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-marp: true
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-title: An introduction to Linux
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-author: P.Y. Barriat
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-description: https://dev.to/nikolab/complete-list-of-github-markdown-emoji-markup-5aia
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-backgroundImage: url('assets/back.png')
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-_backgroundImage: url('assets/garde.png')
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-footer: 13/04/2023 | An introduction to Linux | PY Barriat
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-_footer: ""
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-paginate: true
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-_paginate: false
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----
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-
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-An introduction to Linux<!--fit-->
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-===
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-https://gogs.elic.ucl.ac.be/pbarriat/learning-linux
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-
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-**Pierre-Yves Barriat**
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-ACELI Training Sessions `April 13th, 2023`
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----
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-
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-# What is UNIX ?
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-
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-- Operating System
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- > Windows 10 (Microsoft), MacOSX (Apple), Android (Google), etc
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-- UNIX is a (family of) Operating System
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-- Invented by AT&T Bell Labs in late 60's
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-- Currently there are different versions and variants of UNIX
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- > Solaris, AIX, HP-UX, etc.
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-- UNIX is **not** free or Open Source: "GNU is Not UNIX"
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----
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-
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-# What is Linux ?
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-
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-- GNU (80's) is a free, open source version of the UNIX OS, but without the most important element: the **kernel**
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-- Linux kernel was developed in 1991 by Linus Torvalds, a Finnish graduate student
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-- The association GNU/Linux is an operating system (say just "Linux") and provides an alternative to commercial operating systems
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-- Linux exists without GNU (eg Android) : used to power a multitude of systems... from your phone to your smart fridge
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----
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-
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-# What is a Linux distribution ?
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-
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-- Many versions of Linux
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- > Red Hat, Debian, Suse, etc
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-
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-- But one common linux kernel: **kernel** is like an **engine**. A distribution is an actual car that hosts the engine
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-- Distributions differ from
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- - the application/management layer
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- - GUI (Graphical User Interface = desktop environment)
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- - software packages
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- - help-desk, support, language
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----
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-
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-# Why Linux ?
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-
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-- **Linux is free**
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-- Linux is supported on older computers (perf & updates)
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-- Linux has many more free applications
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-
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-`Security`: there are very few viruses for Linux
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-`Privacy`: most Linux distributions don't collect your data at all
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-`Reliability`: if you want to stop something, you really can
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-`Updates`: package manager
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-`Customisation`: you can make Linux look, feel and behave as you want it to
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-`Command Line Interface:` faster & efficient
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----
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----
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-
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-# Linux Statistics
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-- 47% of professional **developers** use Linux-based operating systems (Statista)
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-- Linux powers 39.2% of **websites** whose operating system is known (W3Techs)
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-- Linux powers 85% of **smartphones** (Hayden James)
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-
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-<!-- _footer: "https://truelist.co/blog/linux-statistics/" -->
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----
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-<!-- _footer: "https://truelist.co/blog/linux-statistics/" -->
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----
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-
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-# Why not Linux ?
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-
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-1. Hardware compatibility (printers, etc)
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-2. Missing famous software (MS Office, Adobe, CAO, etc)
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-3. Gaming
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-
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-### Workarounds
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-
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-1. Many devices "Linux compatible"
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-2. Emulation (eg virtualbox), online usage, alternatives (GIMP)
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-3. Difficult, but it exists emulation and Steam
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-
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----
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-
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-# Distribution: why Ubuntu ?
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-
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-- easy to install and easy to use
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-- easy to maintain and update
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-- useful applications
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-- looks nice
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-- wide variety of supported applications
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-- strong community support
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-- better driver support
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-- LTS and staging releases available as per user needs
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-
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-> get the latest Ubuntu LTS : [ubuntu-22.04.2-desktop-amd64.iso](https://releases.ubuntu.com/jammy/ubuntu-22.04.2-desktop-amd64.iso)
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-
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----
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-
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-# Test Linux inside Windows: how ?
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-
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-Using a virtual machine: test Linux without changing anything to your computer
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-
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-You need to install a VM and then install the Linux inside
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-- Get a Virtual Machine: https://www.virtualbox.org/wiki/Downloads
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- > VirtualBox + Extension Pack
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-
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-- Install Linux in a VM: [Install Linux Inside Windows Using VirtualBox](https://itsfoss.com/install-linux-in-virtualbox/)
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- > Step by Step Guide
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----
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-
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-# Linux GUI
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-A Linux distribution contains a [display server](https://www.google.com/search?tbm=isch&q=display+manager), a [window manager](https://www.google.com/search?tbm=isch&q=windows+manager) (manage windows, panel, menus, dash interfaces and core applications), and a [desktop environment](https://www.google.com/search?tbm=isch&q=graphical+interface) (eg status bars, drag-and-drop capabilities, etc)
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-These 3 items are **bundled together** to make what is known as a `GUI environment`
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----
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-
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-# Using Linux
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-**Using Linux through a GUI environment is similar to Windows or MacOSX**
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-Linux users do not install software the same way that Windows users do: Linux has a tool known as a `package manager`
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-
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-A package manager provides a way to search for software, install software, keep the software up to date and remove the software
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-> Similar to Google or Apple store
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-
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----
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-
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-# Linux CLUI
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-
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-Using Linux with GUI, it's already great !
