# Hello world

Welcome!


Essential: introduction to linux
=================

* [Introduction to Linux](./essential/introduction_to_linux.md#introduction-to-linux)
   * [Where does Linux originate from?](./essential/introduction_to_linux.md#where-does-linux-originate-from)
   * [Who is behind this project?](./essential/introduction_to_linux.md#who-is-behind-this-project)
   * [What is the deal with 'GNU-slash-Linux'?](./essential/introduction_to_linux.md#what-is-the-deal-with-gnu-slash-linux)
   * [Where can you <em>get</em> some Linux?](./essential/introduction_to_linux.md#where-can-you-get-some-linux)
   * [Debian](./essential/introduction_to_linux.md#debian)
* [How to create a virtual machine](./essential/introduction_to_linux.md#how-to-create-a-virtual-machine)
* [Breakdown of the Debian installation](./essential/introduction_to_linux.md#breakdown-of-the-debian-installation)
* [Exercise](./essential/introduction_to_linux.md#exercise)
* [Quick look at an idle system](./essential/introduction_to_linux.md#quick-look-at-an-idle-system)
* [Package managers](./essential/introduction_to_linux.md#package-managers)
   * [Graphical installation](./essential/introduction_to_linux.md#graphical-installation)
   * [Command line installation](./essential/introduction_to_linux.md#command-line-installation)
   * [Adding a secondary desktop environment](./essential/introduction_to_linux.md#adding-a-secondary-desktop-environment)
* [Changing the runlevel](./essential/introduction_to_linux.md#changing-the-runlevel)
* [Exercise](./essential/introduction_to_linux.md#exercise-1)
* [Guest additions](./essential/introduction_to_linux.md#guest-additions)

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Essential: introduction to the commandline
=================

* [Introduction to the command line](./essential/introduction_to_the_commandline.md#introduction-to-the-command-line)
   * [Compiled vs interpreted](./essential/introduction_to_the_commandline.md#compiled-vs-interpreted)
   * [Note on file extensions](./essential/introduction_to_the_commandline.md#note-on-file-extensions)
* [More about paths](./essential/introduction_to_the_commandline.md#more-about-paths)
   * [Absolute and relative paths](./essential/introduction_to_the_commandline.md#absolute-and-relative-paths)
   * [root and  / and /root are not the same thing](./essential/introduction_to_the_commandline.md#root-and---and-root-are-not-the-same-thing)
* [Exercise](./essential/introduction_to_the_commandline.md#exercise)
* [A pit stop to review what we've learned so far](./essential/introduction_to_the_commandline.md#a-pit-stop-to-review-what-weve-learned-so-far)
* [Arguments and flags](./essential/introduction_to_the_commandline.md#arguments-and-flags)
* [Getting help](./essential/introduction_to_the_commandline.md#getting-help)
   * [Options](./essential/introduction_to_the_commandline.md#options)
   * [Manuals](./essential/introduction_to_the_commandline.md#manuals)
   * [Exercise](./essential/introduction_to_the_commandline.md#exercise-1)
* [Creating, modifying and deleting](./essential/introduction_to_the_commandline.md#creating-modifying-and-deleting)
   * [Directories](./essential/introduction_to_the_commandline.md#directories)
   * [Files](./essential/introduction_to_the_commandline.md#files)
   * [Links](./essential/introduction_to_the_commandline.md#links)
* [Editors](./essential/introduction_to_the_commandline.md#editors)
   * [nano](./essential/introduction_to_the_commandline.md#nano)
      * [Exercise](./essential/introduction_to_the_commandline.md#exercise-2)
   * [vi and vim](./essential/introduction_to_the_commandline.md#vi-and-vim)
      * [Exercise](./essential/introduction_to_the_commandline.md#exercise-3)
* [Opening or peaking into files](./essential/introduction_to_the_commandline.md#opening-or-peaking-into-files)
* [Exercise](./essential/introduction_to_the_commandline.md#exercise-4)
* [Finding stuff](./essential/introduction_to_the_commandline.md#finding-stuff)
   * [Finding files](./essential/introduction_to_the_commandline.md#finding-files)
      * [The easy way](./essential/introduction_to_the_commandline.md#the-easy-way)
      * [The hard way](./essential/introduction_to_the_commandline.md#the-hard-way)
* [Exercise](./essential/introduction_to_the_commandline.md#exercise-5)
* [Searching inside files](./essential/introduction_to_the_commandline.md#searching-inside-files)
   * [Wild cards and regular expressions](./essential/introduction_to_the_commandline.md#wild-cards-and-regular-expressions)
      * [Wild cards](./essential/introduction_to_the_commandline.md#wild-cards)
* [Exercise](./essential/introduction_to_the_commandline.md#exercise-6)
* [Exercise](./essential/introduction_to_the_commandline.md#exercise-7)
      * [Regular expressions](./essential/introduction_to_the_commandline.md#regular-expressions)
* [Pipes and redirects](./essential/introduction_to_the_commandline.md#pipes-and-redirects)
   * [Redirecting](./essential/introduction_to_the_commandline.md#redirecting)
      * [Input redirection](./essential/introduction_to_the_commandline.md#input-redirection)
   * [Piping](./essential/introduction_to_the_commandline.md#piping)
* [Text manipulation](./essential/introduction_to_the_commandline.md#text-manipulation)
* [Ideas](./essential/introduction_to_the_commandline.md#ideas)
* [Exercises](./essential/introduction_to_the_commandline.md#exercises)
   * [Mini exercise 1](./essential/introduction_to_the_commandline.md#mini-exercise-1)
   * [Mini exercise 2](./essential/introduction_to_the_commandline.md#mini-exercise-2)
   * [Mini exercise 3](./essential/introduction_to_the_commandline.md#mini-exercise-3)
   * [Mini exercise 4](./essential/introduction_to_the_commandline.md#mini-exercise-4)
   * [Mini exercise 5](./essential/introduction_to_the_commandline.md#mini-exercise-5)
   * [Mini exercise 6](./essential/introduction_to_the_commandline.md#mini-exercise-6)
* [Ideas](./essential/introduction_to_the_commandline.md#ideas-1)

