Week 2 · Session 1

The Terminal and the File System

Moving around your computer by typing instead of clicking.

Where Your Files Live

Files are stored inside folders, and folders can hold other folders
Directory is another word for folder. They mean the same thing, and you will see both
A folder inside another folder is a subfolder, or subdirectory
This nesting forms a tree, from your whole disk down to a single file
The folder you are working inside right now is the working directory

Opening the Terminal in VS Code

Two ways to do the same thing. Use whichever you remember.

From the menu bar: Terminal then New Terminal
Or by keyboard, Windows and Linux: Ctrl + `
Or by keyboard, macOS: control + `
A panel opens at the bottom. You type a command, press Enter, and it responds

Three Commands to Move Around

The names are abbreviations, and most of them are built on the word directory.

pwd is print working directory: the full path of the folder you are in now
ls is list: the files and directories inside the working directory
cd NAME is change directory: it moves you into the folder called NAME
cd .. moves you up one level, into the directory that contains you

If You Do Not Know Where You Are

Run pwd. It prints your exact location
Run ls. It prints what is in that location
Run cd .. to move up one level at a time
cd with nothing after it returns you to your home directory

Files Whose Names Begin With a Dot

A file or directory whose name starts with . is not shown by ls
ls -a lists all entries, including those
The -a is an option: extra instructions for the command
Nothing about the file is protected. The name only changes whether ls displays it
Course folders you download will contain some. You will need ls -a to see them

Making Folders From the Terminal

mkdir NAME is make directory: it creates a folder called NAME inside the working directory
It creates the folder only. It does not move you into it
Use cd NAME afterwards if you want to go inside
Run ls to confirm the folder is actually there

Set Up Now

Your Folder for This Course

One folder for the course, with a subfolder for activities and one for labs. Everything you download this semester goes into one of the two.

cmpsc100/
activities/
labs/

Building It, One Command at a Time

Type these one per line, pressing Enter after each.

pwd check where you are before you create anything
cd Desktop or wherever you keep your coursework
mkdir cmpsc100 create the course folder
cd cmpsc100 move into it
mkdir activities then mkdir labs
ls you should see both subfolders listed

Install Now

One More Tool: Git

We did not install this in the Week 1 setup, so we are doing it now.

Windows: download and run the installer from git-scm.com/download/win
macOS: run xcode-select --install and accept the prompt
Some Macs already have it. The command will say so, and that is fine
When it finishes, close and reopen the terminal, then run git --version
A version number means it worked. Full steps are in the Setup Guide, section 5

Git is a program that records the changes you make to files in a folder
A folder that Git is recording is called a repository, usually shortened to repo
Each time you save your progress, Git stores that version and keeps the earlier ones
If you break something, the version that worked is still there to go back to
Git runs on your own computer and does not need the internet

Git and GitHub

Git is the program on your computer that records changes
GitHub is a website that stores repositories online, so they are backed up and shareable
You made a GitHub account during the Week 1 setup lab
Every activity and lab in this course is a repository on GitHub. You will be given a link to each one
This is how you receive your work, and how you hand it in

Clone: Getting a Repository Onto Your Computer

Cloning downloads a copy of a repository, and remembers which GitHub repository it came from.

git clone URL downloads the repository into your working directory
It arrives as a new folder, so cd into the right place before you run it
Activity repositories go in activities/, lab repositories go in labs/
Run ls afterwards to confirm the new folder is there

Commit and Push: Handing Work In

git add FILE marks a file to be included in your next save
git commit -m "what I changed" saves a snapshot of those files on your computer, with a short note
git push uploads your saved snapshots to GitHub
Commit as often as you like. Each one is a point you can return to
Your work reaches us only after you push. A commit on its own stays on your laptop