diff --git a/essential/readme.md b/essential/readme.md
index 68abc88..3ab5867 100644
--- a/essential/readme.md
+++ b/essential/readme.md
@@ -11,7 +11,7 @@
### Who is behind this project?
* Who is [Richard Stallmann](https://en.wikipedia.org/wiki/Richard_Stallman)?
-* Who is [Linux Torvalds](https://en.wikipedia.org/wiki/Linus_Torvalds)?
+* Who is [Linus Torvalds](https://en.wikipedia.org/wiki/Linus_Torvalds)?
### What is the deal with 'GNU-slash-Linux'?
@@ -39,25 +39,59 @@
## How to create a virtual machine
-Step by step walk-through of a VM creation in virtualbox with some notes on each step with best practice pointers.
+In order to run virtual machines, or VM's, we need a **host** program.
+One of the most popular ones out there is called `virtualbox`.
+It should be installed on your machine but in case it's not you can download it [here](https://www.virtualbox.org/wiki/Downloads).
+If you **expand** the section below you'll see a step by step walk-through of a VM creation in virtualbox with some notes on each step with best practice pointers.
+
+ Expand me...
+
+**Nice!**
+
+1. Name your machine and select *linux* if it's not chosen automatically.
+1. Set the amount of RAM for your machine.
+This can be anything between an absolute minimum and your physical machine's limit.
+You can't *magically* use more RAM than physically available!
+1. You need a virtual hard drive to store the OS and all your data to.
+1. The format doesn't matter that much.
+I always go for the default one.
+1. Most of the time you'll want dynamic size meaning the disk **file** will only take up as much **space** as it needs.
+For example, if you set a size of 50GB for your disk and your OS plus personal files take up 12GB, the actual space this image takes op on the physical disk of your **host** will be about 12GB.
+1. We'll soon discover **how much space** a basic Linux installation takes up but for now I would recommend the following.
+ * **with** a graphical environment: 20GB
+ * **without** a graphical environment: 10GB (minimal/server/headless install)
+1. By default your machine will have only **one** CPU core but you can add more via the settings.
+This is something you can change whenever you need more processing power but the same rule as with the RAM applies, it's not a magical way to add resources to your machine.
+1. Last but not least we need to insert the installation disk into the virtual machine and boot it up!
+
## Breakdown of the Debian installation
All right, enough talking, let's get started!
I'll install a full blown and modern graphical Debian machine and I would like you to **not** do it yourself but take **notes** on each step so you'll be able to reference your notes later **when** I ask you to install a machine yourself.
+Below is a gain a step by step walk through with some of my tips but a more details guide can be found in the [Debian Administrator Handbook](https://debian-handbook.info/browse/stable/sect.installation-steps.html).
+This book is a real *bible* of information and I highly advise you to read through it.
-* [step by step](https://debian-handbook.info/browse/stable/sect.installation-steps.html) installation instructions
- * **don't set a root password, use `sudo` instead**
- * **stress the graphical/minimal difference**
+My most important notes would be the following.
+
+* **Read** each section carefully and you'll know what to do.
+* Don't set a root password but use `sudo` instead.
+* Don't install a graphical environment if you don't need one.
+It's a lot easier to add one later than to remove it.
+* Don't forget to install `grub` at the end otherwise your installation will not be able to boot.
+You *can* recover from this mistake with [supergrub2](https://www.supergrubdisk.org/super-grub2-disk/) but that's for an other day.
+
+
+ Expand me...
@@ -91,6 +125,7 @@ I'll install a full blown and modern graphical Debian machine and I would like y
+
### Exercise
@@ -103,22 +138,48 @@ Can you install extra software?
## Quick look at an idle system
+You can inspect the system by running the *gnome task manager*.
+It lists all your running processes, sorted by CPU percentage, in the first tab which can give you a good idea of what's happening on your system.
+Note that an idle system uses almost **no resources**!
+Plus, a fresh install, with quite a few essential programs such as a browser, music player, text editor, etc only takes up about 5GB of disk space!
+This is mind blowing compared to a windows installation.
+How is this possible?
+That's the magic of a good package manager!
+
+
+ Expand me...
+
+
## Package managers
-* what is a [package manager](https://en.wikipedia.org/wiki/Package_manager)
+What is a [package manager](https://en.wikipedia.org/wiki/Package_manager)
### Graphical installation
+Modern Linux has come a long way and it's now quite usable without any command line knowledge.
+We can install extra software from the graphical environment if we want.
+
+Let's look for `vlc`, a popular open source video player.
