LAB-PERM-01 - The Permission Trinity (rwx)

Part A: The Field Guide

When you run ls -l, the first block of characters tells you a lot about access.

Example:

-rw-r--r--

The pattern is:

• first character: what kind of thing this is
• next three: owner permissions
• next three: group permissions
• last three: other permissions

The first character

• - means a regular file
• d means a directory
• l means a symbolic link

The three permission letters

• r means read
• w means write
• x means execute or traverse
• - means that permission is missing

File versus directory behavior

For a file:

• r: read the contents
• w: change the contents
• x: run the file if it is executable content

For a directory:

• r: list names inside it
• w: create, rename, or remove entries inside it
• x: enter the directory or pass through it

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Part B: The Drill Deck

Terminal required: keep everything in a harmless practice area.

G

Guided Step by step - type exactly this and compare the result

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Exercise G1: Read one file permission string

1. Run ls -l /etc/passwd
2. Identify the file type character
3. Read the owner, group, and other chunks out loud
4. State what each chunk allows

Exercise G2: Read one directory permission string

1. Run ls -ld /tmp
2. Notice the leading d
3. Explain why execute on a directory means traverse, not run

Exercise G3: Build your own example

1. Run mkdir -p ~/perm_lab && cd ~/perm_lab
2. Run touch example.txt
3. Run ls -l example.txt
4. Interpret the result in plain language

S

Solo Task described, hints available - figure it out

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Exercise S1: Decode mentally

Explain these permission strings in plain language:

1. -rwxr-x---
2. drwxrwxr-x
3. -r--------

Exercise S2: Directory logic check

If a directory gives you read but not execute, what can you observe, and what can you not do? Answer in words before testing it later.

M

Mission Real scenario - no hints, combine multiple skills

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Mission M1: Explain the directory case

In your own words, explain why deleting a file depends partly on the permissions of the directory that contains it, not just the file itself.

If you can explain that clearly, the permission model is starting to become real instead of memorized.