EX200 Red Hat Certified System Administrator RHCSA – The Red Hat Linux file system explained and basic functions

1. Linux file system explained where all files are in the root directory

Welcome all. Today I am going to start talking about the Linux file system. I want to explain it and I want to show you its architecture. Now if you have worked before with Windows you might have noticed that you have a C partition always and then on a C partition you have all the system files and you can’t actually go to the root of the system. Rather instead you can go to the partitions of the system and on C drive that is considered to be the root of the system. Such is not the case in Linux. In Linux you have a root of the file system where everything is contained regardless of the disk partitions and disks themselves.

So you can have multiple disks with multiple partitions but they will all be in the main route of the file system. Well, not directly there, but from there you will be able to navigate to it. If you go ahead and type in CD you’re going to be taken to the root of the file system and then from there type in LS and you will see these directories this is the file structure here. That is the key to pretty much everything else. Let’s go one by one over these folders. They are quite important and you should know what is contained in each one of them.

You don’t have to know exactly what is contained in each one of them but you do need to have a general idea of what sort of things are stored in each one of these folders. If we go ahead and start from bin in bin, system binaries are stored and by that I mean programs. Basically programs that are used by the system are stored in bin.

So system programs not to say that you can’t use them either. Under Dev we have devices so let’s just go ahead and quickly see what is in bin and what is in devices. By the way, dev is actually a virtual directory. There a listing of our hardware. When it is loaded, it is listed there. I’m going to show you in a moment what I mean by it. So in bin you see we have these commands here I’m not sure if we actually okay, so M copies there we go we have Yum, which we use to install packets. Not sure if we have anything familiar here there we go, we have LS.

So you see these are the sort of programs that are stored here. If we go ahead and type in LS no, sorry, go back and then let’s go into Dev. And if we do LS here you will see that this is actually our hardware. I’m sure that you can recognize some of the devices from the list without much thinking but if I go up this one probably won’t be an obvious one.

This is actually my CDROM drive. This is where I would insert a CD basically in a physical sense in the physical world. If I go ahead and I’m going to just go ahead and actually go back, clear the screen and do not I’m just going to do LS here. Excellent. So now we have the home directory. The home directory is a place where all the users have their own home directories, where they store their own files and so on. Right next to it you have lib 64 and if you take a look down below there is actually lib. So you have lib 64 for 64 bit systems. Here you would generally store libraries, libraries that are to be used, that are linked and they would be stored either in this folder, lib 64 or just lib.

Keep in mind that they can also be stored here within this folder there’s like Usrlocal libraries, something of a kind. Don’t hold my word for it. I will show you in a moment. There you can also find local and shared libraries but we’re going to get to that in a moment. From here we have MNT. What is a directory MNT? Well, MNT is a mount point for devices. So if you mount a disk or something of a kind, it doesn’t need to I mean, I’m not generally talking about a USB disk that you would plug in with a USB or something of a kind in the MNT folder. That’s the temporary mounting place for drives in general and devices and drives in general. You would be able to mount a drive, I don’t know, God knows where in the world and basically be able to access it from Linux, no problems. Actually it’s quite easy. There isn’t that much to it. It’s actually just one single line where you use the mount command and then you specify the file system type. So it can be in a Windows NTFS in Linux there is a wide variety of them, usually extra four. But we have used XFS here. You would need to specify that and then you would mount it. And if we go into MNT it should be empty.

Not sure, I don’t think I have mounted up anything. Yes, there we go. It is completely empty. However, if you were to mount something you would have a link here. Well, you would have a file here, basically where you could go and access that device, browse its file system as long as you have the support for it. By support I mean that your computer supports the format of the format of the disk. So as I said, it could be NTFS for Windows or XFS or ext four, ext three. It could be xfat or whatever. Xfat is also one of the files. It’s pretty much like XT four. You would use Fat 32 or xfat on your USB flash drives or something of a kind. Let’s go ahead and clear this. Let’s actually go back to LS once more. Right next to the MNT you have a file proc you have a directory proc and within the directory Proclus you have the kernel that is being monitored and where the information is being written. So within this again virtual directory such information is written.

