Deconstructed Learning System

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A Very Simple Linux Guide And Reference

Demystifying Linux

This is a repository dedicated to all things Linux and aims to act as a reference for popular and useful commands as well as crucial Linux concepts from A - Z. The material in this repo is delivered in a way that is friendly for the Linux confused, unaware, beginners - advanced users. If you read through the bulk of this repository you will know Linux.

Deconstructed Learning System

Learning in steps based on the basics Notice: How to install Linux is further down in steps. This is by design.

  1. What is Linux ?
  2. Learning The Linux file structure
  3. How do you navigate around a Linux system
  4. What is a command ?
  5. How do people install programs in Linux ?
  6. How do you update Linux and programs installed in it ?
  7. What are some differences between Linux, Windows and MacOS ?
  8. Why do people use Linux ?

The Index

(click on the thing to jump to the thing)

Who is this repository for ?

*There are many explanations in this repository to either introduce you to concepts or clarify them in a calm simple way.

Assumptions

These are things this repository assumes or assumes you could just google really quick.

Terminology Definitions

What this repositories goal is

There is a huge barrier to getting started using Linux or just finding out what the the heck it is and what its used for.

Examples of barriers to entry

This repo can help clarify some of the following questions and concerns as well as the above barriers to entry.

Where to start

In other words just start here by reading on. I keep things as simple as possible while still getting into a descent amount of detail.

Here is my recommended structure of how you should learn Linux:

Start with the steps in my Deconstructed Learning System <– (click) Once you make it through the basics move on to things below that you have not learned about yet or just learn the below right from the jump if you don’t like to approach things in steps.

(Keep in mind all of these things are answered here and you could just click on the thing to jump to a breakdown of it.)

Learn :

In a shell by using commands:
  • What a command flag is and how to use them.
  • What a man page is and how to access one and effectively read them.
  • How to change directories, create a file and directory, remove a file or directory.
  • How to view the contents of a file.
  • How to edit the contents of a file.
  • How to rename a file or folder.
  • How to know which working directory you are in and what is a working directory ?
  • How to move a file or folder to a different place.
  • How to copy, cut and paste a file or folder.
  • How to view the history of all the commands you have ever used.
  • How to update your system.
  • How to set your default applications.
  • How to create, give a password and home directory to a new system user.
  • How to change file and folder permissions.
  • How to make something executable.
  • The export command.

What is Linux ?

Linux is an open source operating system based on an older proprietary operating system called Unix.

Some dood came along one day and thought wait.. this Unix OS thing should be free, im gonna work on that! And thus Linux was born. The doods name is Linus so he combined his name with Unix and presto we got Linux.

Operating system:

Open source:

Why do people use Linux ?

There is not one answer to rule them all but here are five reasons along with a couple of examples.

1. Free and open source stuff

Linux is free and most applications or pieces of software that run on Linux are open source and free as well. Linux provides simple ways to find a similar, many times better, open source version of popular paid software using some kind of package management tool or git. The vast majority of the time these open source programs can read and output files in popular formats such as .psd, .docx, .xls, .ppt etc.. What this means is that you are not limited to being confined by a paid program like photoshop simply because it outputs files in .psd format and your coworkers need that file format for a specific project. Open source also means that people are constantly going to be working on this thing and making it better.

A few examples:

2. Programming / Developing

You can be a developer and use just about any modern operating system. Linux just makes it a little bit easier for specific languages like C, verilog, java, python, javascript, nodejs and many others. What I mean is that out the box many flavors of Linux either already come with enviornments set up to get started programming quick or have the ability to set up the enviornments quickly and seemlessly.

3. Security

Linux enviornments are really easy to make secure and out the box are much more secure than a windows enviornments. Linux systems out the box are also a lot more secure from a user accidentally messing something up or damaging crucial system files.

4. Hosting Services

You want to have the following for free:

You can do all of that and so much more in a Linux system with a little bit of reading, a little bit of patience, a little bit of elbow grease and a little bit of trial and error.

5. Customization

You dont like the way something looks or the way someting is behaving. You can easily change it in Linux. The entire graphical user interface or command line interface can be completely customized to how you want it to look. You can make simple changes or crazy drastic changes you never knew were possible.

One personal reason for using Linux framed the way I think. (Keep in mind im a python developer)

  • I have a bunch of older laptops that I dont want to throw away and I want to continue to get use out of.
  • If I install windows on them they become unusable because everything takes a very very long time to run.
So what are my options ?
Linux is lightweight
  • Meaning it doesnt take up a whole bunch of space on a hard drive if you install it. Even a hard drive thats only 20 gb large could work for a Linux install.
  • Linux manages a computers working memory really well so it doesnt stay stuck loading something for a long time.
  • The applications that run on Linux are also small in size so you can install many of them without needing a big hard drive.
  • Linux applications are not resource heavy so Linux has an easier time running them.
Alright so I install Linux and now all these machines are usable and some how magically run really fast.
  • Cool so now I have all of these revitalized machines.
What am I going to do with them ? I have three. They are all laptops.
Well.. I have always wanted my own website.
  • I dont want to pay for a website and I dont want to host my files on some server somewhere that is just running Linux anyways.
  • Ill use one of the three machines, the most powerful one, as a webserver, cloud server and media server.
  • The second most powerful machine I will use to code on. Im a python developer so that will be useful.
Ok from all of this coding sitting down for too long hurts my back so ill create some kind of a way where I could either sit or stand at my desk.
  • Sitting and standing is cool but sometimes I wish I could lay down and get work done also.
  • If I could switch between the three work modes, sitting, standing and laying, I bet I could be ultra productive.

