- Explain how the IDE mimics the behavior of the shell
- Use
pwdto identify the current directory of your IDE session - Use
lsto list the files in the current directory of your IDE session - Use
cdandcd ..to change directories of your Nitrous Console session
When you open a file on your computer, you locate it by navigating through the directories on your computer's file system using Finder. Even files on your Desktop that you click on are stored in your computer's file system, your hard drive.
When you open an application from your Finder or Desktop, it always happens from the context of a "Working Directory" - the directory of your computer you were in when you executed the program. When you click on a file on your Desktop or Open an application from Your Dock or Applications directory, you are still opening a file in a directory. The Dock and Desktop are just abstractions for that directory to make them easy to access.
We're used to navigating and operating on these files using our GUI, our Graphical User Interface, provided by OS X (Macintosh) or whatever operating system we're using (Windows).
The terminal in your IDE doesn't allow you to access the files on your computer, but it does let you access all the files that you load on to your IDE. In other words, you can access all the labs that you load on to the IDE from Learn. This terminal provides us with a Command Line Interface to navigate and operate on the files and folders in our IDE. As programmers, the Terminal is our workbench, not the GUI.
Let's learn to navigate the files and folders on your IDE using the following commands. These commands are standards for all terminals (not just for your IDE).
When you open the IDE, your Terminal is open to a location within a directory of the file system. Whatever programs you execute or work you do in your Terminal, that action happens in the context of a "Working Directory."
A "Working Directory" just means wherever on your IDE you are when you execute a program by running a command in your Terminal like learn hello. You did that from somewhere. We call that somewhere, wherever you currently are, a "Working Directory".
Open your IDE and in your terminal, you'll be at your Command Line prompt, where your computer is waiting for instructions.
Our Command Line prompt, and maybe yours if you configured your environment through Learn, is represented by:
[16:19:43] code
// ♥
The first line, [16:19:43] code is telling us the current time, so expect that part to be different for you, and our current working directory, code. (This is different our Home directory which we'll explain later in this lesson.)
The next line, // ♥ is our command line prompt, where we can type instructions and commands for our computer to execute. // ♥ is a customized prompt that you got by setting up your environment through Learn. To us the symbols // ♥ remind us of the way, '//', of love, '♥'. That's our mantra when we're programming. And we think it looks pretty cool given how much time we spend in our Terminal.
More generally, the command line prompt is represented by a $.
If you've read other tutorials, you might be familiar with seeing command line instructions with a $ to represent the prompt. We try to follow this convention in our instructions but you might sometimes see // ♥ in images or code samples.
What can you do from a command line prompt? Everything and anything. A command line prompt is the most powerful interface in the world, from which every computer and piece of software can be created, controlled, molded, manipulated, and used.
Let's run the following command line program.
Type pwd from your prompt. You should see something like:
// ♥ pwd
/home/AnnJohn/code
[16:19:43] code
// ♥
Here we typed pwd and pressed Enter on my keyboard. The terminal responded with /home/AnnJohn/code and returned me to my current directory, code and gave use a new prompt, ♥.
That's the standard procedure when you execute anything in Terminal. You enter a command from a prompt in a working directory, see output, and are returned to a new prompt in your working directory.
The pwd command is an acronym for "Print Working Directory." The pwd command prints the working directory of your Terminal session, the folder you are currently "in."
Knowing what directory you are working within is crucial when using your Terminal. You are opening files and running programs that live in directories and you need to make sure you're in the right directory for your task.
You never need to guess, if you're ever curious where you are or need to confirm you are where you think you are, type pwd.
When you open a new Terminal session, you start in a default location in your file system.
'/' means the main directory of your IDE. Every file and folder on your computer lives somewhere inside of /.
/home is the main directory in the IDE. Within /Users, there is a folder for your username, the name of the Github account you used to login to your IDE. In this case, the username is AnnJohn so the home directory is: /home/AnnJohn/code. Yours will be different and you can see it by opening a new Terminal session and typing pwd.
code is the default directory in the IDE, whatever it may be.
Within a directory, one thing you're probably curious about is "what files are in this directory?". You can list files within your working directory by executing ls:
~ $ ls
Applications Development Desktop
Documents Downloads Public
When we type ls in Terminal, we're asking our Terminal to list the files and folders in the current working directory.
In my home directory, code, there are 6 directories, Applications, Development, Desktop, Documents, Downloads, and Public. The directories you have in the IDE will only be the labs that you've downloaded on there.
When you open a new Terminal session, you'll be in a working directory, probably code. But how do we move around to other directories and change our working directory? You can use the cd command, which stands for Change Directory.
From the code directory, try:
// ♥ cd labs
[16:19:43] labs
// ♥
From within code, at our prompt ♥, we type cd labs. Our terminal will change the directory and enter our labs folder and our prompt will now indicate that our working directory is code/labs. Your prompt might look a little different but you'll be in your Desktop directory. Confirm with: pwd. pwd should output something like: /home/AnnJohn/code/labs, the full path to your labs directory.
Once your working directory is labs, try ls and have your Terminal list any files that are in that directory.
How do you move from labs back up to your code directory? You can always move out of the current folder and back into the parent folder by typing cd ... .. is a shortcut that always means "the directory above" or the "parent directory" of the current. Your file system is a tree like structure, with directories being inside other directories:
├── code
├── labs
labs is within code. From within labs, you would refer to the parent directory, code as ...
In the same manner that .. means the directory above, the shortcut . means the current directory. You'll see why being able to refer to your current directory as . is helpful in a minute.
You can also change directory back to your home directory from anywhere via cd ~. ~ is a shortcut that means home so if you type cd ~ you are telling your terminal to change the working directory to your home directory. Try it now.
Then enter ls and you'll see the code directory. Go ahead and cd back into it.
When you're in Terminal, to autocomplete a directory or a command, start typing and then press TAB.
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