Special permissions (setuid, setgid, sticky bit) in Linux CLI - Mini Project: Build & Apply

Understanding Special Permissions: setuid, setgid, and sticky bit

📖 Scenario: You are a system administrator managing a shared Linux server. You need to understand how special permissions like setuid, setgid, and the sticky bit work to control access and security on files and directories.

🎯 Goal: Learn how to set and verify special permissions setuid, setgid, and sticky bit on files and directories using Linux commands.

📋 What You'll Learn

Create a test file and a test directory

Set the setuid permission on the test file

Set the setgid permission on the test directory

Set the sticky bit on the test directory

Verify the special permissions using ls -l

💡 Why This Matters

🌍 Real World

System administrators use special permissions to control how users can execute files and manage shared directories securely.

💼 Career

Understanding and managing special permissions is essential for Linux system administrators and security professionals to maintain system integrity and user access control.

1

Create a test file and a test directory

Create a file called testfile and a directory called testdir using Linux commands.

Linux CLI

# Create a file named testfile
# Create a directory named testdir

Need a hint?

Use touch to create an empty file and mkdir to create a directory.

2

Set the setuid permission on the test file

Use the chmod command to set the setuid permission on the file testfile.

Linux CLI

touch testfile
mkdir testdir
# Set setuid permission on testfile

Need a hint?

Use chmod u+s filename to set the setuid bit on a file.

3

Set the setgid permission on the test directory

Use the chmod command to set the setgid permission on the directory testdir.

Linux CLI

touch testfile
mkdir testdir
chmod u+s testfile
# Set setgid permission on testdir

Need a hint?

Use chmod g+s directoryname to set the setgid bit on a directory.

4

Set the sticky bit on the test directory and verify all permissions

Use the chmod command to set the sticky bit on the directory testdir. Then use ls -l to display the permissions of testfile and testdir.

Linux CLI

touch testfile
mkdir testdir
chmod u+s testfile
chmod g+s testdir
# Set sticky bit on testdir
# List permissions of testfile and testdir

Need a hint?

Use chmod +t directoryname to set the sticky bit. Use ls -l to check permissions. Look for s in the user or group permissions and t at the end for sticky bit.