What you will learn
- Create and manage users
- Understand the sudoers model
- Apply least privilege
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The basics, in plain English
A Linux machine can be shared by many people and programs. Each one logs in as a "user" with its own name and its own limits. This keeps things organized and safe, so one account cannot accidentally wreck everything.
- User
- An account on the machine, with a name and its own files and permissions.
- Root
- The all-powerful admin account that can do absolutely anything. Powerful and dangerous.
- Group
- A label that bundles several users together so they can share access.
- sudo
- A command that lets a normal user run one command as the admin, after proving they are allowed.
- Least privilege
- The safety rule of giving each account only the access it truly needs and nothing more.
01
Identity
Users live in /etc/passwd, groups in /etc/group. useradd and usermod manage them. The principle of least privilege says: grant only what is needed.
02
sudo
sudo runs commands as another user, typically root. /etc/sudoers (edited with visudo) controls who can do what.
Try it yourself
bash
$useradd -m -s /bin/bash deploy↳Create a “deploy” user with a home directory and the bash shell.$usermod -aG docker deploy↳Add that user to the docker group so it can run containers.$visudo↳Safely edit the sudoers file to grant admin rights.$id deploy↳Show the user’s ID and group memberships to confirm.↳ lines explain what each command does — only the commands get copied
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