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A big part of being a developer is being able to use the terminal or the command line.

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Well, what is it? In this video we're going to tackle this question and teach you a couple of very useful

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commands.

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Now on a Mac you simply do command space (CMD-Space) and type in 'Terminal'.

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Press 'Enter' and then the terminal will open for you.

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It's one of your applications and it's on every computer.

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If you're on a Windows machine then it is the command prompt and I'll leave instructions at the end

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of this video of how you can access them but you might remember this from the Traceroutes video earlier on

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in the course.

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But what is it? Well, it's how humans originally communicated with computers up until the 1980s.

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It was the main way humans gave instructions to computers and computers gave output to the humans.

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We didn't have something called the GUI or the Graphical User Interface such as me opening up a new

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folder and changing the name of this folder or opening up Google Chrome.

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I don't really need to know how this is done behind the scenes.

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I just click on an icon and it opens it up magically for me.

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But command lines are really useful because you can do the exact same thing that you do visually on

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a Graphical User Interface like I have here on the command line but they tend to be much much faster

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to do as I'm going to show you in this video.

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And there are also common ways to access different computers around the world, like if you need to access

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a server in another country where your web app is hosted.

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Well you'd use the command line and I'll show you how to do that later on in the course.

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Now in your day to day job you'll be using the terminal a lot because you'll have to access servers

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the database your front-end application.

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But you can do all of that in one from the terminal.

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You can also download scripts that other people have written from the internet so you can use in your

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project.

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Now these are all things I'm going to show you in the later sections.

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The commands that I'm about to show you work on a Mac or Linux. For Windows,

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I'll have the Windows version command at the bottom of the video as we progress,

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most of them are the same but there are a few differences.

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So let's get started.

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The first command I'm going to show you is the 'ls' command.

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I simply type in and press enter and it lists everything that is in my current directory. 

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What is my current directory?

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Well, I do 'pwd' for Present Working Directory and I see that I'm in the '/Users/'          , that's my user name,

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so I'm in my username folder and these are all the things available to me.

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If I do 'cd' then I can go into this. If I wanted to go to, let's say, desktop,

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I do 'cd Desktop'.

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And now if I do 'ls', I see that I have 'untitled folder', because that's the only thing on my desktop right

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now.

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I can also do 'cd ..'

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and this brings me back to one directory up.

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I can also do 'clear' to clear up my terminal and have a nice fresh slate. There's a short command 'cd /'

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and this takes me to the root directory.

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If I do 'ls', I see that I have 'Applications, Library, System, Users..'

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That's the root directory of my Mac, essentially my Macintosh HD.

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I can also do 'cd ~' and this takes me to the user directory.

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Let's clear this again.

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And if we check where we are.

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All right, let's change this 'untitled folder' to something like 'test', okay?

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Let's say I'm in the user directory right now, I want to access 'Desktop' and then the 'test' folder.

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I would simply do 'cd Desktop/' and then 'test'. And now I'm in the 'test' folder, but there's nothing

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in there.

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So one thing we can do is I can say 'open .' and it opens a folder that we're currently in. Okay, we're

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in the 'test' folder.

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Now if I just put this to the side over here so you can see, I can say 'mkdir(make directory)', which is make a

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folder 'name'. So 'name' here will be whatever I want the folder to be titled. Let's just say this folder

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would be called 'webapp'.

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Did you see that?

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Now 'webapp' shows up in my folder. Let's change the view here so you can see it better.

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There you go.

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If I do 'ls' now, I see that we have the 'webapp' folder and as we know, we can go into it. Let's double

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click here to see what we have.

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We have absolutely nothing.

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Well, We can create a file in here by saying 'touch' and the name of the file.

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So let's just do 'index.html'.

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There you go,

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'index.html'

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Now what if we wanted to open this 'index.html' again, we just do 'open' and the '.(dot)' means we open

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the folder we're currently in which is here.

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But if I do 'open index.html', it opens the file for us.

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How cool is that?

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But 'index.html' is pretty empty right now.

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Wouldn't it be nice if we could open Sublime Text from here and add something? Again, you can do that with 'open'.

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You put in 'a', so '-a' for application and the name of the application, so 'Sublime Text'. Close the double

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quotes, press enter, and look at that.

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I have Sublime Text. But if we wanted to do,

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'-a(application) Sublime Text' and open the 'index.html' file. We just do this.

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And now I can say 'html', and it will just say 'Helloooo world!'

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Save that.

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And if I do 'open index.html',

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We have our 'index.html' file loaded.

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Wasn't that a lot faster than right clicking, creating a folder, then dragging everything to Sublime Text.

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And as you can see, you can do things really really faster.

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OK, let's change something.

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Let's - I'm going to close Google Chrome and Sublime, and in the 'webapp', let's say I wanted to change the name

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of 'index.html' to 'about.html'.

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Well, I'll do the 'mv' command, which stands for 'move',

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but it just moves 'the index.html' file to 'about.html'.

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So it's a little trick -

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You're essentially just moving one file to another but, by changing the name, you create a new file and

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you replace it with the old one.

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So now I have 'about.html'.

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Very cool.

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Now these commands typing them can get pretty tiring.

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I can press the up arrow and it goes through my entire history, which is very cool. I can also press the tab

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key and it will bring up my most recent commands or completes what I'm about to write so you can do it

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really really fast.

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And when your commands get longer and longer it's a very useful thing to do.

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OK.

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I don't really need the 'about.html' file anymore.

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Let's remove it.

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We do 'rm', for 'remove', and the name of the file 'about.html'.

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It's been removed.

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Perfect.

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Now, what about the 'webapp' file, we can remove that as well.

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But if I just do 'rm webapp',

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well, it's not going to work.

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First of all if I do 'ls' or 'pwd(present working directory)', I'm in the 'webapp' folder.

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So I need to move back to the 'test' folder.

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Let's clear here.

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Do 'cd'.

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Now, my 'pwd(present working directory)' is - I'm in the 'test' - so I can remove 'webapp' by doing 'rm webapp'. 

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But 'rm' only works for files. To remove a directory or folder,

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You need to do 'rm' and then use the '-r' option

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and then the folder name, in our case's the 'webapp'.

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There you go, it's gone.

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And with that, you know what, we can remove the 'test' folder as well.

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We can go back to our 'Desktop' and then do 'rm -r test'.

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There you go, it's gone.

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And one last trick on a Mac.

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You can do this.

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Right?

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Very very cool.

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As you can see, you can have a lot of power with the terminal. And I want you to get used to writing commands

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on here. And from now on, try creating files and folders this way.

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Eventually you'll get more and more comfortable with it and things will be much faster than

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just using the GUI. In the developer environment section,

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I'll show you how you can change this boring black and white terminal to something like this.

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That's it for now.

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See you in the next video.

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Bye-bye