Where you are

02Home is an anchor

An absolute path begins with / and starts at the root directory, the top of the Linux path tree. A relative path begins from the current working directory. From /home/desk/lab, notes means /home/desk/lab/notes. A leading slash changes its meaning: /notes names a location directly under root.

The short path . means the current directory; .. means its parent. cd notes enters a child named notes. cd .. moves to the parent. Check pwd after either action so your next command starts where you intend.

Bash expands ~ at the start of an unquoted path to your home directory. cd with no argument also returns home. Home is usually a personal directory; / is the filesystem root. The root directory is different from the root administrator account.

mkdir creates a directory. Plain mkdir reports a conflict when the requested name already exists. Here that tells you to preserve earlier work. Enter one command at a time and continue only after it succeeds. If a destination exists, choose a new name consistently or use the printed tree.

/home/desk/lab

03Try a new navigation tree

The worksheet separates an example tree from the question at the end. In the activity, make only the small navigation tree under your own lab directory. Its named folders are enough to practice cd and pwd; you do not need to download an archive.

For the paper route, start at /home/desk/yanosec-lab/navigation. Draw desk-demo with children notes and receipts, then follow the same moves in the numbered steps. Write the complete working path after each move. Creating folders and checking them in a terminal can wait.

Path practice and complete archive inventory

Read this tree before navigating. The archive contains only the files
listed below. For paper practice, begin in the stated activity directory
and record the working path after entering notes and after cd ..

This is a complete printed inventory, not an extraction record.
desk-demo/
  notes/map.txt = route north (newline)
  receipts/item.txt = pencil (newline)
Example working directory: /home/desk/lab
Example action: cd notes -> predicted /home/desk/lab/notes
Activity: navigate desk-demo/notes then cd .. back to desk-demo.
Question current directory: /home/desk/tasks
Question child directory: receipts
Question action: cd receipts
Record the resulting absolute path, not the activity's real home path.

1. Use cd with no argument, then pwd. If ~/yanosec-lab is absent, create it with mkdir ~/yanosec-lab. If it already exists, inspect it and use it only when you recognize it as your owned lab; otherwise stop and choose a fresh root name consistently or the paper route.
2. Enter cd ~/yanosec-lab. Create a new child with mkdir navigation, then cd navigation. If mkdir reports a conflict, stop rather than entering an existing unknown destination.
3. Create a small tree: mkdir desk-demo, then mkdir desk-demo/notes and mkdir desk-demo/receipts. These create directories only; the optional archive additionally supplies the ordinary data files listed in tree.txt.
4. Enter cd desk-demo, inspect pwd, then cd notes and pwd. Expected: the working path ends in /navigation/desk-demo/notes. Enter cd .. and inspect pwd again; it ends in /navigation/desk-demo.
5. Compare these observed suffixes with the fictional example, not with its username. Return using cd ~/yanosec-lab. Retain the tiny tree for later review; no deletion is required.

04An optional archive route

An archive is one file that bundles other files and directories. The optional desk-demo.tar.gz also contains the ordinary data files printed in the worksheet. Read the archive guide before using tar, the program that lists or extracts its entries.

List the archive first and compare every path with the supplied inventory. Extract means write those entries back into directories. Use a new empty destination so extraction cannot replace earlier work. The activity above already practices navigation without extraction.

Read an owned archive before extracting it

An archive bundles named entries. Extracting writes those entries back
to disk. A .tar.gz file uses tar bundling plus gzip compression; neither
operation encrypts the content. Use only the supplied owned archives.

All supplied archives contain original ordinary text files under one
named directory. No symlinks, executables with special modes, devices,
absolute paths or parent traversal entries are authored. Inspect first.
Save the chosen archive in the GUEST Downloads folder. If its actual
location differs, use that quoted absolute path; do not guess.
Use a new destination beneath ~/yanosec-lab, never an existing folder.
Example templates (replace ARCHIVE.tar.gz and NEW-DEST):
tar -tzf ~/Downloads/ARCHIVE.tar.gz
mkdir ~/yanosec-lab/NEW-DEST
tar -xzf ~/Downloads/ARCHIVE.tar.gz -C ~/yanosec-lab/NEW-DEST
Run the extraction only if mkdir succeeded and inventory matches.
t lists; x extracts; z handles gzip; f names archive; -C names target.
Keep original data; do not use sudo, overwrite flags or root extraction.
Stop on an unexpected path/link/member or download you cannot identify.
Fallback: read the full inline tree and contents; predict actions in notes.
Cleanup: leave scoped files for review; restore a guest baseline only
if all subsequent guest work is disposable. No broad rm command.

05Optional challenge

Allow about ten extra minutes. Starting at /home/mila/projects/drafts on paper, compare cd .. with cd /home/mila. The first uses the current location; the second names a destination from root. Explain both resulting paths before checking them against your drawing.

06Fresh cases for the checks

Use these fictional cases for the checks below. They have different inputs from the worked examples. Read them here or make notes; no installation or external service is needed.

Starting directory: /home/nila/Field
Its child directories are Maps and Reports. Reports contains a child named Final.
Commands, in order: cd Maps; cd ..; cd Reports; cd Final; cd ..
Each listed command succeeds. No symbolic links are involved.

Starting directory: /home/teo/Projects
Two existing directories: /home/teo/Projects/Archive and /Archive
The learner intends to enter the Archive inside Projects.
Consider cd Archive, cd /Archive and cd .. independently from the same starting directory.
Names and capitals are exact; no symbolic links are involved.

Current directory: /home/ines/owned-lab
Goal: create a NEW empty directory for a file-writing exercise.
Command attempted: mkdir review
Supplied result: creation failed because review already exists.
The contents of review have not been inspected or identified as disposable.

Account home directory: /home/omar
Current directory: /home/omar/lab/notes
Next command: cd
The command has no argument and succeeds in the stated Bash environment.

07Explain how you would confirm a destination

Optional self-check: explain why a successful cd does not by itself prove that you reached the directory you intended. Add what you would do when an exercise directory already exists.

Review your explanation: distinguish absolute and relative paths, use pwd to check the full location, preserve exact name capitalization, and stop before writing into an unknown existing destination. This explanation is self-reviewed.