TerminalA program that allows a user to interact with The Command Line
A ShellA low level interface for your computer. Instead of pointing and clicking on things, you type words and run commands
The Command LineThe same thing as a shell - often used interchangeably
bashA particular type of shell found on Unix systems
DirectorySame thing as a Folder
command- A set of instructions for the computer to execute - provided via the command line
argument- A piece of information needed to run a certain command ie.
touch sample.txtwhere sample.txt is the argument
flag- An optional argument usually prefixed by a
ls -awhere -a is the flag
A note on interchangeable terms above
Most people use the terms
command line, and
That’s okay! The problem comes when they’re used incorrectly.
Here’s a few examples of correct usage:
- “Can you increase the font size of your terminal?”
- “We need to open up the command line here.”
- “Let’s use the shell for this task.”
- “I don’t like using bash - I think fish is better”
Additionally, there’s a Mac application just called
Terminal. That’s a specific program that accesses the command line.
You’re not as fast as you think
You probably grew up around computers, but if you’re like most of the non-developer population, you may have never touched the terminal. Why would you need to? Everything you need to do can be done on the desktop or through the Finder, and only super nerds use the terminal anyway. Right?
You might be thinking to yourself “Hey, wait a minute! I’m pretty darn fast when it comes to using my mouse to get around. Why do you think I need to use the terminal?”
Efficiency and Competency Show
It turns out you actually aren’t fast enough. As a developer everything you do should be based on speed and efficiency. When any part of your work flow is lacking you are wasting time. Over the course of a day, every extra second compounds into time you aren’t spending doing productive work. Not being a fluent user of your command line is a pain point that may not be terribly noticeable as you first start writing code and you’re still gaining momentum, but over time as you work more quickly you (and your pairing partners) will absolutely feel it. In an interview or workplace environment not being able to effectively use your terminal is a red flag. That means it’s important to start flexing our command line muscles right away to build understanding and comfort with this tool.
Some things must be setup in the terminal
Additionally, some of the tools you will use as a developer can only be used through the terminal and not by clicking in a program. You’ll use those tools in the terminal soon enough!
The terminal seems scary at first - no graphics, all text, little to no feedback, and you might be worried about deleting everything in your computer.
Don’t worry! You aren’t going to break your computer. It’s easy to fear the unknown and let it keep you from learning how to efficiently use the terminal. But if you push past the first day or two of feeling uncomfortable, you’ll become great at using the terminal in no time.
When you’re first starting to learn anything coding related, you have to build up your muscle memory. It’s totally normal to start slow and improve with focused practice and repetition. You’re not going to learn unless you actually get your hands dirty and dive right in!
Let’s actually start working on some basic interactions with our files using the terminal. We’re going to assume that you’re using a Mac for this lesson.
Open your terminal using
command + spacebar, then type
terminal, and press
enter. The mysterious black window appears…
Side Note - Keyboard Shortcuts for Efficiency
command + spacebar will open your spotlight search
command + tab will take you to your most recent open application
Observe the File Structure:
When you open up your terminal, you aren’t greeted with much. It just says your name and that’s about it. Typically when you open up your terminal you are brought to your root directory. Directory is just another word for folder. Your root directory usually contains:
|- Applications |- Documents |- Desktop |- Music |- Pictures
(and other directories depending on your computer)
pwd (print working directory)
We can use our terminal to navigate through our computer’s directories.
Let’s first get a handle of where we are in our computer’s file structure. To see where you are located in the file structure, enter
pwd in the terminal. This stands for your present working directory. If you are in the root directory, it will most like say
/Users/[your name]. If you ever forget or are confused about where you are, then use
pwd to find out!
Our file structure is made up of files and directories. Just as you would see visually in Finder or the Windows File Explorer, files and directories can live inside other directories, which you can picture as:
|- first-level-dir |-- second-level-dir |-- another-dir |--- third-level-dir (that is under/within `another-dir`)
In the terminal, we don’t have Finder to visually tell us what is contained within a directory or nested directories, but we do have commands to tell us.
We can use the command
ls to list the content in our current directory. You can see directories and files in the current directory, but you cannot see directories and files that are inside other directories.
Open your terminal and enter the command
pwd. What do you see? Can you find this same location using Finder?
Enter the command
ls. What directories and files do you see?
ls -la. How does this list change? Do you see the same files and directories when you use Finder?
For a more detailed list of content, type
ls -la - note the space between the characters. The addition of
-la gives more information about when that file or directory was last modified, permissions, and also lists hidden files/directories.
Make Folders & Create/Remove Files:
mkdir (make directory)
Creating a folder/directory is something that you will be doing often. A way to create a new folder is using the
mkdir [dir name] command. What this will do is create a new folder for us with whatever name you want to give it.
