Introduction

This guide is a quick reference for common Linux command-line tasks. It focuses on Ubuntu and other Debian-based systems, although many commands are common across Linux distributions.

Linux commands usually follow this pattern: command [options] [arguments]. Options change how a command behaves. Short options commonly use one hyphen, such as -l, while long options commonly use two, such as --human-readable.

Administrative commands

sudo runs a command with elevated privileges. Use it only when the operation needs administrator access. A command run with sudo can modify system files, users, disks and services, so check the command before running it.

sudo commandsudo -iexit

sudo command elevates one command. sudo -i opens an interactive root login shell. exit leaves that shell.

Built-in documentation

man opens the manual page installed for a command. Manual pages normally describe syntax, every supported option, files used by the program and related commands.

man lsman -k partitioncommand --help

man ls opens the manual for ls. man -k searches manual page names and descriptions by keyword. Many commands also support --help for a shorter summary.

Press q to leave a manual page. Use /text to search inside it and n to move to the next match.

Commands and available flags can differ between distributions and versions. Check man or --help before using an unfamiliar option on an important system.