Examples of how to exit a loop.

Using the break command to exit a loop.
• Continue Command
Examples of how to use the continue command within a loop.

Continue to the next iteration within a loop.

Part 5 - Number and Arithmetic

Making calculations in Bash:

• Number and Arithmetic
Mathematical Operations within Bash.

Arithmetic Operators.

Addition, Subtraction, Division and Multiplication.

Using Modulo command - modulo example.

Exponentiation - exponentiation example.

BC - Bash built in arbitrary precision calculator.

Mathematical Functions.

Invoking the Math library.

Part 6 - Arrays

Working with arrays:

• Working with arrays
What is an array?

Array assignment.

Deleting arrays with the unset command.

Bash array example scripts.

Part 7 - Interactive Scripts

Interactive Scripts:

• Getting User Input
Create interactive scripts.

Using the read command.

Simple Menus with echo and read commands.
• Select Statement
Using Select.

Create interactive menus with select statement.

Combining select and case statements to create menus.