Note: A common way to document how to use a command is the command name,
mkdir, and then something within square brackets,
[dir name]. The first part,
mkdir, is the text that the terminal recognizes as a command. The second part,
[dir name], is the part where you will specify the new directory’s name. The square brackets mean that this is a place for you to fill in your own information, but you do not include the square brackets.
For example, let’s create a new directory called
mkdir pizza in the terminal.
One thing that you have to keep in mind is that in this process you won’t really get a prompt if you did the thing right. Typically if there is no output to the terminal when you do the correct thing.
How do we check that the directory was made? Use
ls to check that it is listed.
Keep in mind that even though you’ve created this folder, it doesn’t mean you are inside of that folder you’ve just created. To actually go into our new folder, you need to change into that new directory, but we will talk about this in the next section.
touch (create file)
Similar to directories, we also need to be able to create new files. The command we are going to use to do this is the
touch [file name] command.
Let’s make a new, blank text file using
touch toppings.txt. If we open the file, there is nothing in it, but we expect that because we only told the terminal to create a new file.
So we can make directories and new files, but we want to be able to remove them. That is where the
rm command comes in. If we’re not happy with our
toppings.txt file, then we can delete it.
rm toppings.txt into the terminal, and poof, it’s gone! As you can see there was no warning like, “Are you sure you want to delete this file?…” Be careful with this command because you can’t undo it.
Open a new terminal window. Create five different directories (with different names). Double check that all of the directories are listed in your current directory. Delete all the directories.
Create ten new files with different file names. Double check that all the files are listed in your current directory. Delete all the files you just created.
Move Through the File Structure:
cd (change directory)
If we are in our root directory, and we want to see what files are within the Pictures directory, we currently don’t have a way to do that. For instance, if we are in the root directory, and we enter
ls in the terminal, it will just list the files and directories in the root directory, but we cannot see what is inside Pictures by only using
To see what is in other directories, we can move around and navigate through our file structure. We want to change into the Pictures directory to see what is inside it.
To change our current directory, we use the command
cd [directory name]. We can move through directories in two directions: up or down - to a previous directory or to a nested directory. Let’s see this visually with sample directories.
|- turing |-- notes
From the example above, if your current directory is
turing and you want to move to
notes, then you would enter
cd notes into the terminal. We our changing our current directory to the
notes directory. Usually, you would say that you are going down into the notes directory.
If you want to go back to the
turing directory, then simply use two periods:
cd .. to go back up one level. With the previous example where you are currently in the notes directory, you would type
cd .. to get to the
You might be thinking to yourself, “Wow, I’m doing a lot of typing…and if I type something incorrectly in the terminal, then I’ll go to the wrong place or nowhere at all.”
Tab Autocomplete & Nested Directories
Tab completion is your friend when you don’t want to type an entire directory name or you don’t quite remember how something is spelled. What I mean by that is if you’re trying to change directories or
cd anywhere, if you start typing the first part of where you want to go and then you hit
tab, then the terminal will autocomplete the rest of the desired directory for you.
For example, in the directory structure:
|- turing |-- notes
If you are currently in the
turing directory and you want to go to notes, then just type
cd n and hit
tab. The terminal will autocomplete for you and your command will become
cd notes. Then hit
enter to run the directory change.
What if you want to change to a directory that is inside another directory? You can imagine that using
cd multiple times would get tiring and slow. What’s really cool is if we have something multiple levels deep we can keep adding directories to our
cd command. Say we have:
|- turing |-- notes |--- first-lesson
If we’re in
turing and we want to get to
first-lesson quickly, then we can do this with one command:
Note that each directory is separated with a slash,
/. If you wanted to add another directory, then it would be something like:
Likewise, we can also go back up multiple directories using one command. If you are in the
first-lesson directory and you want to go back to the
turing directory, then you can use the double dots as before with the slash separator:
In your terminal, change to your root directory. Your root directory is noted as a
~symbol. So the change directory command would be
cd ~. From there,
cdinto your Documents folder.
Once you’re in your Documents directory, list the contents of the Documents directory.
In your Documents directory, make a new directory of your choosing. Change into that directory, and make another new directory. Repeat this five times. When you are done, delete the directories you just made, one directory at a time.
Commands From Your Present Working Directory
cd, you can move around directories and add files in the directories where we need them. However, moving around to other directories can get tedious and time consuming.
From our present working directory, you can add files or directories anywhere in our file system by adding our “directory path” in our terminal commands.
Going back to
touch, you can chain on directories if you want to add files inside other directories. Say you have these directories:
|- turing (your present working directory) |-- mod1
If your present working directory is
turing, then you can create a new file inside
mod1 using one command:
touch mod1/new-file.txt. This command includes the directory and then the new file you want to create. You don’t have to
mod1. With this command, you end up with:
|- turing |-- mod1 |--- new-file.txt
The same can be done with making new directories. With our current running example, let’s add a directory inside the
mod1 directory. Again, if your present working directory is
turing, then you can do this with one command:
mkdir mod1/new-directory. We end up with:
|- turing |-- mod1 |--- new-directory |--- new-file.txt
Change to your root directory if you are not there already. How do we do this? With these next tasks, do not change into other directories. Keep your root directory as your present working directory.
