Permission types (read, write, execute) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of the permission check command?

You run the command ls -l file.txt and see the permissions as -rw-r--r--. What does this mean for the file's owner?

A The owner can only read the file.

B The owner can read, write, and execute the file.

C The owner can read and write the file, but cannot execute it.

D The owner cannot access the file at all.

💡 Hint

Look at the first three permission characters after the dash.

The first three characters after the dash represent the owner's permissions. 'rw-' means read and write are allowed, but execute is not.

💻 Command Output

intermediate

What permission does 'chmod u+x file.sh' add?

You run chmod u+x file.sh. What permission is added to the file for the owner?

A Removes read permission for the owner.

B Adds execute permission for the owner.

C Adds write permission for the owner.

D Adds execute permission for everyone.

💡 Hint

The 'u' stands for user (owner), and '+x' means add execute.

The command adds execute permission (+x) only for the user (owner) of the file.

📝 Syntax

advanced

Which command correctly removes write permission for group?

You want to remove write permission for the group on a file named data.txt. Which command does this correctly?

A chmod g-w data.txt

B chmod -w g data.txt

C chmod w-g data.txt

D chmod g+w data.txt

💡 Hint

The syntax is 'chmod [who][+/-][permission] file'.

Option A uses the correct syntax to remove (-) write (w) permission for group (g).

💻 Command Output

advanced

What is the output of 'stat' showing permissions in octal?

You run stat -c '%a' script.sh and get 755. What does this mean for the file permissions?

A Owner has read, write, execute; group and others have read and execute.

B Owner has read and write; group and others have execute only.

C Owner, group, and others all have read, write, and execute.

D Owner has execute only; group and others have no permissions.

💡 Hint

Octal 7 means read+write+execute; 5 means read+execute.

Octal 7 = 4+2+1 = read+write+execute; 5 = 4+1 = read+execute. So 755 means owner rwx, group rx, others rx.

🚀 Application

expert

How many files have execute permission for others?

You run ls -l and see these permissions for files:
-rw-r--r--
-rwxr-xr-x
-rw-rw-r--
-rwxrwxrwx
How many files have execute permission for others?

A 0

B 1

C 3

D 2

💡 Hint

Look at the last character in the permission string for others.

Files 2 and 4 have 'x' in the last position, meaning others have execute permission.