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During this course you're going to write several shell scripts and learn a lot along the way.

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It's really important that you learn the concepts so that you can apply your knowledge on any Linux

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distribution or any Unix like or Linux like system.

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However when you're learning a new concept I don't want anything to get in your way.

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I don't want you to get hung up on little gotchas or get sidetracked by some unimportant detail.

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That's the main reason why you're going to use a specific Linux installation that was created for this

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course.

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Another reason you're going to use the Linux image design for this course is so that you can get help

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if everyone in the class were to use a slightly different Linux installation it would be almost impossible

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to manage the class if I or the teaching assistants know exactly what system you're using.

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We can help you in a very specific way we can even take your script and run it on a system that is the

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same as the one you're working on.

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This helps us help you.

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A third reason to use the Linux installation method I'm about to describe is that it will allow you

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to quickly create an entire mini network of Linux systems in the real world you'll end up writing shell

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scripts that perform a given task on multiple systems.

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This setup allows you to practice those skills and we're going to do that in this class.

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OK.

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So what does this installation method and lab setup that I've been alluding to for the last couple of

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minutes here and what this environment look like.

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First it consists of virtualization software that will allow you to run Linux inside a virtual machine

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on your local desktop or laptop.

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My favorite virtualization software for this purpose is virtual box available for download and Virtual

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Box dot org.

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First off it's free to download and it's really easy to install.

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Secondly it runs on Windows Mac and Linux.

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This is a big plus for a course like this as you're going to have the exact same experience no matter

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if you're working on a Windows system a Mac system or if you use Linux on your desktop every day.

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A little side note here if you're looking for a virtualization solution for running virtual machines

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in production for example I'd be looking at something like VM where KTM or overt.

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But for our purposes for creating test systems on our local machine and working together in this class

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virtual box is the way to go.

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Let's get clear on what virtual box does and what virtual machines are virtual box is a full virtualization

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product.

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Meaning that it allows you to run an unmodified operating system with all of its installed software

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in a special environment.

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On top of your existing operating system this special environment called a virtual machine is created

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by the virtualization software by intercepting access to certain hardware components and certain features

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the physical computer is called the host while the virtual machine is called a guest.

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Most of the guest code runs unmodified directly on the host computer and the guest operating system

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thinks it's running on a real machine.

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That last point is important.

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The guest operating system thinks it's running on real hardware and it really doesn't know that it's

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inside a virtual machine.

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If you're doing something inside a virtual machine in the operating system of them virtual machine says

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something like performing this action will erase all the data on all your disks.

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It's really only referring to the virtual disks that it has access to not your physical device on your

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real physical host computer.

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You can perform destructive actions inside the virtual machine and those actions are contained inside

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of that virtual machine and won't interfere with your actual physical computer.

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Virtual Box provides software that can be installed on the guest operating system.

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This software is called Virtual Box guest additions.

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This software allows the guest operating system to access shared folders on the host system share the

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clipboard and some other similar actions.

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This is not required but it can be very useful.

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The virtual machine you'll be deploying in this course will already have the guest addition software

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installed in them.

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I just wanted to mention the guest edition so that you're aware of them and know what they do manually

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creating virtual machines with virtual boxes fairly easy and straightforward.

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By the way we are not going to be manually creating machines in this course.

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I just want to show you the process so that you can do this on your own later or so that you know exactly

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what is happening behind the scenes when we automate this.

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So first you start the virtual box application and next you click on new to create a new virtual machine.

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From there you would give it a name virtual box a bit about the operating system that you'll be installing

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inside of the virtual machine and allocate some resources such as memory and disk space to the virtual

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machine.

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When you create a virtual desk for the virtual machine you can make it dynamically allocated a virtual

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disk is simply a file on the host system.

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When you choose to dynamically allocate that disk it will only use space on your physical disk as that

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space is used inside the virtual machine I guess this means that the disk file will grow as needed.

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The upside is that the virtual machine thinks it's getting a large disk such as 100 gigabyte or 200

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gigabyte.

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But if it only uses one gigabyte then only one gigabyte of space is used on your physical hard drive

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the price you pay for this dynamic allocation is performance inside the virtual machine.

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But for our purposes this is totally acceptable.

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Once you've allocated resources to the virtual machine it's ready to be used.

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And the first time you started up it will ask you to attach a disk to boot from.

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Typically what you'll do is download a Linux ISO from your favorite distribution's Web site and then

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tell virtual box to use that ISO to boot the system with.