    Idea !

  • Ill use the third remaining machine to set up some kind of bed programming situation where I have the machine rigged in such a way that I could code while laying down in my bed.
  • I will also make sure that this laptop is easily detachable so I could use it as my mobile work station also.
Cool all that worked ! Now im ultra productive.
Its getting a little annoying sending files that im working on back and forth from each machine.

Ah I know ! Ill use my main server also as a git server hosting all of my work files securely.

  • When I make changes to something its all managed and sent to one place.
  • Git is cool too because if I mess something up I can just roll back the changes to a previous time.
  • If I want I could also invite others to work on a project and just create a seperate user accounts for them on my server.

The Linux file structure

bin: Binaries Folder

sbin: System Binaries Folder

Both of these folders contain the files that need to be accessible in single user mode as opposed to multi-user mode.

Single user mode

  • A special mode which boots you in as a root user to do system repairs, upgrades or testing.
  • Programs are not typically installed in these directories unless they are system programs.

boot: Boot Folder

dev: Devices Folder

etc: Etc.. Folder

lib\lib32\lib64: Library Folders

media: Media Folder

mnt: Mount Folder

opt: Optional Folder

proc: Process Folder

root: Root Folder

run: Run Folder

srv: Service Folder

sys: System Folder

tmp: Temporary Folder

usr: User Application Space

var: Variable Folder

home: Home Folder

THE INITRAMFS{What is it?}:

An initramfs is a filesystem that is embedded into the kernel and loaded at boot time. It is used to mount the real root filesystem and to provide early userspace with the necessary drivers and tools to boot the system. The initramfs is usually generated by the kernel build system and contains all the necessary files and drivers to boot the system. However, it can also be generated by the user and loaded into the kernel manually. Initramfs is an important part of the Linux boot process and is essential for systems that require special boot configurations or that need to load additional drivers or modules at boot time.

What is a shell ?

A shell is a Linux command line interpreter. What the hell does that mean ? It means that Linux has a bunch of specific words called commands that are used to make the operating system do stuff and a shell is a program that understands those words or commands and can make use of them. Shells also have built in programming languages which let you write “scripts” you can run to do more stuff or automate things.

What is a terminal ?

A terminal is an application or piece of software that allows a user to interact with a shell. There are a lot of different kinds of terminals that either specialize in a specific thing or allow you to customize the way you interact with a shell. You could do all of the regular stuff your used to doing on a computer inside of a terminal. Terminals along with command line shells are an explicit way of interacting with your computers operating system. Clicking around using your mouse or trackpad is an implicit way of interacting with your computers operating system. When you click around and create a file or edit a file or open a program your computer is actually running all these commands in the background. This means if you wanted to you could just type the commands into a terminal directly.

How do you find or access a terminal in Linux ?

One of these will do it.

Which terminal should you use ?

It doesn’t really matter. Once you get more into Linux you play with different terminals and start to like certain ones for specific reasons such as:

Honestly, its not too tricky to customize any terminal. Any will do.

What is a man page ?

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What is a command ?

A command is a word/term that is a reference to an application, a serrvice, a protocol, a feature installed or accessible in your operating system which invokes/creates some kind of action.

Please see the following related material

Where do you type commands ?

[ ] You type commands in a terminal. [ ] A terminal will give you access to a shell which will be the thing that knows how to understand the commands you type in the terminal.

What is a command flag ?

A command flag is a thing you type after a command that makes the command behave differently. We are going to use the ls command as an example.

The ls command: ls is short for the word “list”. The ls command shows you a list of files and folders in whatever working directory you are in.

If I type the command “ls” in a terminal like this and then press enter.

> ls

This is the output of that command.

</img>

You see! In the terminal I now have a list of files and folders relative to the directory im in, which in this case is my home directory.

Alright cool. Now lets try using a command flag with the ls command.

> ls -a

</img>

You see! For the ls command the -a tells the command to list all files and folders even the hidden ones. This is an example of a command flag and it changing the behavior of a command.

Commands usually have a ton of different command flags.

