The command line is a text interface for your computer. Just like Windows Explorer on Windows or Finder on Mac OSX it let’s you navigate through the files and folders of your computer, but it is completely text based. The command line works by typing commands against a prompt, which then gets passed to the operating system of the computer that runs these commands.

To access the command line, we use a terminal emulator, usually called a terminal. On Mac OSX you can access the terminal by opening the Terminal application from your Applications folder. On Windows you should use a program called the PowerShell. To access the Powershell, click 'Start', in 'Search programs and files' type powershell, and hit enter. This should open up Powershell on your computer.

Before we get started, you should note some DO's and DONT's while using the command line. The command line is a powerful tool that can significantly speed up your workflow but can also irreversibly harm your computer so make sure you use it responsibly. If you are not sure what a command does DO NOT type it into your terminal. The command rm -rf / is a classic one that you should never use. If you are stuck and in need of help make sure you ask from someone you trust or other reputable sources. It goes without saying that all commands in this tutorial are safe to use.

Once you opened up your terminal, type in the following after the $ or > sign and hit enter: ($ or > is the prompt, you don't have to retype that in the terminal, only the characters that come after them):

$ pwd

What do you think happened there? In your own words, try to explain what this command does.

The pwd command prints out the current directory you are in. What are directories? Directories are folders, these terms are used interchangeably. If you just opened up your terminal, you are probably in the home directory of your computer, and should get an output similar to this:

/Users/your-username

Now you know how to tell where you are in the folder structure of you computer, you might ask yourself: but if there is no visual user interface in the terminal how do I know what directories are in what directories? That's where the ls command comes in handy.

In your terminal type:

$ ls

and hit enter. Most likely this command returned you a bunch of files and directories (folders). The ls command prints out the contents of a directory. If you are in the home directory of your computer you should see directories printed out such as Documents, Applications, etc. Now the question is, how do I move between directories?

The cd prompt allows you to move between directories. The cd command takes an argument, usually the name of the folder you want to change into, so the full command is cd your-directory.

In the terminal, type:

$ ls

Choose a directory you want to change into, and type:

$ cd your-directory

Now type:

$ pwd

This should return you the name of the directory you just cd into.

Type ls into the terminal, choose another directory and cd into it. We have just changed into a new directory. You can use these two commands to navigate around the directory structure of your computer. This is all good so far but sometimes you might want to go deeper than one level in one command. cd allows you to do this by chaining the directories with a /, so cd your-directory becomes cd your-directory/directory-inside-your-directory.

We now know how to move forward but how to go back up the directory tree? In your terminal type:

$ cd ..

Now do a pwd. You just went back one directory! Chaining works backwards too, so if you type cd ../.. you should be taken back two directories.

If you want to go back to the home directory of your computer, simply type cd into the terminal. cd without an argument takes you back to the home directory regardless of where you are currently in the directory structure

These are the basics of navigating around in the terminal. What else would we want to do in there? How about creating directories and files?

Go back to the home directory of your computer, and type:

$ mkdir temp

into the terminal. Now use ls to see the contents of the home directory. You should see a new folder, temp there. You just created a new folder! As it's name suggests, mkdir creates directories. What if we wanted to create a directory inside a directory? cd into temp and type:

$ mkdir -p stuff/bits

No do an ls and you should see stuff retruned. cd into stuff and do another ls. Inside stuff, the directory bits was created.

What if you wanted to create files?

Inside bits, type:

$ touch bobs.txt

Do an ls to check whether the file has been created. Inside bits, there should be a new file called bobs.txt. We used touch to create files. With touch you can create files with any extensions, just don't forget to specify what kind of file you are creating: index.html, script.js, style.css are all valid extensions.

$ say hello