Bash

Bash is the Bourne Again Shell - a command language and shell used for writing scripts and automating tasks.

What is Bash?

Bash is:

• A command interpreter for interactive use
• A shell for executing scripts
• A programming language for automation
• The default shell on most Linux systems

Why Learn Bash?

• Automation: Automate repetitive tasks
• System Administration: Manage systems efficiently
• DevOps: Essential for infrastructure automation
• Cross-Platform: Works on Linux, macOS, and Windows (WSL)
• Powerful: Access to all command-line tools

Bash Basics

Running Bash Scripts

# Direct execution
bash script.sh

# With shebang and execute permission
#!/bin/bash
./script.sh # (after chmod +x)

# Source/execute in current shell
source script.sh
. script.sh

Script Structure

#!/bin/bash

# Comments start with #
# This is a comment

# Variables
VARIABLE_NAME="value"

# Commands
echo "Hello, World!"

# Functions
my_function() {
    echo "This is a function"
}

# Call function
my_function

Topics Covered

1. Variables - Storing and using data
2. Conditions - Making decisions with if/else
3. Loops - Repeating actions with for/while
4. Functions - Creating reusable code blocks

Common Use Cases

• Deployment scripts
• System monitoring
• Backup automation
• Log processing
• Configuration management
• CI/CD pipeline scripts
• Infrastructure provisioning

Best Practices

• Always include shebang (#!/bin/bash)
• Use meaningful variable names
• Quote variables: "$var"
• Use functions to organize code
• Add error checking
• Include comments
• Test thoroughly
• Make scripts portable

Let's start learning Bash!