Introduction to Command Line

Introduction To The Command Line

Getting started with Terminal

The Command Line is a text-based interface that allows you to communicate with your

computer to accomplish a wide range of tasks. You will use the skills you develop in this lesson

when working with Twarc, a command line tool for collecting and analyzing Twitter data. It is

important to have a handle on basic commands so that you can work with the 1 October

Twitter Data Collection later on in this tutorial series. Get started by downloading the materials

below!

Difficulty level: Beginner

Optimized for: Mac users. Windows users can view the tutorial here.

Prerequisite(s): None

Materials: Download ‘walt_whitman.zip’ to your desktop

Tutorial Key

● Command Line commands will be displayed in this format

● means you have come to the end of a set of instructions

Lesson objectives

- Use the command line to navigate your computer

- Create and move content around

- Make changes to existing files

Key Terms

● Terminal - OS X Command Line

○ A text interface for your computer. Terminal receives commands and then

passes those commands on to the computer's operating system to run.

● Command

○ A specific order from a user to the computer’s operating system to perform a

service

● Graphical-User Interface (GUI)

○ A visual form of user interface that allows users to interact with a computer

through icons and other visual indicators

● Filepath

○ A unique address that speciﬁes a location in a ﬁle system

● Directory

○ A location for storing ﬁles on your computer. A directory is the same thing as a

folder; a folder is represented visually in a GUI.

Table of Contents

Lesson objectives 1

Key Terms 1

Table of Contents 2

Introduction 3

Getting started 3

Moving Around Using Terminal 5

Manipulating Files Using Terminal 9

Review 17

Introduction

How do you create a new folder? Pick the option below that applies to you:

a. Right-click on my desktop and click ‘Create New Folder’

b. Click on the tool button and then click ‘New Folder’

c. Will it into existence, I have the power within me

d. I don’t. I like my files to be free range.

If you selected C or D, chances are you are probably not having much success organizing your

files. If you selected A or B, you are interacting with your system through a Graphical-User

Interface (GUI). Before users relied on GUIs to move around their systems, the command-line

interface was the primary way people would interact with their computers. While a GUI is a

visual way for operating your computer, the Command Line is a text-based interface for doing

the same tasks you perform when clicking, dragging, and dropping files. It has a range of

capabilities that make it a powerful tool for those who need more precision in their work. In

this tutorial, you will learn how to navigate your computer using the Command Line.

Getting started

There are two main command-line interfaces that are discussed in this tutorial series. On OS X

the shell is known as bash, or the ‘Bourne-again shell’. In OS X, the shell is located by default

in: Applications > Utilities > Terminal. Let’s get started by opening terminal.

Read through these tips and tricks before moving on to the next section:

Tips and tricks

● ‘$’ signals the shell prompt. You can tell when a process is complete

when it returns to the shell prompt.

● Capitalization and spacing matters! Make sure to always double check

your work.

● You can drag and drop folders into Terminal instead of typing out

their filepath

● Using the up arrow on your keyboard will recall commands. Use this

tip to waste less time writing out commands and lengthy filepaths.

● 0 moves your cursor to the start of the line

● $ moves your cursor to the end of the line

● You can copy and paste by right clicking in Terminal

Awesome work! You’re ready to start using Terminal. Scroll down to the next section.

Moving Around Using Terminal

If you are feeling lost after opening Terminal, it is important to find out where you are in your

filesystem. Go ahead and enter the following command to print the working (your current)

directory:

pwd

Nice job! Now let’s see which directories and files are available in your location by entering the

list files command:

Let’s change directories. Navigate to your desktop by entering the change directory

command:

cd Desktop

If you haven’t already, go ahead and click here to download the zip file we will be working

within this tutorial to your Desktop. After you’ve downloaded the file, let’s create a directory

that we can store the file in by entering the make directory command:

mkdir walt_whitman

We’re going to move the ‘walt_whitman’ zip file you downloaded from your Desktop into your

‘walt_whitman’ directory by using a new command, move:

mv walt_whitman.zip walt_whitman

Note: If you’re having trouble with this step, double check to make sure you moved the

‘walt_whitman.zip’ file from your to your downloads folder to your Desktop.

