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Hey guys and welcome back.

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So in this skill right here we're going to be focusing on the Linux file system and we

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will focus that tension around the basic operations of the Linux file system.

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So the first thing we will talk about is how the Linux file system is actually structured

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its basic architecture and then we will talk about being able to mount particular file

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systems on our system.

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So there are two different ways that we can actually mount our system we can mount it

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in a manual way whereby we have to go in via the CLI and type in some particular commands

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and specify what it is we are looking to mount and where the mount point should be.

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We will cover that within this skill right here but we will also talk about how we can

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automatically do this process and also what we're going to cover is dealing with swap

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space very very important with the management of our system.

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So a lot of cool things to get to within this skill right here the very first thing I want

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to talk to you about is that Linux file system how about we roll up our sleeves and get going

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then.

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When we are talking about a file system what is it we actually mean here this might be

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a quite esoteric term if you haven't really dug in and explored it.

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Now we have two different branches of file system that we can have the very first one

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is a physical file system and the second type happens to be a virtual file system.

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So what do we mean when we talk about a physical file system.

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Now a physical file system are really just used to store data and organize that data

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on a device so that may be something like say for example a RAID device now we actually

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haven't really dived into RAID quite just yet but we use RAID as a form of redundancy

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within our system administration.

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However it doesn't have to be a RAID device it could be a particular partition on a device

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and more but when we are talking about a virtual file system how in earth does that actually

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differ.

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Well really when we are talking about a virtual file system what we are talking about are

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what the end users actually interact with when they happen to be using the particular

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operating system so that if you happen to go in via the CLI and we do an LS and we go

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into a directory and you access a particular file what we are actually doing here is working

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with the virtual file system.

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Now the reality is the virtual file system itself is actually utilizing physical file

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systems so the virtual file system is how we are actually interfacing with the system

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but it will be pulling information from real live devices real partitions you know say

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for example this could be disc 1 which is a hard disk and then maybe an SSD here as

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well we are pulling from these physical file systems and presenting it to the user via

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the virtual file system where they can actually interact with this information.

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Now here is the thing what we actually do is we ultimately carve up our system and we

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carve it up into different partitions so this might be one partition this might be a second

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partition so on and so forth but one thing we have to do is we have to put a file system

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onto the partition.

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Now we do have some different file systems that we can actually put onto a partition

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and we will mention what they are very very shortly but understand right now we have a

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disk we can carve it up into partitions and we want to put file systems onto that partition.

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Now here is the rub just by simply carving up a disk like so and putting a file system

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onto a partition it does not mean the end user can actually access that file system if

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we want to be able to access a particular file system we have to mount it and once we actually

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mount the file system that will present that file system to the end user so that they can

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actually interact with that file system otherwise it just is like I say inaccessible.

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Now this is what I am talking about when I am referencing the physical file system and

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the virtual file system with respect to Linux we have what we know is a directory tree structure

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so if I go to the root directory if I happen to type the command tree we are going to see

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a very very massive tree like structure.

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This presents way too much information if I just limit the output here just so we only

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go to folders down and to enter if I scroll on up you can actually see the relationship

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going on at the very top of the tree we have this root directory and within that we have

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the bin directory and the boot directory and then the cd rom and you know within these

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directories there are files and further directories this is the directory tree we are talking about

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so when we want to mount a particular file system we want to mount it somewhere within

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this directory tree like structure so you know as we saw there we could have our root

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directory right here and then branching off we may have say for example the boot directory

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and at the same level we may have you know like to say the dev directory so on so forth.