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-**Using CLUI = unlock the power of Linux !**
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-
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-Each Linux system contains a terminal
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-A terminal is where you enter Linux commands
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-
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-It's called the **C**ommand **L**ine **U**ser **I**nterface
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-
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-CLUI is one of the many strengths of Linux and can be more efficient than using the GUI
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-
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----
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-
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-# Linux CLUI
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-
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-- CLUI allows users to be independent of distros (or UNIX systems like OSX)
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-- CLUI saves system resources which are consumed by GUIs
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-- CLUI allows users to easily work at distance (SSH)
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-- CLUI allows developers to join together simple (and less simple) commands to do complex things and automate... whatever you want to
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-
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-> People tend to think command line is difficult. It's not.
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-
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----
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-
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-# Linux Shell
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-
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-A **shell** is a program that takes commands from the keyboard and gives them to the operating system to perform
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-
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-The main function is to interpret your commands **= language**
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-
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-The **bash** shell is one of several shells available for Linux
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-
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-Learning the shell:
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-
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-> *"When you are a child you use a computer by looking at the pictures. When you grow up, you learn to read and write"*
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-
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-It's more or less like SMSing to your PC, telling it what to do
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-
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----
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-
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-# Linux Shell
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-
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-Shells have some built-in commands
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-
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-A shell also supports programming constructs, allowing complex commands to be built from smaller parts **= scripts**
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-
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-Scripts can be saved as files to become new commands
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-> many commands on a typical Linux system are scripts
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-
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-An open terminal show you a **PROMPT** waiting for your commands
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-Commands can have **options** and parameters
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-
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-All your commands are saved in a **history**
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----
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-
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-# Linux Shell Demo
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-
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-Rename many files at once ?
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-
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-```bash
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-mmv '*.JPG' '#1.jpg'
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-```
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-
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-Download a youtube video ?
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-
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-```bash
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-youtube-dl https://www.youtube.com/watch?v=G7KNmW9a75Y&ab_channel=MileyCyrusVEVO
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-```
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-
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-Convert color pictures in BW at once ?
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-
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-```bash
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-#!/bin/bash
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-for file in *.jpg
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-do
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- convert ${file} -colorspace Gray "${file%.*}_bw.jpg"
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- echo "${file}... converted"
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-done
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-```
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-
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----
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-
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-# Online Linux Demo
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-
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-- [Run Linux or other Operating Systems in your browser](https://bellard.org/jslinux/)
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-- [Run bash (and others) scripts online ](https://rextester.com/l/bash_online_compiler)
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-- [Free online containers and virtual machines that run full Linux systems](https://linuxcontainers.org/)
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-- [Free GNU/Linux Online Terminal learning platform ](https://www.webminal.org/)
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-
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-- [CISM/ELIC Jupyter portal](https://jupyter.cism.ucl.ac.be)
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- > you need a UCLouvain/CISM account: see [here](https://www.cism.ucl.ac.be/doc/_contents/About/cilog.html)
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-
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----
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-
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-# What you'll learn
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-
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-- Navigating the File System
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- > Get up and running with the CLUI by navigating directories and files
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-- Viewing and Changing Files and Directories
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- > Learn to manipulate directories and files from the CLUI
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-- Configuring the Environment
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- > Learn to configure the environment using the CLUI
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-- Accessing Linux remotely
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- > Learn to use SSH (basics)
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-
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----
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-
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-# Navigating the File System
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-
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-A file system is a section of hard disk that has been allocated to contain files
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-> it's arranged like hierarchical tree structure
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-Files are grouped in the directory structure
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-The top of the tree is called `root` and `/` is used to present the `root`
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----
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-
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-### Absolute paths
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-
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-In the tree `/users/usern/file1` is an absolute pathname
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-
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-### Relative paths
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-If you are already in the `users` directory, the relative pathname for `file1` is `usern/file1`
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-- `~` (tilda) points to the user's **home directory**. Useful if you are logging into a workstation with many users. It's the **default working directory** when you log in. If you are user `usern`, then `/users/usern/file1` is the same as `~/file1`