And here Linux truly sticks to the dogma. Everything is a file. So you got this one for IO input output, mem interrupts for threads, if I’m not mistaken, drivers, etc. To all these files are accessible to you and you can monitor them. Sometimes they are used for troubleshooting, but I mean, not sometimes they are used for troubleshooting as well. If I do a less again and we continue on now I’m going to go ahead and skip SRV for now. There is a DMP. That’s where the temporary folders go. And VAR is quite important to you. VAR is extremely important to you. That is where most of the web servers are located, actually where most of the websites are located, not web servers.

So let’s say you made a web server, you brought it up and if I go ahead and type in Cdvar www dot press center. Oh, no such bar. Okay, I didn’t actually create anything of a kind here, but it doesn’t really matter if I go into VAR alone and I do LS I have access to the log files from here, that’s one thing. But also there would be a folder here called www where you would store your websites. Any sort of websites could be stored there pretty much. And anybody accessing them from outside would actually access them from this folder on the net. By typing in the IP address, apache would know in which folder to look for your website. Also, if we go into VAR, basically this is variables.

So if we go into log variables. So if we go into come on, where am I? Pwdr. I do not believe that I can access everything from my regular user, but it doesn’t really matter. I just want to show you that the log files do exist and where they actually are. So for current events in the system, you can take a look at the messages and you see you have several dates. Some of them have been packed down below. Let’s see, what else do we got? We got samba, we got some things that we can recognize cure cups, cron jobs, et cetera. I will go through some of these things in great detail with you. But the most obvious thing that you will be able to understand what it actually is, is Vbox guest editions log. I’m not sure if it’s going to allow me to take a look at it. We could check with the Ll command to see who owns the file, but let’s just see if we can actually do it. We can. Excellent. So here you see, you can read the log file for VirtualBox guest editions and obviously they have failed in my case.

But my main objective was to only get a full screen and that is what I got. There are some other things that the guest editions can be used for or are used for, but I don’t really need that at this point of time. Now I’m going to leave this, go back a step, one more step back to LS again. Down below. We have boot. Boot pretty much contains everything that the system needs to boot all the files needed to boot the system. You can have a look here and there are a lot of things. This is the place from where the Linux kernel is loaded up. Let’s go back. Excellent. So Etsy is something where you will spend a good amount of your days in life if you become a network administrator, linux network administrator. Etsy is a place where most programs hold their configuration files, where you will go to change things, to reconfigure them, to configure them, to take important information out.

And usually a large amount of your troubleshooting will involve doing some sort of changes in the Etsy. Again, we have just Libs and then we have Media. Media is a mounting point for mounting temporary file systems. By temporary file systems I’m referring to, they’re not temporary file systems. That would be a complete error on my behalf. They’re just temporary devices that you would plug in and then plug out. No big deal. It’s like plugging in a USB drive or a hard disk via USB or something of a kind. That’s basically media opt is basically a place where people tend to I mean, the system tends to install some sort of additional optional software, whichever way you want to put it. Root is a home directory of the root user. Now all the other users have their home directory within the main home directory and usually it has the same name as their username.

But for security reasons and for the sake of logic, sake of operational logic of Linux, root home folder has been placed outside of home. Right next to Root we have S bin. Those are the system binaries. And if I mentioned that this one here is actually system binaries. Well, yeah, technically you do use them, but over here you really have those system binaries. Let me just show you for a second. On some systems, for example, SBIN and bin differ by the fact that Fdisc not available. Or if config to see if your IP address see the network configuration is not available. So certain things would be certain commands, certain programs would be placed into SBIN and some other things would be placed into Bin. As I said, one of the most typical examples are Fdisc. And if config on this particular system, you can actually do if configuration from the command line without any problems as pretty much any user unless forbidden to do so. There you go. We have IP tables for a firewall here. We have IV for playing around with your wireless adapter and so on and so forth.

Most of these things would actually I’m not sure if most of these things would require root permissions, if not all of them, who have yum again, et cetera. Let’s just leave this the way that this is actually referred to as system binaries, and this is just binaries, even though you can actually find I did make a bit of an error at the beginning. These are not system binaries. The first one, these are just binaries. And down below you have system binaries. There are differences. For example, some commands could be some programs could only be in system binaries while not being in binaries. As I mentioned before, Fdisc and I have configured the most common examples, although not in red hat. Right next to it you have U as well. Actually, right next to it, we’ll just skip the sys as well. So we’ve just skipped two SRV and CIS. We’ll explain them shortly. But I wanted to explain the ones that are straight off there, the ones that you should really know, USR. Contrary to common belief, this does not stand for user or anything of a kind. Stands something like Unix system resources.

