Navigating Directories

Command Line Interface

Some of what we’ll be doing in class will involve interacting with your computer through a “Command Line Interface.” Command line interacts are purely text based way to interact with your computer. It’s your same exact computer, just a different way of using it without using icons, or clicking. 

macOS

In macOS, we can access a command line interface using the program Terminal. You can find Terminal in your Applications inside the folder called Utilities, or just by typing in “Terminal” into Spotlight search.

Windows

For now, on Windows, I’d recommend using PowerShell. You can launch PowerShell by searching for it in the Start menu.

Getting your Bearings

When you first launch your command line interface, it will look something like this:

Command Line Interface

This is obviously scary looking, and it doesn’t give you much hint as to what to do next. The important to thing to keep in mind is that while you are using the command line interface you are inside of a folder. There are two commands I recommend using over and over again to figure out where you are, and where you can go.

“The Prompt”

We call the the space waiting for us to type in something the “prompt”. It usually has a symbol before it. Depending on your system, it might be any of the following: $, %, or >. If you type something in here, your computer will interpret it as a command, and try to run it. 

pwd

If you type in pwd into the terminal and hit enter, it will print out the absolute path to where you currently are. When you first launch a terminal, it usually starts you off in your home directory, which is usually going to be named after your username.

bash

pwd

/Users/Display

Use pwd early, and use it often. It stands for present working directory. 

ls

If you type in ls into the terminal and hit enter, it will print out a list of all of the directories and files inside the folder you are currently in. Here’s how it prints out on my own computer when I first launch Terminal:

bash

ls

Desktop      Library    Pictures
Documents    Movies     Public
Downloads    Music      Sites  

Each of the items listed here is another directory inside of my current directory. I can look inside and get a list of all the files inside of these directories by typing in ls and the name of the directory I want to see inside of. For example, if I wanted to get a list of all of the files on my desktop, this is what I would type:

bash

ls Desktop

Sampletext.txt

I only have one file on my desktop right now, and it’s a document called Sampletext.txt. 

Know your surroundings

Really skilled and accomplished programmers use the commands pwd and ls constantly, and so should you! It’s the only way to keep track of your surroundings on the command line. 

If you ever are looking at a terminal, and don’t know what to do next, just type in pwd and ls. 

Every time you do a new thing in the terminal, type in type in pwd and ls afterwards.

Just type in pwd and ls all the time. :::

Getting around

You’re not always going to want to hang around in your home directory the whole time. You may want to get to a specific directory where some code or a script is to run it. To do this, we use the cd command, which stands for change directory.

cd : Moving down 1 level

To change the folder you’re in, you just need to type in cd and then the name of the folder. For example to move from my home directory into my Documents folder, it would look like this:

bash

ls

Desktop     Library   Pictures
Documents   Movies    Public
Downloads   Music     Sites

bash

cd Documents
ls

FranklinInstituteSamples.pptx   Zoom
FranklinInstituteSounds         html_practice

bash

pwd

/Users/Display/Documents

1. First, I double checked which directories were in the folder I was currently in with ls.
2. Second, I moved into the Documents directory with cd Documents.
3. Third, I checked what files and directories were in my new location with ls.
4. Fourth, I double checked my current location with pwd, which gave my the absolute path to where I was.

cd : Moving up 1 level

If after moving into my documents folder, I wanted to move back to my home directory, that would involve moving up one level, because my Documents folder is inside of my home directory. We can do this using cd again, but instead of the name of a directory, we follow it with ... The two dots, .., is a short hand for “one level up from where I am.” Here’s how that works out on my system.

bash

pwd

/Users/Display/Documents

bash

cd ..
pwd

/Users/Display

1. First, I double checked where I was with pwd.
2. Second, I moved up one level with cd ..
3. Third, I double checked where I would up with pwd again, confirming that I was now in my home directory again.

cd : Moving down multiple levels

You don’t have to move down just one level at a time. For example, right now we’re in my home directory, but inside of my documents there’s a directory called html_practice. That’s two levels down. To get into html_practice, I just need to enter cd followed by the relative path to it. Remember, the relative path is the sequence of directory names that lie between where we are and where we want to go. Here’s how that looks on my system.

bash

pwd

/Users/Display

bash

cd Documents/html_practice
pwd

/Users/Display/Documents/html_practice

bash

ls

site.html  style.css

1. First, I double checked my location with pwd
2. Second, I moved down two levels through Documents into html_practice with cd.
3. Third, I double checked where I had moved to with pwd.
4. Lastly, I checked what files were in my new directory with ls.

Moving up and over

Now, we’re inside html_practice which is inside Documents. But what if we wanted to move into another directory that is also inside of Documents. For example, the directory Zoom is also inside of Documents, which is where Zoom saves all of the chat logs from our class meetings.

Where we want to move

We could do this in a two step process, using cd .. to move up one level, then cd Zoom to move into the zoom directory. But we can also combine the two into one step.

bash

pwd

/Users/Display/Documents/html_practice

bash

cd ../Zoom
pwd

/Users/Display/Documents/Zoom

1. First, I double checked where I was with pwd.
2. Then, I moved up into Documents and down into Zoom in one go with cd ../Zoom
3. Finally, I double checked where I wound up with pwd.

Very useful tips!

There are a few tips, tricks, and shortcuts that can make using the command line a little bit easier.

Tab autocomplete

When using a command line interface, “tab autocomplete” is a crucial tool to help you get around. For example, if you are in your home directory and you want to move into your documents directory, all you really need to type is cd Doc and the terminal should autocomplete the rest of the file name! 

If you have multiple directories that start with Doc, it will list all of them, and then you’ll only need to type in a few more characters before it will be able to autocomplete. 

Tab autocomplete works for ls as well, which can let you explore through directories without needing to move around.

Get back home!

Technically, your home directory is a directory with a long absolute path. But because it’s a directory you’ll probably want to keep getting back to often, there’s a shortcut built in. If you run cd ~, it will zip you back to your home directory from wherever you are.

Absolute paths

If, for some reason, you don’t know what the relative path is to a directory you want to get to from where you are (or maybe it’s very complicated), you can always run cd followed by the absolute path to where you want to go.

This is all going to matter a lot

Using the command line and navigating your computer is going to come up a lot more in this course. You should try as much as you can to get a handle on how this all works now.