Make three nested directories.
In each nested directory, create a file.
Remove all of the directories and files that you just created - one directory at a time.
Copy and Move Files/Directories:
So now that we can create and remove files, let’s add to our toolbox the ability to copy or move files. At a high level,
cp keeps the source file and copies the file to a new location.
mv takes the source file and moves it to a new location.
The copy command,
cp, has two options you need to enter:
cp [the thing you want to copy] [where you want to copy it to], or more simply
cp [source] [destination].
If we have a file named
sample.txt in this
turing directory, and we want to copy it inside the notes directory, then we can use this series of terminal commands.
|- turing |-- sample.txt |-- notes
|- turing |-- sample.txt |-- notes |--- sample.txt
If we are in the
turing directory, then this is how we move the file:
cp sample.txt notes/
Similarly, if we want to move a file, then we use the
mv command with
mv [source] [destination]. It’s almost the same as copy, but as you can guess, the file is moved instead of copied.
Like in the example before, if we want to move the file instead of copy it into the notes directory, then we could say
mv sample.txt notes/ to end up with:
|- turing |-- notes |--- sample.txt
Make a few nested directories with blank files in them, and move files around from directory to directory.
Can you figure out how to rename a file using the
mv command? How about
Copy Paste for File Contents:
It’s likely that copy-and-pasting is a big part of your life. You might think that doing something like this is in the terminal could be frustrating. In actuality it’s not that difficult.
In this case
pbcopy < [file] &
pbpaste > [file] copies the context of one file and pastes the contents into another file.
For example, let’s say we have a file
hello.txt with the content
Hello World! written inside of it, and we want to copy that text into a file named
Start by copying the contents from
pbcopy < hello.txt
And paste it into the
pbpaste > aloha.txt
aloha.txt file has the contents
From this point forward, you should not be using the Finder. Challenge yourself to use the terminal for navigation. It will be painful at first, but you can’t get fast without starting slow.
Being fast in the terminal will help you in your evaluations at Turing.
Take some time to review this cheatsheet of commands
You don’t need all of the commands, or even most of them - but try out a few that seem interesting to you.
The documentation for each command in the terminal is available if you type
man [command]. For instance,
man cd. Once you’re done viewing the manual page, enter
q to exit.
If You Are Feeling Like You Need More Practice
Use this short course to practice: Learn the Command Line from Code Academy
If You Are Feeling Pretty Comfortable
Continue on and complete the Advanced Topics section of this lesson below
Advanced Topics (Optional)
Customizing Your Terminal
A little bit of increased efficiency in your use of the Unix environment and your editor can pay significant dividends over time. Let’s experiment with customizing and adding to your terminal and editor.
- You can check out dotfiles on GitHub to see how serious people get: http://dotfiles.github.com/
exportto set environment variables
aliasfor shorthand commands, like I define
eto launch my editor
sourceto run scripts of bash commands
Snippets from Jeff’s
.bash_profile are below.
The top three lines setup a yellow lightning bolt as my prompt because, well, it’s awesome.
export PS1="\W \[\033[0;33m\]⚡\[\033[0;39m\] " export CLICOLOR=1 export LSCOLORS=ExFxBxDxCxegedabagacad
Check out this ezprompt generator and try to create a prompt for yourself
Can you add emoticons? Yes. Yes you can
Persisting Your Changes
~/.bash_profilein a text editor (ex:
Anything that you type into your terminal will only persist for the lifetime of the terminal session. If you want to save your bash prompt, you’ll do so by adding the commands you put in your terminal to your .bash_profile file.
Try adding your bash prompt to the to the
Close your terminal and reopen, see if it still works!
A shortcut for getting back to our “Module 1” directory
alias m1=”cd ~/turing/1module”
Test it out by typing
m1 into your terminal
Create a shortcut to the file path that you actually use to store your coursework!
Note: Make sure you get a specific alias that isn’t already being used for something else. You can find out if it’s already used by just typing it into your terminal and making sure you get a
command not found back!
Enable git’s tab-completion library
You can also create aliases for git if you are so inclined
Example shortcuts for git:
alias ga="git add" alias gb="git branch" alias gd="git diff --patience --ignore-space-change" alias gh="git log --pretty=format:\"%Cgreen%h%Creset %Cblue%ad%Creset %s%C(yellow)%d%Creset %Cblue[%an]%Creset\" --graph --date=short" alias gc="git checkout" alias gs="git status"