Yes. Unix system resources. If I am mistaken there, feel free to hang me or something of a kind. Scream at me in the discussion section. I will be more than happy to help anyone out. So unix system resources. There you can find all sorts of things. As the name says, it’s Unix system resources. Whatever is needed can be pulled from there as a resource. Whatever resources are needed can be pulled from USR. You have their local libraries, shared libraries. But let’s go ahead and dive into the USR and see what awaits us there. You see, you have been you have Etsy for configuration files. You have Lib and Lib 64 local spin share sort, SRC and TMP as well. I don’t know. USR is like a file system to itself. To me anyway. Don’t go on to a test saying this or something of a kind. That’s just what it appears to be to me. The last two remaining are SRV, where service data is basically located.

And down below we have Sys, where data is exported from the kernel about all sorts of subsystems associated hardware and device drivers. Anyway, over here, during the course of this tutorial actually, you have managed to see what the Unix or Linux like file system is in general. How is its design, how is it made? Well, not how is it made, but what it was made to resemble. What sort of an idea is behind it. It’s a hierarchical state. You have the root folder in it. You have these sort of folders, and below them they just keep on branching, unlike the window systems where you have different partitions. And for example, the root would be C, and then you would go there into System 32 and there you would have all those system files. Unlike here, where you have SBIN and Bin and you have the library.

So it doesn’t matter how many disks you have on your computer, you would have literally hundreds of them, or just one. And this file system would be the same as you see it before me. Now, depending on what sort of information would you be browsing, you would be going from one disk to another. But for example, you could have different home directories on different disks. And that is nothing strange that would function. No problems. In any case, I would like to bid you all farewell. I sincerely hope that I shall see you in my next tutorial. But above all, I wish to I wish you a tumble to luck, because you’re going to need it. And for anything else, just feel free to go up in the discussions and ask whatever you wish.

2. Hard and soft links in the Linux file system

Welcome all to this tutorial. Today I am going to be talking about hard and soft links. They are directly connected to the Linux file system or related to that subject. That is what I meant to say. I’ve already shown you how you can spot links with an LS command. Basically you would need to type in LSLA or just L and here it says it’s a directory. So D stands for directory and Hyphen stands for a file. And instead of an aside from a hyphen and a D you also have an L which stands for a link. There are two types of links on Linux file system you have hard and soft links. Now they differ to a very large extent and they’re basically a hard link would be just a different name for file. So imagine you have a file that is stored on your hard drive and you have simply given it different names on multiple locations so that it would be accessible or that you would prevent its accidental deletion or something of a kind.

It doesn’t really matter. I just wanted to understand the concept of a hard link just different names for exactly the same file and those hard links can be placed pretty much anywhere. Now soft links you have a file on your hard drive and then you have links to that file. I know it can be a bit confusing but think of it this way if you had a bunch of soft links and if you deleted the original you could no longer access the file that is on your hard drive because it would be gone. If you have several hard links and if you delete any number of them as long as one still remains you should be able to access that file without greater difficulty. Even though you’ve deleted some of them or most of them you can still access the file. As I said hard links are the same files, just different names and possibly in different locations while soft links are just in effect links they guide you through it, they give you a path.

They are not the files themselves to which they provide links. Anyway, let’s go ahead and see how do you actually create a soft link? We’ll take a what shall we take? Well we won’t take anything. We’ll actually create something touch soft L and now we’re going to go ahead and say echo I am here and you are there and this is a completely wrong syntax.

Okay but let’s attend the file soft L. There we go. And if we do Ll space soft L you will see that there is this markation here aside from everything else. Let’s clear the screen actually just to get a better overview. Excellent. So it says that it is a file and it says one meaning that there is only one of there is only one link that’s soft L which is a hard link. Well that was a poor expression on my behalf. It’s not a hard link, it is a file itself. But here where it says one, that only means that it has one link. Anyway, if we do Lnspace S, and if we do Soft L and we’re going to give it a link to Soft, and if we do ll again Grep Shisoft, we shall see that one of these is a link and the other one is an actual file. The first one is a link. You see how it is written out, how it is displayed here. Quite simple, quite fair. Again, we only have one link because this is a soft link.

