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The "What is Linux" Lesson is part of the full, Complete Intro to Linux and the Command-Line course featured in this preview video. Here's what you'd learn in this lesson:

Brian explains that Linus Torvalds created Linux using the Unix codebase and made Linux free and open source, gives a high level overview of the Linux Kernel, and explains the difference between Linux and Linux distros.

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Transcript from the "What is Linux" Lesson

>> So getting to Linux, Linux isn't directly Unix, it's not like you have the Unix codebase, they took that and they made that Linux. What happened with Linux is this guy, Linus Torvalds like sat in a room and basically created his own version of Unix, and he tried to be compatible where it made sense but he also branched off in his own directions when he wanted to.

[00:00:21] Cuz at the time there was no free and open source version of Unix that he was satisfied with and that's because BSD was not out yet at that point. BSD by the way, I think stands for Berkeley Software Distribution, yeah, Berkeley Software Distribution. I learned that when I was researching for this course.

[00:00:40] So yeah, Linus was unsatisfied with the free offerings. BSD didn't exist when he started, but it did exist by the time that he finished Linux. Yeah, and something I found interesting about Linux is actually he didn't want to call it Linux cuz they thought it would be too considered to name something after himself.

[00:01:00] So they went through a couple names before they actually landed on Linux. Actually, I don't even think it was someone else. It was someone else that actually said no, you're gonna call Linux and that that's what actually ended up sticking. So suffice to say, Linux is extremely important to modern computing.

[00:01:17] As of the writing of this course, all top 500 supercomputers run on Linux and that's a relatively recent change that there were some that ran on different operating systems, but as of today, all top 500 run on Linux. Much of the mobile phone market shares on Linux which is Android, which is a Linux derivative.

[00:01:34] And pretty much almost all of the websites that you know and love are running on Linux. Some of them are running on Windows but many of them are running on Linux. Me personally like all of my servers that I ever do for for work has always been on Linux for my entire career.

[00:01:54] So, why would you choose Linux over something like say like Windows which is obviously I work at Microsoft, I think it's a fine operating system. I have my Windows computer right here. Probably slightly off of frame for that you can see but I use Windows quite a bit as well.

[00:02:08] But why do people continue to choose Linux over other things they could choose? Well, the first thing that's probably important to a lot of companies and probably many of you is that it's free. It's free. It's open source. It's online. You never ever have to pay there's no one to pay for it right?

[00:02:26] So that's important for college students that need an operating system. But it's also important for like really big companies that have tens of thousands of servers. That's millions and millions of dollars of licensing that they don't have to pay. It's very well maintained because it's so widespread. There's just a ton of eyes looking at it and there's multiple companies that their entire thing, their entire reason of being is to work on Linux like Redhat and Canonical.

[00:02:54] And so there's a lot of really smart people working at Linux at any given time. So it's very well maintained. If you have like real bugs, people are going to find them. You can report them and you yourself can contribute, if Linux doesn't do something that you need it to do, you are also welcome to hop into the mailing list and contribute.

[00:03:12] It runs just about anywhere. It runs on Intel processors. It runs on AMD. It runs on ARM, it runs of Internet of Things. It runs on phones, fridges, cars. If it has a processor in it, chances are you can probably run Linux on it. Well, chances are it's probably already running the Linux.

[00:03:31] I know of Teslas, for example, and Audis run Linux on the car, so it's everywhere. Most of the things you need for it already exist. Being around from the 70s and so many people using it means that if you have a problem, chances are someone else already had your problem and solved it.

[00:03:52] So there's a great ecosystem around it. And just the knowledge base for Linux is enormous, right? It's a huge business. So if you know Linux there's a good chance you can get a job doing Linux and if you need to hire someone, chances are, there's many experts out there that are waiting to be hired for it.

[00:04:14] So that's kind of the ecosystem reasons. It's also just technically predictable, I think, and stable. And I think that really inspires a lot of confidence in a lot of people. So we're gonna talk about all of these things I'm just kidding. I don't know anything about anything that I'm showing on the screen right now.