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-- `.` refers to the current directory
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-- `..` refers to the parent directory
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-
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----
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-
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-# Basic commands
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-
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-- `ls` : lists folders/files in a directory
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-- `cd` : change directory
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- > use `cd name` to navigate to directory name
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-- `pwd` : print working directory. Prints the path of the current directory
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-- `du` : disk usage. Shows the disk usage of the current directory
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-- `man` : manual
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- > use `man name` to bring up a manual entry for command or program called `name`
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-
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----
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-
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-### Creation
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-- `mkdir` : use `mkdir name` to create a new directory named `name` in the current directory
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-- `cp` : use ```cp file1 file2``` to create `file2` which is a copy of `file1`
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- > can also use `cp -r` to copy whole directories
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-- `mv` : move = same as copy, but deletes the original file
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-
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-### Deletion
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-- `rm` : delete files ( cannot recover your files after removed them ! )
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- > can also use `rm -rf` to remove whole directories
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-
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-**Be careful : there is no trash in CLUI**
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-
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----
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-
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-- `tab` is used for auto-complete 
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- > If a file/directory name was partly typed in, **tab will auto-complete** it
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- > If there are multiple options, tab will auto-complete up to the point where the options branch and show you a list of possible options
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-
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-- `*` is used as a wild card
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- > `rm blah*` removes all files which start with `blah`: eg `blah1`, `blah2`, and `blahblah` would all be removed
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-
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- > using `cp public/* private/` copies all files in a `public` directory into a `private` directory, and keeps all file names intact
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-
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----
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-
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-# File permissions
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-
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-### Groups
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-
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-Each file and directory has three user based permission groups
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-
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-- **owner** :the `owner` permissions apply only the owner of the file or directory, they will not impact the actions of other users
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-- **group** : the `group` permissions apply only to the group that has been assigned to the file or directory, they will not effect the actions of other users
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-- **all users** : the `all users` permissions apply to all other users on the system, this is the permission group that you want to watch the most
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-
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----
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-
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-### Types
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-
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-Each file or directory has three basic permission types
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-
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-- **read** : the `read` permission refers to a user's capability to read the contents of the file
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-- **write** : the `write` permission refer to a user's capability to write or modify a file or directory
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-- **execute** : the `execute` permission affects a user's capability to execute a file or view the contents of a directory
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-
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----
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-
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-The following command :
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-
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-```bash
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-ls -l
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-```
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-gives :
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-
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-| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
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-| --------------- | --------------- | ------------ | ------- |----------- | ------- | ---------- |
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-| `-rwxr-xr-x` | `1` | `dupont` | `grpelic` | `3528` | `2022-08-04` | `file_1` |
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-| `drwxr-xr-x` | `3` | `dupont` | `grpelic` | `512` | `2022-01-02` | `dir_1` |
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-| `lrwxr-xr-x` | `2` | `dupont` | `grpelic` | `210` | `2020-12-16` | `short -> /data` |
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-| `-rw-------` | `1` | `dupont` | `grpelic` | `4587` | `2022-12-04` | `file_2` |
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-
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----
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-
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-# Linux privileges
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-
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-
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-
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-Linux has a robust permissions system: this is a very good thing, as it enables a **clear separation** of roles among users
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-
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-Especially between the `root` user and your `standard` user
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-
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-Sometimes, though, you might want your standard user to have **some** or **all** of root's privileges : this is accomplished with `sudo`
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-
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----
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-
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-# Shell syntax rules
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-
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-Shells use three **"standard I/O streams"**
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-
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-- `stdin` is the standard input stream, which provides input to commands.
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-- `stdout` is the standard output stream, which displays output from commands.
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-- `stderr` is the standard error stream, which displays error output from commands.
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-
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-Shell has several **meta-characters** and **control operators**
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-
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-> `|`, `&`, `>`, `;` , etc.
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-
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----
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-
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-# Environment
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-
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-In a bash shell many things constitute your environment
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-
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-- the form of your prompt
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-- your home directory and your working directory
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-- the name of your shell
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-- functions that you have defined
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-- etc.