So it doesn’t actually count it here. But if we oh by the way, you don’t need to be root to be doing this. I was root because I was testing something out and I just stayed that way. Doesn’t really matter now for the sake of this demonstration and if we do Ln, Soft L, and if we give it hard link Soft, if we do the command again, we’re going to have a look and we’re going to see that this number has indeed increased the two. So the file has now two links. The soft link doesn’t really count. We are not really counting that. But you see here, it doesn’t say that it’s actually a link because it’s a hard link. Basically it’s just another name for exactly the same file. It can get a bit confusing. Even I get confused here somewhere. If I have made an error, forgive me, please point it out. Just so you know, I do really encourage that any sort of criticism is of course welcome and it does help me improve. But for the time being, understand that hard links, once again, there are just different names for the files.

There we go up here they’re just different names for the files and soft links. They are the actual links to the file. They do not contain the file itself. Let’s go ahead and see what happens if we try to open up. So cat link soft, there you go. I am here and you are there. We are indeed able to access the file through this link. And if we go ahead and remove the Softelp now, what happens is that we will not be able to access it via the Soft link. It says no such file or directory because it contains a path to that file, a link to that file and that file no longer exists. But look at this, if we do cat hard, even though the original is gone, the original name of the file is gone. Hey, guess what? It’s going to be able to print out I am here and you are there. It still has access to the contents.

I hope that I have managed to clarify this subject, at least to a certain extent. Creating links is important, understanding them to the forest of extent, maybe not so important for the Red Hat exam, but it is important for you as a system administrator in general because you will be encountering these sort of things. Questions are welcome. I expect them. It’s a bit confusing, I know. Just go ahead and ask away anything you feel like asking, and I will be more than happy to try to answer any of or questions in regard to this subject and pretty much anything else here on Udemy. Until next time. I’m going to bid you farewell and wish you a ton load of luck.

3. Backups, recovery, and compression in Linux part 1. Introduction and use

Welcome all to this tutorial. Today I am going to start talking about backups and recovery. Also in addition to this we will talk about compression as well. These things go hand in hand with one another and they combine rather well. First off, you as a system administrator, I mean you will absolutely need to perform warm backups and recover information from those backups. This is one of your most frequent tasks that you will need to do and performing backups and Linux is not that hard. It’s actually quite easy, there isn’t that much to it. The trick is figuring out what to back up as there can be quite a lot of it. And usually what people do is they schedule automated tasks which perform backups on either daily, weekly, monthly basis or every so hours or something of a kind. When that backup happens, the old one gets overwritten and lost in such a way they manage to preserve space. All of this we will do throughout this chapter but for the time being I just want to show you some basic functionalities of Tar which you will need in order to create a backup.

And before that I have as previously for Vim created a small file for myself and I want to show you one command that you can utilize in order to monitor the status of a file. Namely, this is mainly used for the monitoring of log files. The command is tail. So if I type in Tail and if I type in Tartext, which is my file and press Enter, what did I get? Pretty much the same thing that I would get if I was to write cat. However, tail does come with a very neat functionality and if you pass a F argument and press Enter, you will see that the prompt is standing by and waiting. It is monitoring for changes to occur within a file. Let’s go ahead and enact some changes and see what happens. Type in Echo and let’s type in something here I have changed you. Let’s give it an exclamation mark as well. And if you remember from the previous tutorials greater than greater than sign means append. So we are pending the contents of this file and the file name is Star. I am currently in the directory where the file is located but I could have just as easily written here file sorry, path to the file and then typed in Tar text. But at the moment I am working in the same directory so it is completely unnecessary.

I can just write the name of the file like this and save myself a bit of typing. Now watch what happens in the upper terminal when I append this file. Event not found exclamation mark posing a problem hold on did I mess it up? This was for my test runs. Okay, let’s try did I mess it up? And you see immediately up there it is shown but I also want to make this thing work with. I have changed you. It is vital to me. I have no idea why, but okay, we’re going to try an escape chart and see how that works out. Event not found. Why aren’t you memorizing it? There’s something fundamentally wrong with this command, and I am going to find out what it is. So it is the exclamation mark. Let’s type in escape, and we’re going to tell Echo to use escaped characters. There we go. No, that’s not what I meant. Don’t do this to me. Okay, we’re not going to give up. We’re not going to give up. We’re going to be using Echo help. Space. What do we need? Grip. And then we’re going to go ahead and type in escape. Nothing pops. Okay? Oh, right. You cannot use this with Echo. Terribly sorry.

