Terminal Fundamentals

Opening Your Terminal#

First things first

Mac#

Press Cmd + Space to open Spotlight, type Terminal, and hit Enter. That's it.

Other options: iTerm2 or Wezterm (if you've installed them). They all do the same thing.

Windows (WSL)#

Open the Start menu, type Ubuntu (or WSL), and hit Enter. You should see a dark window with a blinking cursor.

If you don't have WSL installed, see the Environment Installation guide first.

Windows (Git Bash) — Quick Start#

If you don't have WSL set up yet, Git Bash is a quicker alternative to get started learning the terminal. Download it from git-scm.com/downloads/win, install with the default options, then open the Start menu, type Git Bash, and hit Enter.

Git Bash and WSL both use the same commands (Bash). Everything in this guide works identically in either one. For a full dev environment, we recommend setting up WSL when you're ready — but Git Bash is perfect for learning the fundamentals.

The terminal is just a text-based way to talk to your computer. Instead of clicking folders, you type commands. Everything you can do by clicking, you can do here -- faster.

1

Finding Your Way#

~10 minutes · Absolute beginner

01 pwd -- Where am I?#

Prints the full path of the folder you're currently in (your "working directory").

pwd

/home/yourname

On Mac you'll see something like /Users/yourname

02 ls -- What's here?#

Lists the files and folders in your current directory.

ls

Desktop Documents Downloads Pictures

You'll see your own folders listed here.

For more detail (hidden files, permissions, sizes), add -la:

ls -la

drwxr-xr-x 5 you you 4096 Feb 26 10:00 . drwxr-xr-x 3 you you 4096 Feb 26 09:00 .. -rw-r--r-- 1 you you 220 Feb 26 09:00 .bashrc drwxr-xr-x 2 you you 4096 Feb 26 10:00 Desktop

Files starting with . are hidden files. -la shows them.

03 cd -- Moving around#

Changes your current directory. Think of it as double-clicking a folder.

Go into a folder:

cd Desktop

Go up one level (back to the parent folder):

cd ..

Go straight to your home folder from anywhere:

cd ~

~ is a shortcut that always means "my home folder." You'll see it everywhere.

Where is "home" on different systems?

• Mac: /Users/yourname
• Linux: /home/yourname
• WSL: /home/yourname — this is inside the Linux filesystem, not your Windows user folder. To access Windows files from WSL, use /mnt/c/Users/yourname
• Git Bash: /c/Users/yourname (your normal Windows home)

If you save a file on your Windows desktop but can't find it in WSL, that's why — they're separate filesystems. Use /mnt/c/ to bridge them.

04 mkdir -- Creating folders#

Creates a new folder (directory).

mkdir my-project

No output means it worked. Run ls to see your new folder.

05 touch -- Creating files#

Creates a new empty file.

touch hello.txt

No output means it worked. Run ls to confirm the file exists.

06 clear -- Clean the screen#

Clears all the text from your terminal. Your files are untouched -- it just tidies up the view.

clear

Your terminal will be blank. Scroll up if you need to see previous output.

Practice Exercise: Build a project folder#

Copy and paste each command one at a time. After each one, look at what happened before moving to the next.

cd ~

mkdir terminal-practice

cd terminal-practice

pwd

mkdir src

mkdir docs

touch README.md

touch src/app.js

touch docs/notes.txt

ls

ls src

ls docs

tree

README.md docs src

. ├── README.md ├── docs │ └── notes.txt └── src └── app.js

tree shows your entire folder structure at a glance. You just built all of this from the terminal.

2

Working With Files#

~15 minutes · Getting comfortable

Make sure you completed the Level 1 exercise. We'll keep working in the ~/terminal-practice folder.

01 echo -- Writing text to files#

Writes text into a file. The > symbol means "put this into that file" (overwrites). >> means "add to the end."

echo "Hello from the terminal" > README.md

echo "This is line two" >> README.md

First command writes. Second command appends. No output is normal.

