Stage 4 · Lesson 2 of 8

Users, groups, root and sudo

is built for many on one machine. Each user has an ID number and belongs to one or more ; id shows yours. The root user, also called the superuser, can do anything.

So you work as a normal user and put sudo in front of single commands that need more power, such as installing packages. chown changes who owns a file. You usually need it after creating something with sudo by mistake. Adding a user to a group, such as docker, gives them that group's access.

Common traprunning everything with sudo, including npm install or commands, which leaves root-owned files in your home that later fail with "permission denied".

A question to check yourself, an AI practice session and 2 cheat sheet entries come when you add the roadmap to your account. Add it

Resources for this stage

Start with

BookFree
The Linux Command Line
William Shotts · Beginner
Its chapters on permissions and processes are the clearest free explanation of this stage

Practise

OverTheWire: Bandit
Later levels need permissions, setuid binaries and processes to progress

Keep handy

nvm (Node Version Manager)
The official README for installing nvm and switching Node versions per project
Homebrew
How brew installs, upgrades and cleans up the tools on your Mac

Also worth your time

roadmap.sh: LinuxGo deeper
See the users, permissions and process management branches of the Linux map