Man echo grep ESC. Not a bad way to actually pull the information from the man pages. A lot of people don’t actually know this, but you can also grab things from the man pages. When you issue a man command for anything that you want, you can use Grab to figure out what is where. Press Enter. And there we go. It is E enable interpretation of backslashes escapes. E disable interpretation. Okay, that’s by default. And e. I suppose that’s for escape. Strange that it couldn’t be stranger. I love it when things like this happen to me. I’m like a magnet for problems. It is amazing. Now let’s give it these, and I’m going to go ahead like this. Event not found. I hate you so badly. Let’s try it the other way around. Event not found. Because it’s escaping. I have honestly no idea why the exclamation mark won’t work here. I’m going to go ahead and check that out for you in the follow up tutorial. But this is quite interesting. It has intrigued my imagination here. I’m going to go ahead and figure it out in the next tutorial why it hasn’t actually worked out and why you cannot put an exclamation mark at the end. And I suspect it’s going to be something interesting. But in any case, I have shown you how Tale works. This is very important for you. It’s going to help you out a ton, especially when monitoring log files. You will type in tail, then space, F, space, tartext. Well, so not tartext. You will obviously use your own file. You can specify a path file to any file that you want. As long as you have the permissions to actually pull the information out of it, you’re good to go. Also, another bad thing is when you’re starting up a program, you see that something is wrong that it doesn’t want to start. It’s not giving you any errors. It can be problematic.

You go into the log files in VAR log, and there you find the appropriate log for that particular program. Usually it should be messages or something of a kind and then type in tail f type messages here most likely, and then see what happens in the moment when you start the program. Just have a look at the message and then if you can actually figure it, if you can get that message there, then you can go online on the net or you can even solve it yourself, you just get the error message from there. Anyway, let’s go ahead and close the stop monitoring of the file.

And the universal pretty much interrupt for Unix Linux like systems is Control. I know it can be a bit annoying, primarily because Control V and CTRL C do not work in the terminal as they work everywhere else as copy and paste rather instead control C works as an interrupt. So now that we have that out of the way, let us go ahead and examine this Tar file. Maximize the screen, delete the F because we don’t need the live monitoring now I have the file modified, but guess what? We can combine what we have learned from the previous tutorial.

So just type in clear and then cat m tar texture one and there we go. We indeed have only that part from the file. What I’ve just written this command. You should know what it does and what it means by this point of time. I have explained it in great detail in the previous tutorials. Anyway, let’s go ahead and focus on the Tar. Finally, after long last. So you would type in Tar and then space, then minus sign or Hyphen, however you wish to call it. The first argument C that instructs the Tar to create or override the exist if to create a file. If it doesn’t exist, if it exists, overwrite it or yeah, just write over it, I don’t care. I do care, but that’s just what you are telling to the computer. If it exists, overwrite it. Next we have V.

And what have we learned that V represents? Well, verbosity verbose output. You want the computer to be telling you what to do. Although with a lot of backups, since a lot of them are automated tasks, it’s probably a good idea to omit the V just to omit it completely and not have it here. Unless you’re doing the manual backup, then you want the V there to actually see what is going on. But if you have a scheduled task that the machine does that you will not see and most likely you will not even be physically present there when the backup happens. There is no need to waste resources of the system. You’re not wasting a lot, you’re wasting a very small portion.

But it doesn’t matter. It pays to be efficient in every situation. Next up we have P. P is used to preserve the permissions on files so you don’t have to mess around with it. Again, we have learned what permissions are and there’s the three sets of permissions for users, groups and world. Why is this important? Why would you want to preserve the permission file structure? Well, file hierarchy. Well, imagine the following scenario. You are basically performing a backup of a website and you want to backup the entire site with all the file structure, the whole file structure, everything that is in there. Now I don’t know, there could be like 500,000 folders, files, whatever in there.