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Now the reality is the way this actually works is that different disks are mounted at different

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points in the directory structure so right here in my situation right here at the root

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directory we have sda5 so this is the first disk and it's partition number five that

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is actually accessible when I go to the root directory however when I switch and go to

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the boot directory I'm actually accessing sda1 so I'm accessing the same disk but I'm

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actually accessing a completely different partition so think about this okay we have

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this disk here disk1 okay but it is partitions so when I'm in the root directory I'm actually

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accessing this big portion of the disk this large chunk here okay all this part here however

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just by simply typing the command cdboot I move into the boot directory and that is

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actually mounted within a different partition so think about what is actually happening

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just by me typing the command cd I'm working through the virtual file system but under

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the hood I'm actually accessing different partitions or it may even be different disks

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entirely however I choose to mount a particular file system it could be from a hard disk and

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then I cd into another directory and now suddenly I may be transparently accessing a solid state

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drive so this really is what is happening when we are utilizing our virtual file system it allows

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us to easily move around transparently so like I say I go into the root directory I do an LS

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right now I'm accessing partition five I go into cdboot suddenly I'm now accessing partition

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number one but to you as the end user it is presented to you as the virtual file system and

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all of this switching around between physical devices happens really without your knowledge

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behind the curtain under the hood now if you happen to be using maybe say a windows device you

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might notice things are a little bit more explicit you can see here we have clearly delineated disks

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c and we could go in and browse through that disk or we could go into disk d which is another

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disk entirely and then browse files within that but it's much more explicit when we happen to use

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the linux file system you could just be changing directory quickly and be flipping through disks

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without ever really knowing about it so one thing I would say is that when we want to mount a

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particular file system it is very important that we mount this within a directory within the

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directory tree structure and we want that directory to be empty now the reason why is this and it's

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not because you can't mount into a directory which does have particular files or further

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directories further sub directories should I say it's just that if you happen to mount into a

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directory which already has files and folders those files and folders will suddenly become

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inaccessible not that they're deleted or anything like that it just means that while the file system

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happens to be mounted in that directory you're not going to be able to access anything within that

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that existed prior so imagine if you happen to have some important files some critical files

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and you mount a file system into that very same directory those critical files you're not going

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to be able to touch them until you unmount that file system so really it's not an enforced rule it

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just really is something that you want to self impose for your own best practice so think about

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this as I say we have the root directory and then we could have you know the boot directory and you

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will know that I have a home directory you know cd home and within my home directory I have a folder

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under my username called ipv0 and within this directory here if I so chose I could just use

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the command mkdir to create a new directory maybe just call this backup and make it an empty directory

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and what I could do I could have another disk and mount that disk within this directory right here

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so this may be bsdb partition one whereas the root directory that would be sda partition five

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and the boot directory is going to be sda partition one so that means if we go to our root

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directory we are on the first disk partition five if we go down to our home directory we're still on

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disk one partition five same again if we go into the ip0 folder but if we happen to go into this

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newly created backup directory suddenly and transparently we would be reading from an

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entirely separate disk and the first partition of that disk however if we go back out to ipv0 we

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once again are on sda five but if we go into the boot directory we would be on the same disk again

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sda one i.e the first disk but we would now be switching to that first partition so I really

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really really just want that process to be very very clear because very often people tend to get

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a little bit confused when first presented with this information but once you get it you absolutely

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get it and it does make sense and stick that is the good news so I did say we would have a word

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about the file systems that are in play what type of file system can we actually utilize with respect

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to linux now we will actually mention these file systems in a little bit more detail later on

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within this very course but I do just want to give you a brief summary so we have the file system

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ex t2 this is based on the extended file system the original one ex t but this was an improvement

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okay and again we'll talk about what those improvements are a little bit later on within

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this course next we had ex t3 again an improvement over its predecessor ex t2 and this allowed a

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type of logging feature known as journaling why that is important again we will certainly see that

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very very shortly then we have ex t4 this again provided the benefits of ex t3 i.e we still get

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journaling but it provides other features very important features such as allowing for much

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larger file systems and this one happens to be a very common file system used in modern linux systems

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now moving on from the ex t file systems we also have the xfs file system this one is all about

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high performance that really was the design goal of this file system and it does live up to its

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promise next we have what is called the btrfs this again is all about size and this was designed

