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All right, guys. In this module, I'm going to teach you something really, really cool and really useful
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as well, not just in iOS development, but in your future life as a developer for any other technology,
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web development, or back end development. The command line is going to be your friend.
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So let us introduce you to your friend.
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So in order to use the command line on a Mac, we will be using the Terminal application. And the Terminal
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is a way of accessing something called the Bash Shell.
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So when you're a beginner and you're getting to grips with the command line, there's a whole load of
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new words that you will come across. And I'm going to try and debunk some of the most common ones you'll
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come across.
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So what does the Bash Shell?
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Well, to understand the Bash Shell, we first have to know what a shell is.
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And this graphic is a good way of tackling that.
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So if you think about your operating system as a pistachio nut, then the kernels, so the actual pistachio,
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the thing that you're going to eat.
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I'm really sorry about all the food analogies.
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You can clearly tell I'm pretty much hungry most of the time when I'm recording these videos.
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But let's get back to the topic.
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So if your operating system macOS is a pistachio, then the actual nut is the kernel. And in computing,
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the kernel refers to the actual program that interfaces with the hardware.
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So it's the core of your operating system.
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Now, the shell of your pistachio or the shell in computing refers to the user interface for you as a
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human to be able to interact with the kernel, and in turn with the hardware of your computer.
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And there's two variants to the shell,
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there are graphical user interface shells.
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So, for example, when you open up Finder, you're using a graphical user interface to access and find your
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files.
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But there's also a command-line interface which is what we're going to be talking about and what we're
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going to be learning about in this module.
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So this is an alternative way of interfacing with the kernel.
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Now, it can seem intimidating at first.
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Now, as a beginner, it can seem quite intimidating. But I want to show you that it's actually super simple,
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and once you understand it, you're going to see that it's actually a really, really useful tool at your disposal.
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So coming back to the shell that we're going to be using which is a Bash Shell and it stands for the
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Bourne-again shell, and it's named after a Mr. Bourne, but not this Mr. Bourne, but this Mr. Bourne. And I can
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attest that they are equally badass. And the Bourne-again shell or the Bash Shell is a CLI or a Command
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Line Interpreter for the UNIX system. And you find UNIX-based systems or UNIX-like systems all over the
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place.
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So, for example, Linux is a UNIX-like system and a lot of servers will run on UNIX. and even the Mac that
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you're using right now,
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macOS 10 or the newly named macOS runs on a UNIX-like operating system. And this is a completely different
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family from the Windows side of things which uses DOS and Windows.
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So why is any of this interesting?
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Well, once you're familiar with the Bash Shell, you're going to find the skills that you acquire to be
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useful, not just for installing libraries on macOS, like we did in Clima, but you're going to be able
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to use it in other projects, other cases, other operating systems as well.
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A lot of things that you can do with the command line can be done using the graphical user interface.
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So why use the command line at all? At the end of the day,
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what it all boils down to is about greater control.
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And in your journey of becoming a better developer, you will need to understand and exert more power
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over your tools,
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that is the computer hardware.
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But on a more day to day basis, you will find that if you're a regular command-line user that it's actually
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easier and faster to do a lot of really common things. For example, inside the Terminal if I wanted to
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make a music folder, then it's as simple as mkdir Music.
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And now there it is,
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there's my music folder.
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But if I want to do it inside Finder, for example, I first have to go to Finder,
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I have to navigate to my desktop or whichever directory I want to create it inside, and then I have to maybe
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right-click New Folder, and then type something like Music,
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right?
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And that takes a lot of effort, whereas, you know, say, if I wanted to create Music2, right, make another folder,
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it's as simple as hitting the up arrow and hitting 2.
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So for me, it's a lot about speed and a lot about control.
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The other thing that you notice that is very prevalent with the Mac sort of environment or the Apple
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Ethos is to try and hide a lot of the unnecessary things from the common user.
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So that includes things like files and folders as well.
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For example, by default, your library inside your Mac is actually hidden.
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Now, of course, I haven't
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been able to show students how to navigate to certain places using the graphical user interface. But by default,
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Apple's stance is to make the user interface as simple and avoid confusion as much as possible,
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but it's slightly paternalistic. But with the command line, you have full control and you have a lot of
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flexibility.
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So, for example, right now, let's just delete these two folders that I won't need. 
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On my desktop, you can only see one folder with no files, called App Development, right?
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So I'm on my desktop at the moment inside Finder. But, actually, if you use Terminal, you can actually list
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all the files.
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And if I just add this dash a flag, you would actually see that
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I've also got a folder called SecretStuff, and you can create these hidden folders by simply writing
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mkdir., say, Secrets.
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And now if I list again, I've now got two secret folders. And later on, what we're going to teach you
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Git and version control. We're going to be using the command line really heavily to show you the easiest
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and, probably, the most popular way amongst developers at least of using Git and version control.
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So I hope I've sold you on the virtues of the command line.
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So without further ado, let's get started learning how to use it,
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what are some of the most common commands, and some tips and tricks as well.