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Alternatively you can actually put a physical CD or DVD in your computer and tell virtual box to use

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that physical drive for the install.

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Now you install the OS in the virtual machine just like you would as if you were installing that OS

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on real physical hardware.

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This process is all well and good but as you can probably guess it can be a bit time consuming.

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Going through the virtual machine creation process and manually performing the operating system installation

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each time you want to create a new virtual machine we're looking to automate this process and save us

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a lot of time doing that tedious work to do that we'll use a command line tool called vagrant which

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is available to download for free from vagrant up Tom.

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This command line tool works on Mac Windows and Linux so no matter what OS you're using for this course

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you'll be covered.

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Vagrant provides easy to configure reproduceable and portable work environments by default vagrant previsions

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virtual machines using Virtual Box.

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It can be configured to deploy virtual machines to VM where eight of us Rackspace and other providers.

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But for this course we're sticking to creating virtual machines inside a virtual box running on our

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local systems.

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You're going to use vagrant to quickly and easily spin up virtual machines running Linux.

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Let's talk about what you should know and understand about vagrant before you start using it.

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A box invigorates speak is an operating system image.

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The vagrant box ad command will download and store that box on your local system.

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You only need to download a box once as this image will be cloned.

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When you create a new virtual machine with vagrant using the boxes name the typical format of this command

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is vagrant box.

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Add user Ford slash box.

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I have a user account on vagrants public box catalog system my user name is Jason C..

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I created a box specifically for this course named Sentosa 7.

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It's really just a minimal Sentosa install so to demo that box you had run.

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Vagrant box and Jason see Ford slash Sentosa 7.

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There are several boxes that are publicly available on vagrants public box catalog system.

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I have a link in the exercise instructions where you can download other boxes if you'd like to experiment

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with them on your own time.

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In addition to boxes vagrant uses the concept of projects a vagrant project must consist of a folder

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and a vagrant configuration file called a vagrant file.

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So to create a new vagrant project first create a folder.

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For example I would open up a command prompt on Windows or a terminal on Linux or Mac and then type

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the command make DJR space VM one.

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From there you would change into that directory with CVM one.

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Now you need to initialize your vagrant project which means creating a vagrant configuration file his

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configuration file is named vagrant file and it contains the box name to use for the project and any

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other configuration options for the virtual machine or virtual machines to create to create the vigor

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and file run the vagrant init command.

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So continuing with our previous example here you would run vagrant a net.

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Jason C forward slash Cinto 7.

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Now you can bring up an instance of that box by running vagrant.

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Up the first time you run the vagrant up command vagrant will import or clone that vagrant box into

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virtual box and then start it.

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If vagrant detects that the virtual machine already exists in virtual box it will just simply start

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it by default when the virtual machine is started.

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It is started in headless mode meaning that there is no user interface for the machine visible on your

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local host machine.

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Since this class is focused on shell scripting will be working at the command line so we really don't

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care about looking at the Linux desktop anyway.

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Now if you look at the virtual box application you'll see that you'll have a new virtual machine that's

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running it's name starts with the name of the vagrant project which is the name of the director you

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created where the vagrant file lives.

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As I mentioned earlier you are going to be creating multiple virtual machines you can actually specify

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those additional virtual machines in the same vagrant file.

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This is called a multi machine setup by vagrant by default when you run the vagrant up command it brings

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up all the virtual machines defined in the vagrant file.

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If you only want to operate on a single virtual machine you have to supply the virtual machines name.

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For example if you defined a VM named M..

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You can bring it up with a vagrant a master command.

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Likewise if you had a VM defined with the name of server wan you would bring it up with vagrant up server

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one and I want to repeat that if you just Rannveig went up it would bring up both of those that word

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of find be caused by a fault.

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It brings up every system that's defined in the vagrant file for that vagrant project.

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SH secure shell is the network protocol used to connect to Linux systems vigor it provides a nice shortcut

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to S-sh into the virtual machines.

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If you only have one virtual machine defined in the bigger file you can simply run vagrant S-sh and

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emet the VM name and you'll be automatically logged into that one VM Linux system that you've created

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with vagrant.

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If you have multiple machines defined you'll need to supply the specific VM name for example vagrant

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S-sh master to log out of a Linux system simply type exit and hit enter.

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A quick note for you Windows users Windows doesn't currently ship with an S-sh client so you'll need

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to install one.

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And what I recommend doing is installing.

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Get that CGI tty from get dash SBM dot com which includes an S S H client.