02 cat -- Reading files#

Prints the entire contents of a file to your screen.

cat README.md

Hello from the terminal This is line two

03 cp -- Copying files#

Makes a copy of a file. Original stays untouched.

cp README.md docs/README-backup.md

Run ls docs to see the copy.

04 mv -- Moving and renaming#

Moves a file to a new location. Also used to rename files.

Rename a file:

mv docs/notes.txt docs/session-notes.txt

Move a file to a different folder:

touch temp.txt
mv temp.txt src/

Run ls src to see temp.txt moved there.

05 rm -- Deleting files#

Permanently deletes a file. There is no trash can -- it's gone for good.

rm src/temp.txt

Be careful with rm. Double-check the file name before pressing Enter. Never run rm -rf / -- that would try to delete your entire system.

06 grep -- Searching inside files#

Finds lines in a file that contain a specific word or phrase.

grep "terminal" README.md

Hello from the terminal

Shows every line that contains the word "terminal."

07 Pipes | -- Chaining commands#

The pipe | sends the output of one command into the next command. Think of it as a conveyor belt.

ls | grep ".md"

README.md

Lists files, then filters to only show ones containing ".md".

08 which -- Where do programs live?#

Shows the file path of a program. Useful for confirming something is installed.

which git

/usr/bin/git

If nothing shows up, that program isn't installed (or isn't in your PATH).

09 echo $PATH -- Environment variables#

Environment variables are settings your terminal knows about. $PATH is the most important one -- it's the list of folders where your computer looks for programs.

echo $PATH

/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin

A colon-separated list of folders. When you type git, your computer checks each of these folders for a program called git.

Practice Exercise: Write and search a file#

Build a small file, then search through it. Copy each command one at a time.

cd ~/terminal-practice

echo "apples" > groceries.txt

echo "bananas" >> groceries.txt

echo "apple juice" >> groceries.txt

echo "bread" >> groceries.txt

echo "almond milk" >> groceries.txt

cat groceries.txt

grep "apple" groceries.txt

cat groceries.txt | grep "a"

apples apple juice

The grep "apple" command finds both lines containing "apple." The piped version finds all lines containing "a."

3

Power User#

~15 minutes · Stretch goals

01 Tab completion and arrow keys#

These two habits will save you hours. They don't require copy-pasting -- just practice.

Tab#

Start typing a file or folder name, then press Tab. The terminal auto-completes it. Try typing cd Doc then pressing Tab.

Up Arrow#

Press the up arrow to cycle through your previous commands. Much faster than retyping.

02 Ctrl+C -- Stop everything#

If something is running and you want it to stop, press Ctrl+C. It cancels the current command. This is your emergency brake.

Works for: stuck commands, running servers, accidental infinite loops. You'll use this daily.

03 && -- Chaining commands#

Run multiple commands in sequence. The second command only runs if the first one succeeds.

mkdir new-project && cd new-project && pwd

/home/yourname/terminal-practice/new-project

Creates the folder, moves into it, and prints the path -- all in one line.

04 Keyboard shortcuts#

These work in most terminals. Practice them while typing commands.

Ctrl+A Jump to the beginning of the line

Ctrl+E Jump to the end of the line

Ctrl+W Delete the word before the cursor

Ctrl+L Clear the screen (same as clear)

Ctrl+R Search through your command history (type to search, Enter to run)

05 chmod -- File permissions#

Controls who can read, write, or execute a file. You'll mostly use this to make scripts runnable.

echo '#!/bin/bash
echo "Hello from my script!"' > my-script.sh
chmod +x my-script.sh
./my-script.sh

Hello from my script!

chmod +x makes the file executable. ./ means "run this file from the current folder."

06 alias -- Creating shortcuts#

Creates a shortcut for a longer command. Only lasts for the current terminal session.

alias ll="ls -la"
ll

Now typing ll does the same thing as ls -la. To make it permanent, add the alias line to your ~/.bashrc or ~/.zshrc file.

07 ssh -- Connecting to remote machines#

Opens a terminal session on another computer. You'll use this when you have a server to manage.

ssh username@server-address

You'll be asked for a password (or it will connect automatically if you've set up SSH keys). Type exit to disconnect.

