Module 1: Linux setup & CLI#

You will:

  • Build ~/bridge-lab, your workspace for all four modules.
  • Read, copy and move files.
  • Write and run a Bash script.

New to terminals? Complete 1.1: Setup first, then return to the game.

Practice roadmap#

Start in the browser. Build confidence. Then try a real shell challenge.

Your next levelsA winding road connects four stops: CMD Challenge, ExplainShell, Linux Journey, and Bandit, ending at a finish flag.01020304
  1. Level 01 · Do

    CMD Challenge ↗

    Try the first few Unix command challenges in the browser.

  2. Level 02 · Decode

    ExplainShell ↗

    Paste a command and inspect what its arguments mean.

  3. Level 03 · Learn

    Linux Journey ↗

    Read the Command Line and Permissions lessons.

  4. Level 04 · Play

    Bandit ↗

    Use SSH after setup. Start with levels 0–3 in the game mission below.

Game mission: BanditRead a file. Unlock the next level. | 3 challenges

Start here#

  • Game: Bandit gives you a remote Linux computer.
  • Flow: each password unlocks the next account.
  • Goal: reach bandit3.

  1. Open your Ubuntu/WSL or macOS terminal. Check ssh -V.

  2. Connect to the official game host:

    ssh -p 2220 [email protected]

  3. On a first connection, check the hostname before accepting SSH’s host-key prompt.

  4. Enter the published starter password: bandit0. Password input is invisible.

  5. Check the prompt: bandit0 means you are on the remote computer.

  6. After exit, you are back on your computer.

Challenge 1: Read the ordinary file (0 to 1)#

  1. Run ls.
  2. Choose a filename that looks useful.
  3. Try reading it before opening the walkthrough.
Walkthrough: list, read, reconnect

On Bandit, run these separately:

ls
cat readme
  1. Copy the printed password into private notes outside bridge-lab.
  2. Exit and reconnect:
exit
ssh -p 2220 [email protected]
  1. Enter the password you found, not bandit1.
  2. Check: your new prompt names bandit1.

Challenge 2: Read a file called - (1 to 2)#

  1. Run ls and find the file named -.
  2. Predict how to identify that file explicitly.
  3. If cat - waits for keyboard input, press Ctrl+C.
Walkthrough: give cat a path
  1. Run cat ./- below and save the password before exiting.
  2. Run the remaining commands one at a time.
cat ./-
exit
ssh -p 2220 [email protected]
  1. Use the saved password at the next login.
  2. Check: your prompt names bandit2.
  • Why ./-? It explicitly identifies the file named - in this directory.

Challenge 3: Read a name containing spaces (2 to 3)#

  1. Run ls.
  2. Copy the filename exactly, including its spaces.
Walkthrough: quote the whole path
  1. Run the first command and save the password.
  2. Exit and reconnect with the remaining commands.
cat "./--spaces in this filename--"
exit
ssh -p 2220 [email protected]
  1. Enter the newly found password.
  2. Check: your prompt names bandit3.
  3. Run exit to return home.
  • Quotes: keep the filename’s spaces together.
  • ./: handles the leading dash.

Stuck?

  • Check the account number, password and port 2220.
  • Filename differs? Use ls and the official level instructions.
  • Connection times out? Your network may block that port.

Keep the skill:

  1. Record what ls, cat, ./ and quotes did in notes/shell.txt.
  2. Keep passwords out of that file.
  3. Try the next level using ls -la before looking up a solution.

Your lab#

  1. Open the sections in order.
  2. Predict, then run commands one at a time.
  3. Change one thing and compare the result.
1.1 · Open a terminal and install tools
  • Terminal: the window where you enter commands.
  • Shell: the program that interprets them.
  • Ubuntu: usually uses Bash.
  • macOS: usually uses zsh; these navigation commands work in both shells.

Choose your system#

Windows

  1. If Ubuntu/WSL is already installed, open it; skip installation.
  2. Otherwise, open PowerShell as Administrator and run wsl --install -d Ubuntu.
  3. Restart if prompted, then open Ubuntu from Start.
  4. Create a Linux username and password; password input is invisible.
  5. In PowerShell, run wsl --list --verbose and check Ubuntu uses version 2.
  6. Use the Ubuntu terminal for the remaining labs. WSL help.

Ubuntu

  • Open Terminal with Ctrl+Alt+T on the standard desktop.

macOS

  1. Press Cmd+Space and search for Terminal.
  2. Open it; you do not need WSL.

Paste shortcuts

  • Ubuntu/Windows Terminal: Ctrl+Shift+V.
  • macOS: Cmd+V.
whoami
pwd
uname -s

Check:

  • whoami prints your username.
  • pwd prints your current directory.
  • uname -s prints Linux (Ubuntu/WSL) or Darwin (macOS).

Useful keys:

  • Up: recall a command.
  • Tab: complete a name.
  • Ctrl+L: clear the view.

