M3 — Paths, directories, and listing

Module brief#

Master “where am I?” and “how do I point at a file?” Absolute vs relative paths, confident cd, and the ls flags you will use every day.

Learning objectives#

• Print the working directory with pwd
• Choose absolute or relative paths appropriately
• Move around with cd, ., .., and /
• List directories using ls, -l, -a, -i, -ld, -R, -F
• Identify file kinds with ls -F and file

1. Working directory and pwd#

The shell always has a current working directory. Commands that take a relative path start from here.

pwd

/tmp/linux-lab-pushpjeet

If you ever feel lost: run pwd, then ls.

2. Absolute vs relative paths#

An absolute path starts at / and names every step:

/tmp/linux-lab-pushpjeet/notes.txt

A relative path starts from your current directory:

notes.txt
./notes.txt
project/src
../linux-lab-pushpjeet/notes.txt

Useful shorthand:

Examples from the lab folder:

cd /tmp/linux-lab-pushpjeet
pwd
ls ./project/src
ls ../   # parent of the lab dir — often /tmp

Absolute paths are unambiguous in scripts. Relative paths are shorter while you explore.

3. Moving with cd#

cd /tmp/linux-lab-pushpjeet/project
pwd
cd ..
pwd
cd ~
pwd
cd -      # jump back to the previous directory (bash)

Tips:

• cd alone or cd ~ returns home
• Tab-completion reduces typos — press Tab after typing a unique prefix
• If cd fails with “No such file or directory,” check pwd and spelling

4. Everyday ls options#

Create a small playground if you still have the course lab dir:

cd /tmp/linux-lab-pushpjeet
ls

a.txt  b.txt  empty.dat  hard-notes  notes.txt  project  readme.txt  sample.log  soft-notes

Long listing: -l#

ls -l soft-notes notes.txt project

-rw-r--r-- 2 box box   49 Sep 26 11:04 notes.txt
drwxr-xr-x 5 box box 4096 Sep 26 11:04 project
lrwxrwxrwx 1 box box    9 Sep 26 11:04 soft-notes -> notes.txt

Hidden entries: -a#

Names starting with . are hidden from plain ls:

ls -a

.  ..  a.txt  b.txt  empty.dat  hard-notes  notes.txt  project  readme.txt  sample.log  soft-notes

. and .. always appear with -a.

Classify at a glance: -F#

ls -F

a.txt  b.txt  empty.dat  hard-notes  notes.txt  project/  readme.txt  sample.log  soft-notes@

Trailing / marks a directory; @ marks a symlink (GNU ls).

Directory itself, not contents: -ld#

ls -ld project

drwxr-xr-x 5 box box 4096 Sep 26 11:04 project

Without -d, ls -l project lists what is inside project.

Inodes: -i#

ls -i notes.txt hard-notes soft-notes

1084900 hard-notes
1084900 notes.txt
1084906 soft-notes

Same inode number means the same underlying file (hard links — Module 6).

Recursive: -R#

ls -R project

project:
data  docs  src

project/data:

project/docs:

project/src:

Combine flags freely: ls -la, ls -li, ls -lF.

5. The file command#

file notes.txt /bin/ls soft-notes project /dev/null

notes.txt:  ASCII text
/bin/ls:    ELF 64-bit LSB pie executable, x86-64, ...
soft-notes: symbolic link to notes.txt
project:    directory
/dev/null:  character special (1/3)

Use file when an extension is missing or misleading.

Practice: MCQs#

Q1. Which path is absolute?

• A) ../docs
• B) notes.txt
• C) /home/student/notes.txt
• D) ./project

Q2. You are in /tmp/linux-lab-pushpjeet/project. What does cd .. do?

• A) Goes to /
• B) Goes to /tmp/linux-lab-pushpjeet
• C) Goes to your home directory
• D) Deletes the project folder

Q3. Why use ls -ld dirname?

• A) To delete the directory
• B) To list information about the directory itself
• C) To show only empty directories
• D) To follow every symlink on the system

Q4. ls -a is useful because:

• A) It sorts by file size only
• B) It shows entries whose names start with .
• C) It disables colours permanently
• D) It prints absolute paths for every file

Q5. Two names share the same inode in ls -i. That suggests:

• A) They are on different disks always
• B) They are hard links to the same file data
• C) One of them must be a directory
• D) ls is broken

Practice: Match the columns#

Practice: Fill in the blank#

1. Print working directory: ___
2. List all files including hidden: ls ___
3. Long listing of the project directory entry itself: ls ___ project
4. Relative path to a file in the current directory: ___/notes.txt or simply notes.txt
5. Absolute path example for a lab notes file: /tmp/linux-lab-pushpjeet/___

Practice: Mini terminal challenge#

Challenge: Absolute and relative navigation#

Goal: Reach the same file two ways.

Setup:

mkdir -p /tmp/linux-lab-pushpjeet/nav/{one,two}
echo hi > /tmp/linux-lab-pushpjeet/nav/one/hello.txt

Tasks:

1. cd /tmp/linux-lab-pushpjeet/nav/two
2. Display the file using a relative path with ..
3. Display it again with an absolute path
4. Run ls -F .. and confirm one/ appears

Verify: Both cat commands print hi.

Stretch: From nav/two, use cd only with relative paths to land in nav/one, then pwd.

Hands-on lab#

Goal: Fluent navigation and listing.

Steps:

1. From your home directory, cd into the lab folder using an absolute path; pwd.
2. cd into project/docs using a relative path; pwd.
3. Compare ls, ls -l, ls -la, and ls -lF on the lab root — note differences in your notes.
4. Run file on one text file and one binary (/bin/ls or $(which ls)).

Verify: Your notes include one absolute and one relative path that both refer to the same file.

Stretch: Use ls -R on a small tree and redraw it as an indented outline by hand.

Common mistakes#

• Mixing up ls project (contents) with ls -ld project (the directory itself)
• Forgetting that relative paths depend on pwd
• Typing spaces in paths without quoting (Module 9 covers quoting; for now avoid spaces in lab names)
• Assuming ~ works inside every program the same way — the shell expands it before most commands run

Summary#

You can locate yourself with pwd, speak in absolute or relative paths, move with cd, and read rich directory listings. That navigation skill is the foundation for viewing and changing files next.

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