sudo Command in Linux: Run as Another User

Quick take: The sudo command runs a single command with elevated (usually root) privileges: sudo apt update. Use sudo -i for a root shell and sudo -u user to run as a specific user. Permissions are defined in the sudoers file.

Introduction

The sudo command (superuser do) lets a permitted user run a command as root or another user, without logging in as that user. It is the cornerstone of safe Linux administration: instead of staying logged in as all-powerful root, you grant elevated rights only for the specific commands that need them.

This guide covers running commands as root and other users, getting a root shell, and editing the sudoers configuration safely.

Syntax

The basic syntax of the sudo command is:

sudo [OPTIONS] COMMAND

Granting sudo Access Safely

Who may use sudo, and for what, is defined in /etc/sudoers and files under /etc/sudoers.d/. Never edit these with a plain editor — always use visudo, which validates the syntax before saving and prevents a mistake from locking everyone out of admin rights.

# Add a user to the sudo group (Ubuntu/Debian)
sudo usermod -aG sudo alice

# Grant a user one specific command without a password (via visudo)
alice ALL=(ALL) NOPASSWD: /usr/bin/systemctl restart nginx

The least-privilege principle applies: grant the narrowest rights that get the job done, rather than blanket root access.

Common Options and Parameters

The most useful options and parameters for the sudo command:

Practical Examples

Real sudo commands you can run today:

# Run a command as root
sudo apt update
# Rerun the previous command with sudo
sudo !!
# Open a root shell
sudo -i
# Run a command as another user
sudo -u www-data php artisan queue:work
# See what you are allowed to run
sudo -l
# Edit the sudoers file safely
sudo visudo

Tips and Best Practices

• sudo !! reruns your last command with sudo — the classic fix right after a “permission denied”.
• Prefer sudo command over a permanent root shell so each elevated action is deliberate and logged.
• Always use visudo to edit sudoers; a syntax error edited directly can lock you out of sudo entirely.

Final Thoughts

sudo is what makes day-to-day Linux administration both possible and safe — elevating privileges only for the command that needs them, with every use logged. Learn -i for a root shell, -u to act as another user, and always edit sudoers with visudo. Used with the least-privilege mindset, it keeps systems secure and auditable.