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So the first thing you're going to do is open up your Hyper Terminal.
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So the first thing that you might notice is that my preferences or my display or the skin on my terminal
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might look different from yours.
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Now I have it this green on black,
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just because I do a lot of development at night and it helps my eyes and it helps me going to sleep
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afterwards.
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And also there's the added benefit of when you're sitting in Starbucks and doing a lot of Bash scripting,
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people look at you really funny, like you're going to hack into their phone or something.
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And if you really want to take it to the extreme, and you've never seen this web site called hackertyper.com,
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you can actually pull it up on your browser and you can basically just bash the keys
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and you look like you're writing some insane piece of code.
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This is actually part of the Linux kernel, in case anybody's interested,
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and it's written in the C programming language, so that also is something that you can impress your friends.
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Now coming back to our actual lesson let's talk about the first command that we're going to learn today
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which is ls, which stands for list, and this lists all the items inside a particular directory. So you
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can see the location of where you are by whatever shows up after the colon.
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So at the moment this tilde shows me that I’m in my user directory. So that, in the Finder world, is basically
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here.
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So for example if we go back.
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So the root or the highest level in the hierarchy is your Macintosh HD.
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And then the next one is your Users folder.
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And on this computer my user name is angelayu.
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And when you see that tilde sign, you are at this level, you are inside this folder right now.
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So if I wanted to list all the items that are inside that folder then I simply write the ls command and
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hit enter.
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You can see it prints out all of the folders and files.
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So I've only got folders inside my root directory and you can see that it’s exactly the same as what you
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see in Finder.
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Now this is the location that you are taken to by default
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when you open up your terminal.
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This is the starting point.
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Now what if you don't want to be inside this folder?
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What if you want to navigate to a different directory,
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right?
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Say for example if I wanted to go into my Documents, and I want to go into Learn, and I've got this folder
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called Languages.
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And right now I'm learning German and the International Phonetic Alphabet in case anybody's interested.
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So how do I get myself from here all the way inside here?
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Well this is where the change directory, or the cd command, comes in handy.
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So we know that we are here right now because of the tilde sign.
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Let's navigate one level down.
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Let's go into our Documents folder. So I can simply write cd Documents.
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Now I can type out the entire thing myself but as a developer we're always looking for lazier ways of
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doing things and faster ways of doing things.
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So if you start typing Doc and you hit tab you can see that the terminal will auto fill the remainder
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of your folder name.
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Now you need enough letters for it to know what you're talking about.
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So for example if I just wrote Do, then it will tell me that there's Documents and Download.
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Which one do I want?
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So if I add a w and then I hit tab, then it knows that it can only be Downloads for example.
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Okay.
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So let's change directory to Documents, and you can see that the location has changed.
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This directory name after the colon is now saying Documents.
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So that means I am currently inside here. I am at this level.
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So if I wanted to go into this level, I would have to navigate into the Learn folder.
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So if you're following along, what would you type?
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Give it a go.
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Similar as what we did before we’re simply writing cd Learn and hit enter.
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So now we're inside Learn. Now it's a little bit tedious to navigate through directories one by one by
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one,
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right?
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So if we already knew that we want to go all the way into here then we can actually specify the entire
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path to get there.
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So for example right now I'm inside Learn.
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So let's go back to our root. So I can say cd tilde and hit enter and now I'm back at my root directory
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which is here.
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So let’s map out the path that I need in order to get to here.
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I need to go into Documents and then Learn and then Languages. So I can simply write cd Documents/Learn/
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Languages/.
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And now if I hit enter I am inside Languages, which is over here. And that's a lot more succinct and a
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lot quicker than going through the directories one by one. Another really time saving feature of Terminal
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is the up and down buttons.
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So if you wanted to use the last command that you typed all you have to do is just hit the up button
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and you can see that I can use that change directory command again.
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But in my case I actually want to use the ls command.
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So obviously it's easier to simply type out ls rather than cycling through all those.
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But I just want to show you that you can actually go through your entire history of previous commands
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and you can then hit enter to execute it, and you can see that inside the Languages folder
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I have two other folders called German and IPA. So you can tell that we are at this level in our directory.
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Now sometimes typing out an entire path like this might seem like it's a lot of work.
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So I want to show you another neat trick that you can use when you have the Finder open and you just
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want to navigate to a deep directory without having to type out the entire path.
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So let's cd
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back to here,
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to our root directory for your user.
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So do you know how to do that? If you do, go ahead and do it now.
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So I'm going to cycle back and I found it.
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It's the cd tilde.
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And if I hit enter I am now back at my user’s root directory.
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Now once we're inside this Languages folder, how do we change directory back to the parent folders?
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How do we go backwards in this path?
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We're still going to be using the change directory or the cd command, and then after a space we're simply
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going to type two dots.
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And this takes us back one level,
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so from Languages I'm now in the Learn folder,
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so I'm now here. And I can keep doing this until I'm back at my root directory right here.
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So it took me three cd .. to get back to my roots.
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And the reason why you might want to do this is because, say if I was inside the Languages folder, so
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I'm now at the Languages directory, and I wanted to navigate
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now to my Music directory for example. I can't simply write cd Music. That’s not going to work because
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it's looking inside this Languages folder.
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It's looking to go forwards.
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So if I wanted to go backwards in the directory I either have to specify the entire file path,
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so that would be cd /, which is my Macintosh HD, Users/angelayu/Music.
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So I would have to specify the entire file path to go backwards and I can only specify just the name
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of the folder if I'm going forwards in terms of this hierarchy.
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Now what if I wanted to edit this at some point in the middle of this entire command? Because you can
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see that if I click at any of these places it doesn't really do what you expect it to do in a graphical
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user interface, right,
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namely allowing you to edit these parts. Your cursor is here and you can only type where your cursor
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is. So you can of course use the left arrow to go all the way back, but this is obviously very time consuming,
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especially if your command is very long.
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So a neat trick is holding down the option or the alt button and it gives you this little plus sign,
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and now you can click on one point in your command and you can now move the cursor to that position.
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So that's quite a neat trick as well.
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Now for people who have come from a long history of using graphical user interfaces such as you know
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your Mac OS or your Windows, having these little tricks like using the option click can be quite neat,
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but if you are a puritanical command line user then ideally you're aiming for never having to touch
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the mouse and you can do most things that you would want to do with the mouse very easily and quickly
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just using your keyboard.
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So for example if I wanted to go to the beginning of this line then I can simply hold down control and
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press A,
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so my cursor is now at the beginning. And if I hold down control and press E then I go to the end of my
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command line.
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Now you've already seen that I can cycle through my previous commands by using the up and down button.
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But what if I wanted to clear this current command without executing it?
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So to do that you can again hold down control and hit the U button, and that clears your entire line,
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so you can write a new command.
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So in the next lesson we're going to cover directories, making directories and secret folders.
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So I will see you there.