Fundamentals of Linux

• Linux is an Open Source Operating System

• OS is an interface between User Applications and Underlying Hardware

• Linux OS was created based on Unix

Linux Distributions, also known as Flavors of Linux

• Centos / RHEL

• Debian / Ubuntu

• Fedora

• Amazon Linux

  • Based on Fedoro Distribution

What is Kernel

• Core of Linux OS is called as Kernel

  • Creates a dedicated Address Space to run any application/task/process

    • Storage

    • Network

    • IPC - Inter-Process Communication

    • Security

    • User Management

    • Namespaces

    • Control Groups

    • Process

      • Will be assigned with unique process Id.

Package Manager

• Used to Manage the packages

• Install/Un-install/Update the Packages

Package managers used for different Linux distributions

• Centos / RHEL : yum

• Debian / Ubuntu : apt-get / apt

• Fedora : dnf

• Amazon Linux : dnf(latest Amazon Linux) / yum(previous version)

• Package Managers are executed as a root user.

  • Once we login to Linux Machine

  • Elevate the Access to root user level.

    • sudo -i # To Elevate the access to root user.

DevOps Team Roles & Responsibilities

• Install all the DevOps Tools/Packages and Services on Linux Machines.

• Package Management :

  • Periodic Upgrade of packages

    • Upgrade - update and clean-up the previous version

    • Update - Just Update to New Version

  • Un-install the Packages

  • Back-up and Restore

• Remote Server Management - i.e., Client Server Architecture

• Manage Linux Machines :

  • Package Management

  • File Management

  • User Management

  • Access Management

  • Remote Server Management

    • SSH (Secure SHell) Protocol

      • SSH Connection using Port 22.

        • Host Name

        • User Name

        • Credential

          • Types of Authentication :

            • Password based Authentication

            • Token based Authentication

            • Key based Authentication

              • Private key

              • Authorized_keys / Public Key

            • Passwordless Authentication

  • Process Automation

    • Linux Shell Scripting