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to deal with very very large data devices so large large large and like i say we do have even

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more file systems to explore later on now i just wanted to mention the different types of file

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system because right now in order to demonstrate the mounting and unmounting of our file systems

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as we move throughout this very skill what i want to do is to actually add another disk entirely

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now you can actually do this on different types of virtual machines vmware if you so choose

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i happen to have a virtual box device or a virtual box instance should i say so i'm just going to

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add that right now so what i'll do here is i'll just minimize this and i'll open up virtual box

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in fact before i do anything what i'm going to do is i'll shut down my machine forgetting the

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sudo command that has always type in the passwords okay so that should be shutting down the machine

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what i will do is i'll go to my virtual box machine right now and i'm going to click the

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settings button okay now if i go to storage and i choose sata what i'm going to do is to click

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this icon here add new storage attachment if i click this i'm going to choose a hard disk now

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what i'll do here is i'll just click create right now and i'll choose next here i'll make it a

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dynamically allocated hard disk i'll just make the size maybe just say i don't know like one gig

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or something like that doesn't really matter the size so much and i will create this now what i will

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do is i'll scroll on down i will select this option right here vdi we can actually see the size right

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here and i will click choose so now i've actually added a second disk so what i will do now is i'll

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click okay and then i'll turn back on my machine so i'll click start right here and the machine is

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just powering on okay so i'll go in and open up a terminal right here so if i go in to my dev

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directory right now and i do an ls in fact let me just grep for sd and remember the grep command

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john there we go so what we can now see here is because i've added this second disk i don't just

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have sda1 which has these different partitions i have this new one here sdb this is the second

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disk i've just added now what i want to do here is i actually want to give this disk a partition

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because right now it's just sdb no partitions available now the command i can use to give this

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disk a partition is fdisk so what i will do here is i'll just say sudo fdisk and i'll do dash l for

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a list type in my passwords and we can see here like i say the very first disk right here it has

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partitions this one here no partitions at all as of yet so the name is sdb and this is what we're

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going to use we're going to say sudo fdisk and i'll say dev sdb so if i hit enter here notice it says

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we have to type a particular command now the command i can use is the m command for help so i'll say

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m and then enter and if we scroll on down or rather scroll on up we can see these different options

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here so if i do l we can actually see the partition types so i can say l here hit enter so the partition

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type i would like would be 83 which would be for linux so what i'll do is i'll say m for help again

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if i say n this will allow me to create a new partition so i'll say n right here the type of

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partition i want i will have a primary partition i'll say p and hit enter the partition number if

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i have the default one that means we will have sdb one the first partition so i'll just say one

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and to enter the first sector 2048 leave it at default the last sector again leave at the default

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now it is auto detected the type as linux and it's going to be the entire size of the disk 1.2 gig

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now if i actually want to keep these changes and write them so that they do take effect what i need

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to do is to say w because as we see here this is going to allow us to write the table to disk and exit

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so that's exactly what i'll do so now the partition has been created if i do sudo fdisk dash l notice

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now we have a little number on the end sdb one we now have a partition and now that we have a

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partition we want to give this partition a file system now like i say i'm not going to go into

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too much detail in this command right now we'll talk about file systems in more detail but we did

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see that we have a file system called ext4 and i'm going to use this command to make a file system

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using ext4 so i'll say mkfs.ext4 and then i'll just target the partition so it's in the dev

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directory it's going to be sdb which is my new disk and partition number one that is the partition

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we want to put this file system onto so if i enter now now we should have a file system here if i do

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my fdisk dash l we have a partition we have the type of linux and we are ready to use this partition

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with this file system and we can begin practicing the mounting and unmounting of this partition

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in different locations within our virtual file system so that was a lot to get to in the opening

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of this skill the next thing we're going to be tackling is manually mounting this new partition

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or this new file system using the mount command and that's what we're going to be doing in the

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very next nuggets i hope it's been informative for you and i'd like to thank you for viewing