Day 1 Introduction to Linux

Agenda for Day 1

• Linux Overview
• Linux History
• Linux Installation
• RHEL 8 Installation on VMware Workstation
• Ubuntu 20 Installation on VMware Workstation
• SUSE 15 Installation on VMware Workstation
• Rocky Linux Deployment on VMware vCenter
• Ubuntu Deployment on Azure
• Ubuntu Deployment on AWS
• CentOS Deployment on GCP
• Connecting to Linux Server using PuTTY
• Boot Process of Linux

Introduction to Linux

Linux is an open-source operating system that manages hardware resources like CPU, memory, and storage while allowing applications to run efficiently.

Core Components

• Kernel – Manages system resources and hardware communication
• System User Space – Shell, background services, utilities
• Applications – Software for user and business tasks

Linux is known for:

✔ Open Source

✔ Stability

✔ Security

✔ Scalability

✔ Cost Effectiveness

History of Linux

Linux was created in 1991 by: Linus Torvalds

What began as a personal project became the backbone of modern IT infrastructure worldwide.

Importance of Linux in the IT Industry

Linux powers:

• Enterprise Servers
• Cloud Platforms
• Android Devices
• Embedded Systems
• Web Infrastructure

Major cloud providers relying heavily on Linux:

• Amazon Web Services
• Microsoft Azure
• Google Cloud

Popular Linux Distributions Covered

• Red Hat Enterprise Linux – Enterprise-grade support
• Ubuntu – Beginner-friendly & cloud-ready
• Rocky Linux – Community-driven RHEL alternative
• SUSE Linux Enterprise – Enterprise & SAP optimized

Installing Linux on Virtual Machines

Virtualization tools used:

• VMware Workstation
• VMware vCenter

Installation Flow:

• Download ISO image
• Create VM
• Allocate CPU, RAM, Disk
• Boot from ISO
• Complete installation

Installation of RHEL8 with GUI on VMware Workstation:

Installation of Ubuntu VM on VMware Workstation 

Deploying Linux on VCenter

Steps:

• Log in to VCenter.
• Create a new virtual machine.
• Select Linux as the guest operating system.
• Upload the Linux ISO image.
• Follow the installation process.

Advantages:

• Centralized management of VMs.
• High availability and scalability.

Migrating VM from One ESXi Host to Another

• Power Off the VM: Shut down the Rocky Linux virtual machine to avoid data corruption during migration.
• Initiate Migration: In VCenter, right-click on the VM and select "Migrate".
• Choose Migration Type: Select "Change Host" to move the VM to another ESXi host.
• Select Destination Host: Pick the target ESXi host from the list of available hosts.
• Validate Resources: Ensure the destination host has sufficient CPU, memory, and storage for the VM.
• Complete Migration: Confirm the migration process and monitor its progress until completion.
• Power On the VM: Start the Rocky Linux VM on the new ESXi host to verify functionality.

Deploying Linux on Cloud

Azure Deployment

• Create VM
• Select Linux image
• Configure networking
• Access via SSH

AWS Deployment

• Launch EC2
• Select Linux AMI
• Configure instance
• Connect via SSH

GCP Deployment

• Create Compute Engine
• Choose Linux image
• Configure machine type
• Access via SSH

Connecting to Linux Using PuTTY

We used:  PuTTY

• Steps covered:
• Enter IP address
• Select SSH (Port 22)
• Configure key authentication
• Connect securely

Linux Boot Process

Understanding boot flow is critical for system troubleshooting.

Boot Stages:

1. BIOS/UEFI Initialization

• The system firmware (BIOS/UEFI) initializes hardware components and performs the POST (Power-On Self-Test).
• It locates and loads the bootloader from the configured boot device.

2. Bootloader (GRUB2)

• GRUB2 (Grand Unified Bootloader) is loaded into memory.
• Displays the boot menu and allows the user to select the kernel or recovery options.
• Loads the selected Linux kernel into memory and passes control to it.

3. Kernel Initialization

• The Linux kernel is loaded and initialized.
• It detects and initializes hardware, mounts the root filesystem, and starts the init process.

4. Init System (Systemd)

• Systemd, the default init system, takes over.
• Reads the configuration files and starts essential services.
• Initializes the target runlevel or default system state.

5. User Space

• The system transitions to user space.
• Services like networking, logging, and graphical interfaces are started.
• The login prompt or graphical desktop environment is presented to the user.

Understanding Boot Target in Linux 

In Linux, a boot target refers to a predefined system state or mode that the system is configured to reach after booting.

Modern Linux systems use systemd targets instead of traditional runlevels.

Common Boot Targets

• graphical.target:  Boots into a graphical user interface (GUI).
• multi-user.target : Boots into multi-user, non-graphical mode (similar to runlevel 3).
• rescue.targetc: Single-user mode with minimal services for recovery.
• emergency.target : Minimal environment with only root filesystem mounted.
• poweroff.target : Shuts down the system.
• reboot.target : Reboots the system.

Commands Used:

• systemctl get-default
• systemctl list-units --type=target
• systemctl set-default multi-user.target
• systemctl set-default graphical.target

🎓 Day 1 Outcome

By the end of Day 1, participants:

✅ Understood Linux fundamentals

✅ Installed Linux on VMware

✅ Deployed Linux on cloud platforms

✅ Learned secure SSH connectivity

✅ Understood Linux boot architecture

✅ Learned systemd boot targets