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-
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-Environment includes many variables that may have been set **by bash** or **by you**
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-> Access the value of a variable by prefixing its name with `$`
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-
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----
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-
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-# Environment variables
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-
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|
-- `USER` : the name of the logged-in user
|
|
|
-- `UID` : the numeric user id of the logged-in user
|
|
|
-- `HOME` : the user's home directory (similar to `~` )
|
|
|
-- `PWD` : the current working directory
|
|
|
-- `SHELL` : the name of the shell
|
|
|
-
|
|
|
-Set a shell variable : typing a name followed immediately by an equal sign ( `=` )
|
|
|
-> if the variable exists, you will modify it to assign the new value
|
|
|
-
|
|
|
-You can use special files to control bash variables : `$HOME/.bashrc`
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-# Remote Linux Access
|
|
|
-
|
|
|
-`SSH` (or **S**ecure **SH**ell) is a **protocol** used to securely log onto remote systems
|
|
|
-> the most common way to access remote Linux and Unix-like servers
|
|
|
-
|
|
|
-`VNC` (or **V**irtual **N**etwork **C**omputing) is a **software** that allows a personal computer's desktop environment to be run
|
|
|
-
|
|
|
-Aside from bandwidth, latency and security issues (which can vary a bit), the big differences are the functionality
|
|
|
-- VNC exports a whole session, desktop and all (GUI)
|
|
|
-- SSH runs a single program (CLUI) and show its windows on your machine
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-# Remote Linux using SSH
|
|
|
-
|
|
|
-You need:
|
|
|
-- an access to the distant machine : login/password
|
|
|
- > or a login with SSH keys (with passphrase)
|
|
|
-- the hostname or the IP address of the distant machine
|
|
|
-- and (of course) a UNIX terminal
|
|
|
-
|
|
|
-```bash
|
|
|
-ssh -X pbarriat@coriolis.elic.ucl.ac.be
|
|
|
-
|
|
|
-ssh -X -i ~/.ssh/id_rsa.ceci pbarriat@gwcism.cism.ucl.ac.be
|
|
|
-```
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-# Remote Linux from Windows
|
|
|
-
|
|
|
-Using a SSH client to reach a distant Linux Workstation
|
|
|
-
|
|
|
-**mobaXTerm** is free and easy to use
|
|
|
-> allow you to test a Linux environmment but in CLUI only
|
|
|
-
|
|
|
-Get a SSH client
|
|
|
-https://mobaxterm.mobatek.net/download-home-edition.html
|
|
|
-
|
|
|
-How to use a SSH client
|
|
|
-https://support.ceci-hpc.be/doc/_contents/QuickStart/ConnectingToTheClusters/MobaXTerm.html
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-# Linux text editors
|
|
|
-
|
|
|
-### GUI
|
|
|
-
|
|
|
-- nedit (simple text editor available in most distributions)
|
|
|
-- Kate, Gedit (KDE, Gnome)
|
|
|
-
|
|
|
-### CLUI
|
|
|
-
|
|
|
-- vi (available in all Unix systems) and **vim** (vi improved)
|
|
|
- > Difficult to learn for beginners used to graphical text editors
|
|
|
- > Very productive for power users
|
|
|
- > [Vim Cheatsheet](assets/vim-cheatsheet.pdf)
|
|
|
-- nano (friendly and easier to learn)
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-# Scripting
|
|
|
-
|
|
|
-How to do a backup ?
|
|
|
-- with Dropbox or Google Drive ?
|
|
|
-- with a private cloud such as Nextcloud ?
|
|
|
-- with an other drive and/or an external drive ?
|
|
|
-
|
|
|
-Backup on external drive ?
|
|
|
-- manually ?
|
|
|
-- with Windows tools ?
|
|
|
-- with external softwares ?
|
|
|
-
|
|
|
-**Why don't do that with a simple linux script ?**
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-# Conclusions
|
|
|
-
|
|
|
-| Advantages of Linux | Disadvantages of Linux |
|
|
|
-| --------------------- | ---------------------------------- |
|
|
|
-| Cost | Not easy to master ( **CLUI only** ) |
|
|
|
-| Security and robustness | Hardware compatibility issues ( sometimes ) |
|
|
|
-| Freedom | Not compatible with some Windows software |
|
|
|
-| Software ||
|
|
|
-| Development ||
|
|
|
-
|
|
|
----
|
|
|
-
|
|
|
-### Need to know more about available Linux applications ?
|
|
|
-
|
|
|
-[Check out the list of the best Linux software](https://www.makeuseof.com/tag/best-linux-software/)
|
|
|
-
|
|
|
-### Need help with bash scripting ?
|
|
|
-
|
|
|
-- [Bash Scripting Tutorial for Beginners](https://linuxconfig.org/bash-scripting-tutorial-for-beginners)
|
|
|
-- [My favorite CLUI cheatsheet](assets/Linux_CLI_Cheat_Sheet.pdf)
|
|
|
-- [Bash scripting cheatsheet](https://devhints.io/bash)
|
|
|
-
|
|
|
-### Need help with Ubuntu ?
|
|
|
-
|
|
|
-The massive community is one of Ubuntu's biggest strengths
|
|
|
-> Visit https://askubuntu.com/ or https://answers.launchpad.net/
|
