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Users & Root

Previous: Command History | Next: The Filesystem

Linux has two categories of users: root (superuser) and normal users. Knowing the difference is essential for permissions, security, and daily operations.

User Types at a Glance

User Type Home Directory UID Privileges Common Groups
root /root 0 Full, unrestricted root, wheel, sudo
Normal user /home/<username> ≥ 1000 Limited to owned files users, sudo (if granted)

Root is powerful but risky — a single mistake can break the system. Operate as a normal user for daily tasks and only escalate when necessary.

Root User

The root account has unrestricted access to all commands, files, and settings. It can modify system configuration, install or remove software, and manage other users.

  • Username: root
  • Home: /root
  • UID: 0

Root Access Groups

Different distributions use different group names for granting sudo access:

Group Used on
sudo Ubuntu, Debian
wheel Fedora, CentOS, RHEL, Arch

Users added to one of these groups can run administrative commands via sudo.

sudo — Temporary Elevation

sudo (superuser do) runs a single command with elevated privileges without switching fully to the root account. Every action is logged.

sudo apt update
sudo systemctl restart sshd

Configuration lives in /etc/sudoers. Always edit it with visudo — it validates syntax before saving:

sudo visudo

Switching Users

Command What it does
su - Switch to root (full login shell)
su <username> Switch to another user
sudo -u <username> <command> Run one command as another user
whoami Print the current user

The - in su - loads the target user's full environment (profile, PATH, etc.). Without it you keep the calling user's environment.

What to Read Next

You want to... Go here
Understand how files and directories are structured The Filesystem
Go back to history commands Command History