Introduction to Linux

Linux is a Unix-like computer operating system assembled under the model of free and open
source software development and distribution. The defining component of Linux is the Linux
kernel, an operating system kernel first released 5 October 1991 by Linus Torvalds.
Linux was originally developed as a free operating system for Intel x86-based personal
computers. It has since been ported to more computer hardware platforms than any other
operating system. It is a leading operating system on servers and other big iron systems such as
mainframe computers and supercomputers more than 90% of today’s 500 fastest supercomputers
run some variant of Linux, including the 10 fastest. Linux also runs on embedded systems
(devices where the operating system is typically built into the firmware and highly tailored to the
system) such as mobile phones, tablet computers, network routers, televisions and video game
consoles; the Android system in wide use on mobile devices is built on the Linux kernel.

1.Linux Utilities:

1.1 File Handling utilities
1.2 Security by file permissions
1.3 Process utilities
1.4 Disk utilities
1.5 Networking commands
1.6 Filters
1.7 Text processing utilities and Backup utilities
1.8 SED
              scripts
              operation
              addresses
              commands
1.9 AWK – execution, fields and record
              scripts, operation
               patterns
               actions
              associative arrays
              string & mathematical functions
              system commands in awk, applications.

Linux/UNIX Shell

Shell programming is an essential aspect of working with Unix-like operating systems, including Linux and macOS. The shell serves as a command-line interpreter, providing users with a text-based interface to interact with the operating system. It allows users to execute commands, manipulate files and directories, automate tasks, and perform a wide range of system-related operations.
The shell acts as a bridge between the user and the underlying operating system. It takes user commands as input, interprets them, and executes the corresponding actions. It provides a powerful and flexible environment for users to control and customize their computing experience.

UNIX Shell programming refers to the process of writing scripts or programs using shell scripting languages such as Bash (Bourne Again SHell), Zsh (Z shell), or other shell variants. These scripting languages provide a set of commands, control structures, and features that allow users to write programs that automate tasks, perform complex operations, and combine multiple commands to achieve desired outcomes.

1. Introduction to Unix Shell Programming
   • What is shell programming?
   • Advantages and importance of shell scripting
   • Different Unix shells (e.g., Bash, Zsh)
   • Setting up a Unix-like environment (Linux, macOS)
2. Getting Started with Shell Basics
   • Accessing the shell (terminal, command prompt)
   • Shell prompt and command syntax
   • Basic commands (ls, cd, mkdir, etc.)
   • Running commands and understanding command output
   • Command-line arguments and options
3. Variables and Data Types
   • Variable declaration and assignment
   • Naming conventions and best practices
   • Working with strings, numbers, and booleans
   • Environment variables and special variables
   • Variable substitution and expansion
4. Control Structures and Flow Control
   • Conditional statements (if, case)
   • Looping constructs (for, while, until)
   • Breaking and continuing loop iterations
   • Branching with the exit command
   • Handling errors and exceptions (error codes)
5. Input and Output Handling
   • Standard input, output, and error streams
   • Redirection of input and output
   • File and directory handling
   • Reading user input
   • Writing to files and appending content
6. Functions and Modularization
   • Defining and calling functions
   • Function parameters and return values
   • Scope and lifetime of variables
   • Code modularization and reusability
   • Creating and using libraries
7. Advanced Topics
   • Regular expressions and pattern matching
   • Command substitution and process substitution
   • Arithmetic operations and mathematical calculations
   • Working with arrays and associative arrays
   • Handling signals and traps
8. Scripting Best Practices
   • Scripting conventions and style guidelines
   • Error handling and logging
   • Input validation and sanitization
   • Debugging techniques (echo, set -x)
   • Security considerations (proper permissions)
9. Real-World Examples and Exercises
   • Writing scripts for common tasks (file manipulation, text processing)
   • Automating system administration tasks
   • Parsing and analyzing log files
   • Building interactive scripts with menus
   • Solving coding challenges and exercises
10. Conclusion and Further Learning
    • Recap of key concepts and techniques
    • Additional resources and references
    • Exploring advanced shell programming topics
    • Practicing and honing shell scripting skills