Install in Ubuntu/WSL#

sudo apt update
sudo apt install curl git nano openssh-client python3 python3-venv podman
  • sudo: requests administrator privileges.
  • apt update: refreshes the package catalogue.
  • apt install: installs packages after confirmation.
ToolYou will use it to
curl, openssh-clientSend web requests; connect with SSH
git, nanoRecord versions; edit text
python3, python3-venvRun Python; create isolated environments
podmanRun containers later; check installation here

Install on macOS#

Run these version checks:

  1. curl --version
  2. git --version
  3. nano --version
  4. ssh -V
  5. python3 --version
  • Git missing? Run xcode-select --install and complete Apple’s installer.
  • Python missing? Use the official installer; it includes venv.
  • nano missing? Use a plain-text editor for the named files.
  • Podman is optional here; see its macOS installation guide. Do not run apt on macOS.

Install uv on either system#

Use the official uv installer:

  1. Download it with curl.
  2. Inspect it with less; press q to exit.
  3. Run it with sh.
curl -LsSf https://astral.sh/uv/install.sh -o /tmp/tds-uv-install.sh
less /tmp/tds-uv-install.sh
sh /tmp/tds-uv-install.sh

curl options:

  • -L: follow redirects.
  • -sS: hide progress but show errors.
  • -f: fail on HTTP errors.
  • -o: choose the output file.
  1. Reopen Terminal.
  2. Check uv --version works.
  3. On Ubuntu, also check podman --version.
  4. If uv is missing, follow the installer’s PATH instruction; try $HOME/.local/bin/uv --version to locate it.
1.2 · Build and navigate your workspace
  • Path: a file’s address.
  • Absolute path: starts with /, the filesystem root.
  • Relative path: starts from your current directory.
  • ~: your home directory.
  • . / ..: the current directory / its parent.

Use a fresh folder name if bridge-lab already contains your work, and substitute it throughout these modules.

cd ~
mkdir -p bridge-lab/notes bridge-lab/scripts
cd ~/bridge-lab
pwd
ls
printf 'I can navigate.\n' > notes/navigation.txt
cat notes/navigation.txt
cp notes/navigation.txt notes/practice-copy.txt
mv notes/practice-copy.txt notes/renamed-copy.txt
ls -la notes
CommandEffect
cd, pwdChange directory; show where you are
mkdir -pCreate directories, including missing parents
ls -laList details, including hidden names
printf, catProduce text; display file contents
> / >>Replace a file’s contents / append
cp, mvCopy; move or rename
touch fileCreate an empty file if absent; otherwise update its timestamp
  1. Check both files contain the same sentence.
  2. Run cd notes, then cd ../scripts.
  3. Predict where you are; verify with pwd.
  • cd: changes directories; it does not create them.
  • Spaces: quote names, as in cd "class notes".
  • Case: match the filename’s spelling and case.
  • Home: typically /home/NAME on Ubuntu or /Users/NAME on macOS.
  • WSL: /mnt/c exposes the Windows C: drive; keep this lab in ~.

Delete only your copy#

  1. Return with cd ~/bridge-lab.
  2. Run rm -i notes/renamed-copy.txt.
  3. Confirm the disposable filename before typing y.
  4. Check notes/navigation.txt remains.
  • Terminal deletion usually bypasses the desktop trash.

Your turn:

  1. Create notes/shell.txt.
  2. Append a sentence with >>, then read the file.
  3. Explain why repeating > would lose the earlier sentence.
1.3 · Give a script permission to run
cd ~/bridge-lab
ls -l notes/navigation.txt
ls -ld scripts
nano scripts/hello.sh
  • Example: -rw-r--r-- splits into - | rw- | r-- | r--.
  • Groups: file type, owner, group, others.
  • Type: d means directory; - means regular file.
  • Permissions: r/w/x mean read/write/execute.
  • Directories: x permits traversal; your permission values may differ.

Paste this into nano:

#!/usr/bin/env bash
learner="Explorer"
printf 'Hello, %s!\n' "$learner"
pwd
  1. Save with Ctrl+O, then Enter.
  2. Exit with Ctrl+X.
  • The first line selects Bash for direct execution.
  • learner="Explorer" stores text; "$learner" reads it.
  • %s inserts that text; \n ends the line.
bash scripts/hello.sh
chmod u+x scripts/hello.sh
./scripts/hello.sh

Check:

  • Both runs print Hello, Explorer! and your current directory.
  • bash file asks Bash to read the script.
  • ./file executes it directly and needs execute permission.
  • chmod u+x adds execute permission for the owner only.

Your turn:

  1. Change the name and run again.
  2. Move into notes and run ../scripts/hello.sh.
  3. Explain whether pwd reports the caller’s directory or the script’s directory.
Check your answer and common errors

  • pwd: reports the caller’s directory.

  • PATH: lists where the shell searches for bare command names.

  • ./: explicitly identifies a local file.

  • No such file: check pwd and ls; paths depend on where you start.

  • Permission denied: inspect ls -l and add owner execute permission.

  • Bad interpreter / ^M: save with Unix/LF line endings, or recreate the file in nano inside Ubuntu.

Finish without copying#

  1. Open a new terminal and find your lab.
  2. Append a note and run the script.
  3. Explain why cd ../scripts differs from cd /scripts.
  • I reached bandit3 and can explain each file-reading command.
  • curl, git, python3 and uv report versions in my learning terminal.
  • My Bash script prints my name; I can explain chmod u+x.
  • My notes contain one solved error and one command worth remembering.

Explore:

  1. Open man ls; press q to exit.
  2. Find an option and test it on your lab.
  3. If asking AI for help, share the command/error and request a hint.
  4. Verify the result yourself.

Next: Module 2: Python & uv →

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