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Essential: introduction to administration
=================

* [Users](./essential/introduction_to_administration.md#users)
   * [Adding and removing users](./essential/introduction_to_administration.md#adding-and-removing-users)
      * [GNOME](./essential/introduction_to_administration.md#gnome)
      * [command line](./essential/introduction_to_administration.md#command-line)
   * [Switching user](./essential/introduction_to_administration.md#switching-user)
   * [Groups](./essential/introduction_to_administration.md#groups)
* [Permissions](./essential/introduction_to_administration.md#permissions)
   * [Octal number system](./essential/introduction_to_administration.md#octal-number-system)
   * [Changing ownership](./essential/introduction_to_administration.md#changing-ownership)
   * [umask](./essential/introduction_to_administration.md#umask)
   * [Essential programs](./essential/introduction_to_administration.md#essential-programs)
* [Remote control of a server](./essential/introduction_to_administration.md#remote-control-of-a-server)
   * [History](./essential/introduction_to_administration.md#history)
   * [SSH and SFTP](./essential/introduction_to_administration.md#ssh-and-sftp)
* [Bandit](./essential/introduction_to_administration.md#bandit)

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Advanced: learning bash scripting
=================

* [bash](./advanced/learning_bash_scripting.md#bash)
* [Using variables to store the output of command](./advanced/learning_bash_scripting.md#using-variables-to-store-the-output-of-command)
* [Coding challenge - Output system stats](./advanced/learning_bash_scripting.md#coding-challenge---output-system-stats)
* [Getting input into the script](./advanced/learning_bash_scripting.md#getting-input-into-the-script)
   * [With read](./advanced/learning_bash_scripting.md#with-read)
* [Coding challenge - Secret input](./advanced/learning_bash_scripting.md#coding-challenge---secret-input)
      * [read multiple variables](./advanced/learning_bash_scripting.md#read-multiple-variables)
         * [Exercise - unpack values](./advanced/learning_bash_scripting.md#exercise---unpack-values)
   * [With command line arguments](./advanced/learning_bash_scripting.md#with-command-line-arguments)
* [Coding Challenge - output the exact output below](./advanced/learning_bash_scripting.md#coding-challenge---output-the-exact-output-below)
* [More math!](./advanced/learning_bash_scripting.md#more-math)
   * [The let keyword](./advanced/learning_bash_scripting.md#the-let-keyword)
   * [The expr keyword](./advanced/learning_bash_scripting.md#the-expr-keyword)
   * [Double parenthesis](./advanced/learning_bash_scripting.md#double-parenthesis)
   * [Variable length](./advanced/learning_bash_scripting.md#variable-length)
* [If Statements - How to make decisions within your Bash script.](./advanced/learning_bash_scripting.md#if-statements---how-to-make-decisions-within-your-bash-script)
   * [How does it work behind the scenes?](./advanced/learning_bash_scripting.md#how-does-it-work-behind-the-scenes)
   * [exit status](./advanced/learning_bash_scripting.md#exit-status)
   * [test](./advanced/learning_bash_scripting.md#test)
   * [Nested if statements](./advanced/learning_bash_scripting.md#nested-if-statements)
   * [A <em>modern</em> version of test](./advanced/learning_bash_scripting.md#a-modern-version-of-test)
      * [[[  ]]](./advanced/learning_bash_scripting.md#--)
      * [((  ))](./advanced/learning_bash_scripting.md#---1)
      * [&amp;&amp; and  ||](./advanced/learning_bash_scripting.md#-and--)
* [Coding challenge - File information](./advanced/learning_bash_scripting.md#coding-challenge---file-information)
* [Coding challenge - pipe or argument?](./advanced/learning_bash_scripting.md#coding-challenge---pipe-or-argument)
