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181 lines
9.4 KiB
Markdown
181 lines
9.4 KiB
Markdown
# Linux Basics
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## Introduction
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### Prerequisites
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- Should be comfortable in using any operating systems like Windows, Linux or
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- Expected to have fundamental knowledge of operating systems
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## What to expect from this course
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This course is divided into three parts. In the first part, we cover the
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fundamentals of Linux operating systems. We will talk about Linux architecture,
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Linux distributions and uses of Linux operating systems. We will also talk about the
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difference between GUI and CLI.
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In the second part, we cover some basic commands used in Linux.
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We will focus on commands used for navigating the file system, viewing and manipulating files,
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I/O redirection, etc.
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In the third part, we cover Linux system administration. This includes day-to-day tasks
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performed by Linux admins, like managing users/groups, managing file permissions,
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monitoring system performance, log files etc.
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In the second and third part, we will be showing examples to understand the concepts.
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## What is not covered under this course
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We are not covering advanced Linux commands and Bash scripting in this
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course. We will also not be covering Linux internals.
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## Course Contents
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The following topics has been covered in this course:
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- [Introduction to Linux](https://linkedin.github.io/school-of-sre/level101/linux_basics/intro/)
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- [What are Linux Operating Systems](https://linkedin.github.io/school-of-sre/level101/linux_basics/intro/#what-are-linux-operating-systems)
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- [What are popular Linux distributions](https://linkedin.github.io/school-of-sre/level101/linux_basics/intro/#what-are-popular-linux-distributions)
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- [Uses of Linux Operating Systems](https://linkedin.github.io/school-of-sre/level101/linux_basics/intro/#uses-of-linux-operating-systems)
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- [Linux Architecture](https://linkedin.github.io/school-of-sre/level101/linux_basics/intro/#linux-architecture)
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- [Graphical user interface (GUI) vs Command line interface (CLI)](https://linkedin.github.io/school-of-sre/level101/linux_basics/intro/#graphical-user-interface-gui-vs-command-line-interface-cli)
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- [Command Line Basics](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/)
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- [Lab Environment Setup](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#lab-environment-setup)
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- [What is a Command](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#what-is-a-command)
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- [File System Organization](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#file-system-organization)
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- [Navigating File System](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#commands-for-navigating-the-file-system)
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- [Manipulating Files](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#commands-for-manipulating-files)
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- [Viewing Files](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#commands-for-viewing-files)
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- [Echo Command](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#echo-command)
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- [Text Processing Commands](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#text-processing-commands)
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- [I/O Redirection](https://linkedin.github.io/school-of-sre/level101/linux_basics/command_line_basics/#io-redirection)
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- [Linux system administration](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/)
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- [Lab Environment Setup](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#lab-environment-setup)
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- [User/Groups management](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#usergroup-management)
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- [Becoming a Superuser](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#becoming-a-superuser)
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- [File Permissions](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#file-permissions)
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- [SSH Command](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#ssh-command)
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- [Package Management](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#package-management)
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- [Process Management](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#process-management)
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- [Memory Management](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#memory-management)
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- [Daemons and Systemd](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#daemons)
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- [Logs](https://linkedin.github.io/school-of-sre/level101/linux_basics/linux_server_administration/#logs)
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- [Conclusion](https://linkedin.github.io/school-of-sre/level101/linux_basics/conclusion)
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- [Applications in SRE Role](https://linkedin.github.io/school-of-sre/level101/linux_basics/conclusion/#applications-in-sre-role)
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- [Useful Courses and tutorials](https://linkedin.github.io/school-of-sre/level101/linux_basics/conclusion/#useful-courses-and-tutorials)
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## What are Linux operating systems
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Most of us are familiar with the Windows operating system used in more than
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75% of the personal computers. The Windows operating systems
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are based on Windows NT kernel.
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A _kernel_ is the most important part of
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an operating system—it performs important functions like process
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management, memory management, filesystem management, etc.
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Linux operating systems are based on the Linux kernel. A Linux-based
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operating system will consist of Linux kernel, GUI/CLI, system libraries
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and system utilities. The Linux kernel was independently developed and
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released by Linus Torvalds. The Linux kernel is free and open-source (See
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[https://github.com/torvalds/linux](https://github.com/torvalds/linux)).
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Linux is a kernel and not a complete operating system. Linux kernel is combined with GNU system to make a complete operating system. Therefore, Linux-based operating systems are also called as GNU/Linux systems. GNU is an extensive collection of free softwares like compiler, debugger, C library etc. (See
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[Linux and the GNU System](https://www.gnu.org/gnu/linux-and-gnu.en.html))
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History of Linux -
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[https://en.wikipedia.org/wiki/History_of_Linux](https://en.wikipedia.org/wiki/History_of_Linux)
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## What are popular Linux distributions
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A Linux distribution (_distro_) is an operating system based on
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the Linux kernel and a package management system. A package management
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system consists of tools that help in installing, upgrading,
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configuring and removing softwares on the operating system.
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Software are usually adopted to a distribution and are packaged in a
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distro-specific format. These packages are available through a distro-specific
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repository. Packages are installed and managed in the operating
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system by a package manager.
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**List of popular Linux distributions:**
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- Fedora
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- Ubuntu
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- Debian
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- Centos
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- Red Hat Enterprise Linux
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- Suse
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- Arch Linux
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| Packaging systems | Distributions | Package manager
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| ---------------------- | ------------------------------------------ | -----------------
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| Debian style (`.deb`) | Debian, Ubuntu | APT
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| Red Hat style (`.rpm`) | Fedora, CentOS, Red Hat Enterprise Linux | YUM
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## Linux Architecture
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- The Linux kernel is monolithic in nature.
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- System calls are used to interact with the Linux kernel space.
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- Kernel code can only be executed in the kernel mode. Non-kernel code is executed in the user mode.
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- Device drivers are used to communicate with the hardware devices.
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## Uses of Linux Operating Systems
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Operating system based on Linux kernel are widely used in:
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- Personal computers
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- Servers
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- Mobile phones - Android is based on Linux operating system
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- Embedded devices - watches, televisions, traffic lights, etc.
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- Satellites
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- Network devices - routers, switches, etc.
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## Graphical user interface (GUI) vs Command line interface (CLI)
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A user interacts with a computer with the help of user interfaces. The
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user interface can be either GUI or CLI.
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Graphical user interface allows a user to interact with the computer
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using graphics such as icons and images. When a user clicks on an icon
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to open an application on a computer, he or she is actually using the
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GUI. It's easy to perform tasks using GUI.
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Command line interface allows a user to interact with the computer using
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commands. A user types the command in a terminal and the system helps in
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executing these commands. A new user with experience on GUI may find it
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difficult to interact with CLI as he/she needs to be aware of the commands
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to perform a particular operation.
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## Shell vs Terminal
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Shell is a program that takes commands from the
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users and gives them to the operating system for processing. Shell is an
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example of a CLI (command line interface). Bash is one of the most popular shell
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programs available on Linux servers. Other popular shell programs are
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zsh, ksh and tcsh.
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Terminal is a program that opens a window and lets you interact with the
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shell. Some popular examples of terminals are GNOME-terminal, xterm,
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Konsole, etc.
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Linux users do use the terms shell, terminal, prompt, console, etc.
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interchangeably. In simple terms, these all refer to a way of taking
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commands from the user.
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