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When you work on the exercise I'll give you specific instructions on how to get this configured but

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for you Mac and Linux users you can just skip this step as you already have an S-sh client built in

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by default.

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Ok back to vagrant vagrant can be used to control the virtual machines it creates.

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For example the vagrant halt command shuts down all the virtual machines defined in the vagrant file.

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If you have multiple victims to find and only want the whole one just specify the VM name when you run

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this command you will not lose any work you've performed inside the virtual machine.

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That's because the virtual machine will still exist in virtual box but it will just simply be halted

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or stop to restart all the defined VM for the project run.

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Vagrant up since the virtual machines already exist a vagrant Upal simply start them and it will skip

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the import process because it's not needed.

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By the way I'm pretty sure you see a pattern here with all these commands if you don't specify a VM

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name the command will operate on all the VM defined in the vagrant file for the project.

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If you want to limit that operation to a specific VM then you need to supply that name of the VM that

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you want to operate on.

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So going forward I'm just going to assume that you understand this concept and not point it out for

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each and every command.

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If you want to suspend the virtual machine run vagrant suspend to resume it run vagrant resume.

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If you're done with a virtual machine or you want to start over with a fresh copy of the virtual machine

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virtual machines run vagrant destroy.

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This will terminate and remove the virtual machine or virtual machines from Virtual Box.

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If you run this command then any work inside of the virtual machine will be lost.

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If you need help or forget some of the commands you can just run the vagrant command itself without

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any options.

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Also keep in mind that the vagrant command will act on the virtual machine or virtual machines associated

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with a vagrant project directory that you're in during this course she'll be creating multiple vagrant

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projects so be sure that you're in the desired vagrant project directory before running any vagrant

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command.

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Before we wrap up talking about vagrant Let's take a quick look at the vagrant file.

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All the vigor configuration occurs after the vagrant Dom configure line and before the end keyword the

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two in parentheses.

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Here is the configuration version.

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Older style configurations are supported but will be used in version 2.

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So this is what you'll see in the vagrant file you'll be working with.

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The simplest of vagrant file just specifies the name of the box you'll use to create the default VM.

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If you want vagrant to set the hostname inside the virtual machine you can use config dot VM dot hostname

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to assign a static IP address to the virtual machine.

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Use a config VM dot network line.

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The example on your screen will assign the IP address of 1:50 3.4 to the virtual machine on a private

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network that can only be accessed from the host machine or other vagrant VM.

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On that same network you'll be using this vagrant feature to create an entire network of Linux systems

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that can communicate with each other.

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Each box ships with a set of defaults like whether or not to star in headless mode or how much memory

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to allocate to the virtual machine and so on.

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You can override these default settings by using a config that VM up provider block.

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The example here on the screen will force the virtual machine to start with a gooey graphical user interface

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and use 1024 megabytes which is of course one gigabyte of memory.

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Vagrant has a provisioning system built in it.

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Pre-vis winners and vagrant allow you to automatically install software alter configurations and more

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on the machine as part of the vagrant process because we're focusing on shell scripting in this course.

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We'll use the show provision.

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You won't be using a provision or all the time but we will do this at some point during the course.

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This is where you can write a post installation shell script to configure a new system for example.

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Vigor will execute the shell script that you specify the first time vagrant upas executed.

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The example here on your screen will upload the setup that sh shell script into the virtual machine

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and then execute it from there.

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This way you can automate and reproduce entire environments quickly if you want to make sure someone

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else like a developer is working with the same configuration as you give them the vagrant file and the

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set up that sh script and they're set let's look at how to configure a multi machine set and vagrant

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if there is any common configuration to all the VM is just specify it at the top of the file.

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In this example we're going to use the same box or image for all the VM so we list it first.

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Next create a configuration block for the first VM.

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The syntax is shown on your screen.

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That's in Texas config that VM don't define and then you put a server name in quotation marks followed

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by do.

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And then in a set of pipes you also put the server.

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Then you set the VM specific configuration using that server any.

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This example sets the hostname an IP address for the VM.

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You keep adding additional victims using the exact same syntax on your screen a second VM is defined

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named server 2.

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If you were to run vagrant up using this configuration you would end up with two virtual machines one

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named server one with an IP address of 10.

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Two of three to four.

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And another one named server 2 with an IP address of 10 to 3.5.

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We've talked about many of the awesome things vagrant can do and many of the vagrant features you'll

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be using most often.

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However there is more the vigor and it can and creates a default vagrant file which contains several

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comments.

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You can read through those comments to get an idea of what else is possible with vagrant.