Ok so how do you find command flags for a specific command though ? You could usually type the command name in a terminal followed by a space and either –help or -h, alternatively you could also type “man ls” or “man ‘Command_name_here’” without ANY of the quotes. Unfortunately documentation is really annoying for a beginner and you dont learn till later that you werent suppose to type the command with the brackets or the quotes or something else. There is also a lack of real world examples in documentation and they just kind of assume that you could figure it out. You could always ask google something like “ real examples of the ls command “. I also am doing the best I can to de-mystify things in the realm of this idea here in this repo so hopefully you could just find your answer here.

What is a Linux distribution ?

It’s just a unique version/flavor of Linux that people made. Like ice cream anyone can source the ingredients of Linux and make their own flavor. Most distributions of Linux are not too different from each other and if you learn how to navigate around one you can without too much difficulty figure out another.

Here is a small list of what different distributions might be tailored towards:

Here is a small list of some actual distributions:

Some distributions of Linux are built off of other distributions.

Ex. Ubuntu is built off of Debian Manjaro is built off of Arch Fedora is built off of RedHat

Here are a few examples of what certain distributions are geared towards and why.

Which distribution should you choose ?

Answer these questions first.

My Linux Journey for context I started using Linux in 1997 for no good reason other then I was and am still obsessed with computers. The first distribution I used was called Slackware which is currently the oldest distribution still maintained. It was very hard for me. I had to read a ridiculous amount just to do simple things that I could do on windows willy nilly. The community was not nice. I would go on to forums and ask questions and everyone would say the same thing RTFM! Which means Read The F’ing Manual. The pros are I did end up reading the f’ing manual and as a result I learned a lot. The cons are I wasted so much time going down the wrong path on many occasions but when your 14 you have time.

So look. If your new most people recommend Ubuntu or a Debian based distro. Im a Arch guy now, well Manjaro to be more specific. Im a programmer and I have old computers I want to still use for stuff. With Manjaro, sure I need to already know a fair amount about Linux but since I do its not a problem for me.

I dont know your situation or your personality I also dont know what you have to work with. If you have some old pos laptop or desktop your not using and are new to Linux maybe try Lubuntu. If you want to immerse yourself in pain and frustration but then come out the other end with a better understanding of Linux than your standard Ubuntu user maybe try Arch. If you run windows and maybe just want to play around with command line stuff you should install the Windows subsystem for Linux in your Windows enviornment.

Which shell should you use.

If your new to Linux or havent been using it for too long. I recommend Zsh. Then I recommend installing Oh-My-Zsh Then I recommend installing Powerlevel10k and configuring it the way you like it.

Configration files

Defaults

Logs

.bashrc .zshrc

Sources

exporting stuff

Add a new user on the system. (Provided you are root or have root access) The -m creates a new home directory for the new user also


sudo useradd -m newusername

Create a new password for the new user after the new user is created.


sudo passwd newusername

Need to push to multiple repositories from your machine using different ssh keys


GIT_SSH_COMMAND='ssh -i ~/.ssh/dconlrn' git push origin main

Show if your local repository is up to date ahead or behind a remote repo.


git remote update

then


git status -uno

Fail2ban

Text Editor Related

Nano

Vim

If you want to learn Vim through a playing a little game. Here you go.

Copy to clipboard

Enter visual mode Highlight the text

\ + y

to copy to paste

ctrl + shift + v or ctrl + alt + v

Nvim (Neovim)

Same as vim just looks cooler with a few more features

Spacevim

Vim/Neovim on crack!

crontab

Rsync

Generate an ssh 4096 bit encrypted rsa key

What ?

  • A special key used for secure communication between local and remote machines. Why ?
  • To make communication more seemless while still protecting the process.

Ex.

ssh-keygen -b 4096

Copy ssh key to a remote machine

What ?

  • Authorizes a remote machine allowing it to login without entering a password
  • Adds a trusted key into the authorized users file in /home/username/.ssh/authorized_keys Why ?
  • So you do not have to keep typing in your password when your sshing into a remote machine.

Ex.

ssh-copy-id -i ~/.ssh/id_rsa.pub username@192.168.5.38

File and folder permissions.

  • What the hell are they and what are they used for ?

Ranger

Compressing and decompressing files

Searching for or in files

Searching for or in folders

Apache

Apache SSL Certificate using Certbot on Arch Linux


sudo pacman -S certbot
sudo pacman -S letsencrypt
sudo pacman -S certbot-apache
sudo certbot install --cert-name mywebsite.net
sudo certbot install --cert-name 23.113.172.68
sudo certbot --apache
sudo certbot renew
sudo certbot certificates
cd /etc/letsencrypt/
sudo chmod 755 /etc/letsencrypt/live/
cd live
sudo chmod -R -v 755 /etc/letsencrypt/live/mywebsite.net/
mv fullchain.pem old.fullchain
sudo cat /etc/letsencrypt/live/mywebsite.net/fullchain.pem > fullchain.pem
mv privkey.pem old.privkey
sudo cat /etc/letsencrypt/live/mywebsite.net/privkey.pem > privkey.pem
rm cert.pem old.fullchain old.privkey

Nginx

Cool useful commands

Neofetch ttyd asciinema xfce4-screenshooter