Understanding and Using su and sudo Commands in Linux

This guide explains the differences and usage of the Linux su and sudo commands for switching users and executing commands with elevated privileges.

Preparation : Create a test user with useradd -m test_user, then set its password using passwd test_user. Switch back to the original user with exit.

su command : Demonstrates non‑login shell ( su test_user) versus login shell ( su - test_user) and shows how environment variables like PWD differ. Includes examples of switching from ubuntu to root and back.

sudo command : Describes the meaning of sudo (“super user do”), how to run a command with root privileges, and shortcuts like sudo !!. Shows how /etc/sudoers controls who can use sudo, the use of visudo for safe editing, and adds test_user to the sudoers file with a line such as test_user ALL=(ALL:ALL) ALL.

Comparison : Highlights security differences between using su - (requires root password) and sudo su - (requires only the current user's password) and why sudo is preferred for controlled privilege escalation.