And imagine if you just compress them and unpack them somewhere and you don’t have the permissions set up the way they were set up there. What are you going to do? I mean you’ve just restored a backup and now on top of that, you have to go through every single file and adjust the permissions there once again to match. The original permissions provides of course, that you have the original file somewhere, which would be ridiculous, I mean it would take a ridiculous amount of time. And as you would do this, the chances of you making an error and making your server unsecure by giving a right permission somewhere to some file or execute permission to a wrong file are astronomical. Basically, if there are enough files there, if you need to change like 1000 files, your chances of making an error are practically 100%. That is why we have the key option to preserve these things.

All that you need to do after you have preserved the permissions within a backup file, once you restore it, you just copy it to a folder where you want it and that’s it. The permissions are the same. You don’t need to do anything more to it, which is fantastic. Next up, we want to compress it. Now, strictly speaking, this argument is not meant, this is not one of those mandatory arguments. Neither is key of course, but it is useful. We are telling Tard that we want the file compressed so we want smaller file size, which is of extreme importance. And as I said, it always pays to be efficient. You don’t have to compress it of course, but there is no reason why you shouldn’t. You’re saving disk space. I know that a lot of people say that it’s cheap and that it’s free or something of a kind, but most of those people generally don’t do anything serious that requires large amounts of space on your drives.

Sure, two, three terabytes are relatively cheap, but try getting 100 or something of a kind and see what happens. Especially if you’re making backups of your databases, of websites and if you are continuously doing this of a large, large, large database, you can’t make two backups. You literally have to make one and then the one that you made previously has to be overwritten by the new one because you don’t have enough space. It’s impossible. Or you have another option of buying a ton of load of more storage which in turns costs money to buy and costs money to maintain. And so on and so forth. That is why you should always compress. There is no reason not to. You won’t break your files. I know, as I stated previously, I do believe that I have anyway, that in Windows things can go pretty badly when you compress things. I don’t know, you can have problems with files.

They can get broken, corrupt. Well, not broken, but the files can get corrupt or something of a kind. That does not happen in Linux. To say that doesn’t happen at all would be improper of me, but 99% of the time it won’t happen. So there is no reason why you shouldn’t do it. Anyway. The next argument is F simply allows the tar to create a new file on the file system. And now I have written out here for myself two things that you can write here. So this one you do need to write. This is the file where it’s going to get compressed. So this is what you are compressing it to and this is what you are backing up. So destination, destination of what you want to back up. Perhaps I should have renamed them like backing up file and File, sorry, destination would be File that gets backed up and File tar GZ would be the file where the backup will be stored. You don’t necessarily need to give both of these here. You can only give one, the first one, file tar GZ.

But that will mean that it will take your current working directory and it will back that up. That is not what we want to do here. What we want to do here is, I don’t know, we can back some silly things. I will show you which ones shall we back up? But for the time being, let us first type in the path where we are going to perform the backup. Notice that you can also use here, shortcuts for paths. They’re pretty much universal, I can use them anywhere. And let’s type in Backup tar GZ, tar GZ, my fabulous typing. And now we’re going to go ahead and type in Tilda once again. Sure, why not? Let’s back up the contents of our home directory into our home directory, which generally isn’t a practice. You perform backups into another fold, you would store backups into another folder. You would either have a dedicated disk or a dedicated space in the server or something of a kind. But it really doesn’t matter. I could have specified pretty much any path here and it would back it up to that location as well. Provided of course that I do have the permissions to write on that location.

So let’s go ahead and press Enter. There you go. You see that everything is being backed up quite literally. And there seems to be a lot of things in my home folder of this user home random guy file changed as we read it. Excellent.

So let’s go ahead and type in LS. There we go. We have backup. Tar GZ. We have successfully backed up pretty much everything that was within this folder. Notice that we didn’t only back up what was directly within the folder, rather instead we have there we go. So it has went into the home folder of the user. It has picked up this folder here, and then it went into that one. And then it copied this, and then it backed up this, and then it went into this folder, and then it backed up the contents of that folder. So it is recursive.

It just goes jumping and jumping and jumping. If you’re wondering that we why don’t we have these dot PKI folders or these dot macro media folders generally, the dot folders, the folders that begin with a dot. Well, we do, they’re just hidden. We haven’t listed them. You can use LS. A. And there you go, you can see them. Let me just clear this up for you so you can see a little bit better. You can use Space A to list all and there you go. You can see pretty much everything that we have that we have backed up in the Tarball. Anyway, I do all farewell and we shall see each other in the next tutorial, hopefully.

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