Lab 03: Directory Navigation

Objective

Move around the Linux filesystem with confidence: cd, ls, absolute vs relative paths, tab completion, and navigation shortcuts. You'll create a realistic project structure and navigate it fluently.

Time: 25 minutes | Level: Foundations | Docker: docker run -it --rm ubuntu:22.04 bash

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Step 1: Your Starting Position

pwd

📸 Verified Output:

/

cd ~
pwd

📸 Verified Output:

/root

💡 ~ (tilde) is a shortcut for your home directory. cd ~ always brings you home no matter where you are — like pressing the home button on your phone.

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Step 2: Exploring Your Home

ls -la

📸 Verified Output:

total 16
drwx------ 2 root root 4096 Feb 10 14:12 .
drwxr-xr-x 1 root root 4096 Mar  5 00:54 ..
-rw-r--r-- 1 root root 3106 Oct 15  2021 .bashrc
-rw-r--r-- 1 root root  161 Jul  9  2019 .profile

💡 . = current directory. .. = parent directory. Files starting with . are hidden — only visible with ls -a. .bashrc and .profile are shell startup scripts.

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Step 3: Create a Project Structure

mkdir -p projects/webapp/src
mkdir -p projects/webapp/tests
mkdir -p projects/scripts

ls -R projects/

📸 Verified Output:

projects/:
scripts  webapp

projects/scripts:

projects/webapp:
src  tests

projects/webapp/src:

projects/webapp/tests:

💡 mkdir -p creates all intermediate directories at once. Without -p, mkdir projects/webapp/src would fail if projects/ doesn't exist yet.

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Step 4: Absolute vs Relative Paths

Absolute path — always starts with /, works from anywhere:

cd /tmp/projects 2>/dev/null || { mkdir -p /tmp/projects/webapp/src /tmp/projects/scripts && cd /tmp/projects; }
pwd

📸 Verified Output:

/tmp/projects

Relative path — relative to where you currently are:

cd webapp
pwd

📸 Verified Output:

/tmp/projects/webapp

cd ../..
pwd

📸 Verified Output:

/tmp

💡 .. goes up one level in the directory tree. ../../ goes up two levels. ../sibling goes up one then into sibling — without ever needing to know the full absolute path.

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Step 5: Navigation Shortcuts

# Go somewhere
cd /etc

# Jump back to where you just were
cd -
pwd

📸 Verified Output:

/etc
/tmp

# Jump to home instantly
cd
pwd

📸 Verified Output:

/root

💡 cd - is like the "back" button in a browser — instantly returns to your previous directory. Extremely useful when switching between two distant directories.

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Step 6: Listing Options

cd /etc

# Long format with human-readable sizes
ls -lh | head -8

📸 Verified Output:

total 280K
drwxr-xr-x 1 root root 4.0K Feb 10 14:05 .
drwxr-xr-x 1 root root 4.0K Mar  5 00:54 ..
-rw------- 1 root root    0 Feb 10 14:05 .pwd.lock
-rw-r--r-- 1 root root 3.0K Feb 10 14:05 adduser.conf
drwxr-xr-x 2 root root 4.0K Feb 10 14:11 alternatives
drwxr-xr-x 8 root root 4.0K Feb 10 14:05 apt
-rw-r--r-- 1 root root 2.3K Jan  6  2022 bash.bashrc

# Only subdirectories
ls -d */

📸 Verified Output:

alternatives/  apt/  cloud/  cron.d/  cron.daily/  ...

# Sort by modification time, newest first
ls -lt | head -5

📸 Verified Output:

total 280
drwxr-xr-x 8 root root  4096 Feb 10 14:05 apt
drwxr-xr-x 2 root root  4096 Feb 10 14:11 alternatives
drwxr-xr-x 1 root root  4096 Mar  5 00:54 .

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Step 7: Traverse the Filesystem

# Navigate deep into usr
cd /usr/share/doc
ls | wc -l

📸 Verified Output:

28

# Go up two levels using relative path
cd ../..
pwd

📸 Verified Output:

/usr

# Cross from usr to etc using absolute path
cd /etc
# Cross to var using relative
cd ../var
pwd

📸 Verified Output:

/var

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Step 8: Capstone — Navigate a Security Lab Structure

# Build a realistic security lab directory
mkdir -p ~/security-lab/{recon,exploitation,post-exploit,reporting,tools}
mkdir -p ~/security-lab/recon/{nmap,web,dns}
mkdir -p ~/security-lab/exploitation/{payloads,scripts}

# Navigate and inspect
cd ~/security-lab
ls -R

# Practice: go to nmap folder using relative path from security-lab
cd recon/nmap && pwd

# Come back with one command
cd ~/security-lab && pwd

# Go to payloads using a mix
cd exploitation/payloads && pwd
cd ../../reporting && pwd

📸 Verified Output:

/root/security-lab/recon/nmap
/root/security-lab
/root/security-lab/exploitation/payloads
/root/security-lab/reporting

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Summary

Command / Shortcut	Meaning
cd ~ or cd	Go to home directory
cd -	Return to previous directory
cd ..	Go up one level
cd ../..	Go up two levels
pwd	Print current directory
ls -la	List all files with details
ls -lh	List with human-readable sizes
ls -lt	List sorted by modification time
mkdir -p a/b/c	Create nested directories at once