Navigate to your new directory using the change directory command:

cd walt_whitman

Good job! You’re ready to move on to the next section.

Manipulating Files Using Terminal

Now that you know how to find your location in a filesystem, we’re going to edit and move

individual files around. We’re going to start with the ‘walt_whitman’ zip file on your Desktop.

Double check to make sure that you are still in your ‘walt_whitman’ directory using the print

working directory command:

pwd

To get started, we need to unzip the file. Enter the unzip command to do so:

unzip walt_whitman.zip

Let’s see what’s inside. Use the list files command:

What you should see:

1_Poems.txt 2_Poems.txt 3_Poems.txt 4_Poems.txt readme.txt

walt_whitman.zip

What a treat! You’ve unzipped four poems and a README plain text file. Let’s find out how

many lines and words are in the file ‘1_Poem.txt’ by using the word count command:

wc -l -w 1_Poem.txt

There are 397 lines and 2,451 words in the first poem.

Let’s find out which poem it is! Start by using the tail command, which pulls up the last 10

lines of a text:

tail 1_Poem.txt

What you should see:

of woe,

With the holders holding my hand nearing the call of the bird,

Comrades mine and I in the midst, and their memory ever to

keep, for the dead I loved so well,

For the sweetest, wisest soul of all my days and lands—and this

for his dear sake,

Lilac and star and bird twined with the chant of my soul,

There in the fragrant pines and the cedars dusk and dim.

https://whitmanarchive.org/published/LG/1891/clusters/192

So that didn’t give us the title, let’s try and see if using the head command to get the first 10

lines of a text will help:

head 1_Poem.txt

What you should see:

WHEN LILACS LAST IN THE DOORYARD BLOOM'D.

WHEN lilacs last in the dooryard bloom'd,

And the great star early droop'd in the western sky in the night,

I mourn'd, and yet shall mourn with ever-returning spring.

Ever-returning spring, trinity sure to me you bring,

Lilac blooming perennial and drooping star in the west,

Looks like we tracked down the title of the poem. Let’s rename the file to match the poem’s

title. You can do this using the move command you learned earlier:

mv 1_Poem.txt when_lilacs_last.txt

Let’s check out the ‘readme.txt’ file to see if it tells us about any of the other poems. You can

open the file by using the cat command:

cat readme.txt

Note: The cat command will read a file, but it can also combine files

Looking at the README file we see that the other three poems are part of Walt Whitman’s

‘Memories of President Lincoln’. If you want to read the other poems, you know how to open

them using the cat command.

Before we exit Terminal, let’s get rid of the ‘walt_whitman.zip’ file since we don’t need it

anymore. Do this by entering the remove command:

rm walt_whitman.zip

Since we’re all done in this directory, navigate up one directory to your Desktop by entering

the change directory command:

cd ..

Home sweet Desktop. List the files one last time to make sure everything is in the right place.

We’re good to go! Go ahead and leave Terminal by entering the exit command:

exit

Fantastic work! You’ve completed the tutorial.

Review

Reference the table below to review the material we covered in this tutorial.

Command:

Stands for:

Does what?

pwd

working

directory

Lets you know where you are in your file system

List files

Lists the files in your current directory

Change

directory

Changes the current directory

cd ..

Navigate up

Navigate up one directory from the current

one

directory

mkdir

Make

directory

Creates a directory

Move

Moves a file, can also be used to rename a file

Remove

Deletes a file

head

Head

Shows the first ten lines of a file

tail

Tail

Shows the last ten lines of a file

cat

Concatenate

Will read a file; can also combine files

exit

Exit

Exit Terminal