[00:04:35] But I want to show you like this is actually the disparate pieces of what makes Linux, Linux. So this is actually the kernel which is kind of the core part of Linux. And this is kind of what goes into the kernel and how it relates to each other.

[00:04:50] Again, I don't really know anything about this, but I wanted to show you that it can be distilled down to a graphic anyway. And again, I got this from Wikipedia you can see down here here's the citation. But I wanted to get to what makes something a Linux and what makes something a distribution, because for me until I researched it, it actually was kinda unclear to me as why is Ubuntu different from RedHat.

[00:05:17] Why are those two separate things? What do they share? What makes Linux, Linux? And the answer to that question is they all share the same microkernel, which is like the central part that does all of these things, right? So it handles memory, it handles scheduling, it handles processes, it handles the file system, all that stuff is part of the kernel.

[00:05:37] So all of Redhat and Ubuntu and Debian and Mint, those are all sharing that kernel, and then they're building stuff around it, right? And that's what you'd call a distribution or often they're just called distros, right? And there are so so so many distros, right? There's one Linux kernel, but there's a billion different distributions of Linux.

[00:06:00] And they all kind of specialise in different things. In this class, we're going to be going over Ubuntu, which is just the one that I've used the most and probably the most common, so it's probably the most useful for you to learn on. But I'm by no means asserting this is the only one that you should use or anything like that.

[00:06:16] I'm pretty sure there's someone in the chat that fight me that Arch is like the best thing ever and that we should all be using Kali Linux and then Mint on our phones and I don't know, there's just so many different distributions. But these distributions they'll add software on top of the kernel so they'll have like different desktop experiences they'll have different programs, they'll have different package managers, they'll have different networking capabilities, right?

[00:06:41] They kind of take those microkernel abilities and they expand that out into a full operating system. So hopefully that kind of demystifies a little bit like what's the difference between what makes something Linux and what a distribution is. The one thing I did want to call about Ubuntu is it's a downstream distribution of another distribution called Debian.

[00:07:01] So Debian has been around forever, and it's one of the more popular Linux distributions. I actually still use it quite a bit. Like if you download the Node.js container off of Docker Hub, it's actually deviant image which I found very interesting. So Ubuntu kind of took Debian and polish it up and made it like the user experience a little bit nicer.

[00:07:25] Ubuntu is backed by a company called Canonical and they're a great company. And so that's kind of why I choose Ubuntu over Debian. And there's actually even a downstream from Ubuntu called Mint as well. So if you want to even go further down the line that's possible as well.

[00:07:42] Ubuntu is just a good one to learn because it's very flexible in all of its applications, it can apply to internet of things, it can literally be like your desktop computer's operating system, it can run servers. It's all over the place. So that's a good reason to learn Ubuntu is it's flexible and all the things that it can do.

[00:08:01] But I'm going to just toss down here at the bottom you can see I threw a couple more that I have used and I think are pretty good. One being Debian, Mint is another one that's based on Ubuntu. RedHat that's another like very enterprisey like large scale server.

[00:08:16] It's actually owned by IBM now. Alpine I use quite a bit. Alpine is for making very minimal containers. And we're not gonna be talking at all about containers today, but there's another great Frontend Masters course on containers by this guy. [LAUGH] So if you want to learn about containers that's out there as well.

[00:08:36] Kali, there's Arch is another one that didn't have on here, CentOS like there's a bunch of stuff that you can get into as well. So that's kind of the history of like what is Linux? Yeah.
>> Is the question about what is downstream?
>> That's a good question.

[00:08:54] So when I'm saying downstream. So there's a distribution of Linux called Debian, right? There's a open source community that maintains Debian and that's the lowest level or lowest level is not the correct term for that. So Debian is like the mother distribution here, right? And then they take Debian, and they add more code on top of it that makes it a downstream distribution, right.

[00:09:22] So there's Debian and then they build stuff on top of it and that makes it Ubuntu. And then they build stuff on top of that and it makes it Mint, right? So they're taking a base distribution that someone else has made or a whole community has made and they're adding stuff around it, that's what downstream means.

[00:09:37] So, Ubuntu is downstream from Debian, in that respect. Clear as mud? Probably.