* [Loops - A variety of ways to perform repetitive tasks.](./advanced/learning_bash_scripting.md#loops---a-variety-of-ways-to-perform-repetitive-tasks)
   * [while loop](./advanced/learning_bash_scripting.md#while-loop)
      * [Read from a file with a while loop](./advanced/learning_bash_scripting.md#read-from-a-file-with-a-while-loop)
      * [Read from a pipe with a while loop](./advanced/learning_bash_scripting.md#read-from-a-pipe-with-a-while-loop)
   * [for loop](./advanced/learning_bash_scripting.md#for-loop)
      * [Counter loops with for](./advanced/learning_bash_scripting.md#counter-loops-with-for)
      * [Finicky behaviour](./advanced/learning_bash_scripting.md#finicky-behaviour)
   * [break and continue](./advanced/learning_bash_scripting.md#break-and-continue)
* [Coding challenge - pipe or argument plus action!](./advanced/learning_bash_scripting.md#coding-challenge---pipe-or-argument-plus-action)
* [Coding challenge - Rename files](./advanced/learning_bash_scripting.md#coding-challenge---rename-files)
* [Coding challenge - Rename jpeg files](./advanced/learning_bash_scripting.md#coding-challenge---rename-jpeg-files)
* [Coding challenge - Remove duplicate files](./advanced/learning_bash_scripting.md#coding-challenge---remove-duplicate-files)
* [Coding challenge - File tree](./advanced/learning_bash_scripting.md#coding-challenge---file-tree)
* [Coding challenge - Compare and move](./advanced/learning_bash_scripting.md#coding-challenge---compare-and-move)
* [Coding challenge - Guess the number](./advanced/learning_bash_scripting.md#coding-challenge---guess-the-number)
* [Functions - Reuse code to make life easier.](./advanced/learning_bash_scripting.md#functions---reuse-code-to-make-life-easier)
   * [defining a function](./advanced/learning_bash_scripting.md#defining-a-function)
   * [function arguments](./advanced/learning_bash_scripting.md#function-arguments)
   * [global vs local variable](./advanced/learning_bash_scripting.md#global-vs-local-variable)
   * [return values](./advanced/learning_bash_scripting.md#return-values)
   * [the command builtin](./advanced/learning_bash_scripting.md#the-command-builtin)
* [Coding challenge - Student reports](./advanced/learning_bash_scripting.md#coding-challenge---student-reports)
* [User Interface - Make your scripts user friendly.](./advanced/learning_bash_scripting.md#user-interface---make-your-scripts-user-friendly)
* [Coding challenge - Address book](./advanced/learning_bash_scripting.md#coding-challenge---address-book)
* [Arrays in bash](./advanced/learning_bash_scripting.md#arrays-in-bash)
   * [Python](./advanced/learning_bash_scripting.md#python)
   * [Vim as an IDE](./advanced/learning_bash_scripting.md#vim-as-an-ide)

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Advanced: learning shells
=================

* [bash login](./advanced/learning_shells.md#bash-login)
   * [which files are sources when](./advanced/learning_shells.md#which-files-are-sources-when)
* [A clean slate](./advanced/learning_shells.md#a-clean-slate)
* [Prompt customization](./advanced/learning_shells.md#prompt-customization)
   * [Saving our changes](./advanced/learning_shells.md#saving-our-changes)
   * [Decoding the <em>base</em> prompt](./advanced/learning_shells.md#decoding-the-base-prompt)
* [Alternative shells](./advanced/learning_shells.md#alternative-shells)
   * [zsh](./advanced/learning_shells.md#zsh)
   * [fish](./advanced/learning_shells.md#fish)
   * [xonsh](./advanced/learning_shells.md#xonsh)
* [Shell completion](./advanced/learning_shells.md#shell-completion)
* [Frameworks](./advanced/learning_shells.md#frameworks)
   * [oh my zsh](./advanced/learning_shells.md#oh-my-zsh)
   * [oh my bash](./advanced/learning_shells.md#oh-my-bash)
* [xxh](./advanced/learning_shells.md#xxh)

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