+When we look for it from `activities` we *see* a reference to it via the `software` program.
+If we click on it we'll be take to a sort of *app or play store* where we can choose to install or uninstall programs.
+Because adding and removing software from our machine is quite *invasive*, we need to **prove** we have the right to do so.
+A prompt will pop up where you'll need to input **your** password.
+If your password does not work, you probably set a `root` password and you should use that one instead.
+
+
+ Expand me...
+
+
### Command line installation
@@ -245,8 +306,11 @@ waldek@hellodebian:~$ sudo reboot now
Please create a second virtual machine and install a **minimal** Debian.
Minimal means **no graphical environment**.
I advise you to **not** set a root password.
+
Once this machine is up and running, install a few programs.
The only one we saw up until now is `htop` but maybe try out `bmon`, `elinks` and/or `ranger`.
+Once these are installed have a look at the running services and programs via `htop` and compare it to both your graphical installation **and** your graphical install but running in `multi-user.target`.
+
## Guest additions
@@ -354,7 +418,7 @@ You can also enable copy/paste and drag and drop between your host and VM now.
We'll be using a few new *words* to reference the command line such as *shell*, *bash* and *terminal* through out the course.
They all pretty much mean the same thing but with some small, and not so important, differences between them.
Essentially a command line is a **textual interface** for humans to operate a computer.
-What is very important to understand is that textual command and graphical actions operate on the same computer.
+What is very important to understand is that textual commands and graphical actions operate on the **same** computer.
For example, if you create a file via the command line, it will show up in you file explorer and vice versa.
The graphical and textual interfaces are just different *representations* of the same machine.
@@ -410,5 +474,55 @@ But what happens if you **close** vlc?
The commands you typed get executed!
This is an illustration of the **sequential** nature of a command line.
+Now, I don't think we have sufficiently *proven* that `date` is a full blown program so let's dig a bit deeper.
+```
+waldek@hellodebian:~$ which vlc
+/usr/bin/vlc
+waldek@hellodebian:~$ which date
+/usr/bin/date
+waldek@hellodebian:~$ which which
+/usr/bin/which
+```
+There is quite bit to *unpack* in the example above.
+First, what on earth is `which`?
+Well, it's *also* a program and it's sole purpose in life is to tell you **where** a program is located on your system.
+Because `which` by itself does not make a lot of sense it needs what we call an **argument**.
+Here the argument is the name of the program we want to know it's location of.
+The existence of arguments is the second big thing we discovered here.
+The third new thing we can observe here is what we call **paths**, meaning locations on the system.
+For example, `vlc` is a *binary* program located in a **folder** called `bin` which is located in a folder called `usr` which is at the *root* of your system.
+If this sounds complicated, don't worry, we'll go into detail a bit later.
+
+Now that we know **where** some of our programs are located, let's find out **what** they are.
+The methodology is the same as with `which` but we'll use an other program called `file` who's purpose in life is to tell more about the **content** of a certain file.
+Logically, `file` needs an argument and this argument is the **path** to the file you want to inspect.
+
+```
+waldek@hellodebian:~$ file /usr/bin/vlc
+/usr/bin/vlc: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=51c40f8234213415771b3a344cab25a140543f8a, for GNU/Linux 3.2.0, stripped
+waldek@hellodebian:~$ file /usr/bin/date
+/usr/bin/date: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=b740f054aaef6a85aff024858c914c7eae70a6a5, for GNU/Linux 3.2.0, stripped
+waldek@hellodebian:~$ file /usr/bin/which
+/usr/bin/which: POSIX shell script, ASCII text executable
+waldek@hellodebian:~$ file $(which which) # this is some command line kung fu...
+/usr/bin/which: POSIX shell script, ASCII text executable
+waldek@hellodebian:~$
+```
+
+Here we learn that both `vlc` and `date` are **executables**, compiled for an x86-64 system.
+I would say they are both created *equally* no?
+Both are actual programs.
+But what about `which`?
+It's also an executable but not compiled, it's a *POSIX shell script*.
+So not all programs *are* created equally?
+
+### Compiled vs interpreted
+
+Executing a file, or program, means you take this file and tell the computer it needs to execute the actions that are stored in the file.
+Compiled programs contain actual [instructions](https://en.wikipedia.org/wiki/Instruction_set_architecture#Instructions) the computer understands out of the box.
+This means that programs that are compiled are always compiled for a specify architecture which in our case is x86-64.
+On a Raspberry Pi this would be armhf or arm64.
+
+## `root` and `/` and `/root` are not the same thing