Don't worry if you don't have a server to SSH into. This is a "good to know" command for later.

Practice Exercise: Put it all together#

Create a mini project using everything you've learned. One command at a time.

cd ~ && mkdir my-first-app && cd my-first-app

mkdir src tests docs

echo "# My First App" > README.md

echo "Built from the terminal." >> README.md

echo 'console.log("hello world");' > src/index.js

echo 'print("hello world")' > src/main.py

echo "TODO: write tests" > tests/placeholder.txt

cat README.md

ls -la src/

grep "hello" src/index.js src/main.py

echo '#!/bin/bash
echo "Build complete!"' > build.sh

chmod +x build.sh

./build.sh

# My First App Built from the terminal. ... src/index.js:console.log("hello world"); src/main.py:print("hello world") Build complete!

You just created a full project structure, wrote files, searched them, and ran a script -- all without leaving the terminal.

Level 4

Why This Is Powerful#

Watch the terminal do in seconds what would take minutes by hand

01 Wildcards -- Select dozens of files instantly#

The * character means "anything". Instead of moving files one by one, you match patterns.

Let's create a mess, then clean it up in one command.

cd ~ && mkdir wildcard-demo && cd wildcard-demo
touch report.md notes.md todo.md
touch photo.png screenshot.png logo.png
touch data.csv results.csv
touch random.txt junk.log
ls

data.csv junk.log logo.png notes.md photo.png random.txt report.md results.csv screenshot.png todo.md

10 files, all mixed together. Now watch:

mkdir docs images data
cp *.md docs/
cp *.png images/
cp *.csv data/
tree

. ├── data │ ├── data.csv │ └── results.csv ├── docs │ ├── notes.md │ ├── report.md │ └── todo.md ├── images │ ├── logo.png │ ├── photo.png │ └── screenshot.png ├── ...

3 commands sorted 8 files into folders. Imagine doing that with 800 files -- same 3 commands.

02 For loops -- Do repetitive work automatically#

The terminal can repeat commands for you. Let's simulate a real scenario: you have a folder full of files from different years, and you only want this year's files.

cd ~ && mkdir loop-demo && cd loop-demo

# Create 20 fake files from different years
for year in 2023 2024 2025 2026; do
  for i in 1 2 3 4 5; do
    touch "${year}-report-${i}.pdf"
  done
done

ls

2023-report-1.pdf 2024-report-1.pdf 2025-report-1.pdf 2026-report-1.pdf 2023-report-2.pdf 2024-report-2.pdf 2025-report-2.pdf 2026-report-2.pdf ... (20 files total)

20 files. You only want the 2026 ones. One command:

mkdir this-year
cp 2026* this-year/
ls this-year/

2026-report-1.pdf 2026-report-2.pdf 2026-report-3.pdf 2026-report-4.pdf 2026-report-5.pdf

Done. All 2026 files copied, nothing else touched. The 2026* wildcard matched only files starting with "2026".

03 curl -- Grab things from the internet#

curl fetches content from a URL, right in your terminal. No browser needed.

# Fetch a webpage and see the raw HTML
curl -s https://example.com | head -20

# Download a file
curl -o test.html https://example.com
ls -la test.html

You'll see raw HTML in your terminal. The -s flag means silent (no progress bar), and head -20 shows just the first 20 lines.

Security note: You'll sometimes see install instructions like curl ... | bash. This downloads a script and runs it immediately. It's convenient, but you're trusting that URL with full access to your machine.

Only run curl | bash from sources you trust. When in doubt, download first (curl -o script.sh URL), read the file (cat script.sh), then run it. For more on staying safe, see the Security guide.

The point#

Everything above took seconds. Sorting 20 files by year. Organising a messy folder by file type. Downloading from the internet. These aren't toy examples -- this is what the terminal does every day.

When you're building apps with Claude Code, every command happens in the terminal. The more comfortable you are here, the faster you build.

Quick Reference#