Linux-Commands

Author

K19G

Published

July 31, 2026

Updated

July 31, 2026

Linux Commands Reference

A practical, Ubuntu-first command encyclopedia for daily administration, scripting, and troubleshooting.

Each chapter covers one command (or a tight family): syntax, important options, realistic examples, output notes, safety tips where it matters, and related tools.

How to use this book

  1. Browse by part in the sidebar (files, processes, networking, packages, …).
  2. Search for a command name when you already know what you need.
  3. Prefer worked examples over option dumps — copy, adapt, verify.
  4. For shell programming (functions, arrays, set -euo pipefail), see Linux-ShellScripting-Bash in this monorepo.
  5. For containers, editors, and homelab design, use the sibling books — this one stays on the CLI surface.

Page template

Most pages follow this shape:

  1. Overview
  2. Syntax
  3. Common options
  4. Key use cases
  5. Examples with explanations
  6. Understanding output (when useful)
  7. Common patterns / pitfalls
  8. Related commands
  9. Further reading

Short utilities may use a lighter form (overview + examples + related).

Parts at a glance

Part Focus
Help and docs man, info, help, apropos, whatis
Files and paths Navigation, copy/move, permissions, search (find, locate)
Archives and compression tar, gzip, xz, zstd, zip family
System information Host identity, memory, users online, hardware summaries
Processes and jobs ps, top, signals, job control, priority
System monitoring iostat, vmstat, sar, mpstat
Users and groups Accounts, passwords, aging
Networking ip, ss, DNS, SSH, transfer, firewalls, capture
Scheduling cron, crontab, at, anacron
Logging logger, logrotate (see also journalctl)
Hardware lshw, lspci, dmidecode, hdparm
Storage and filesystems lsblk, mount, mkfs, fsck, …
Terminals and mux tmux, screen, and friends
Text and pipes grep, sed, awk, jq, sort/uniq pipelines
Packages apt/dpkg, dnf/rpm, yum
Services and runtime systemctl, journalctl, reboot/shutdown
Printing CUPS client (lp, …)
Appendices Cheatsheets and longer extras

Conventions

  • Examples assume a modern GNU/Linux userland (Ubuntu 22.04/24.04 compatible unless noted).
  • Prefer ip / ss / systemctl over legacy ifconfig / netstat / SysV-only workflows.
  • Destructive commands include safety notes (rm, mkfs, dd-style operations, firewall changes).
  • “Related commands” point to other chapters in this book when they exist.

Suggested learning paths

New to the shell

  1. Help and docs → Files and paths (ls, cd, cp, mv, rm, chmod)
  2. Text and pipes (cat, less, grep, head/tail)
  3. Processes (ps, top, job control)

Day-2 operator

  1. Services (systemctl, journalctl)
  2. Networking (ip, ss, ping, curl, ssh)
  3. Packages (apt) and storage (df, du, lsblk)

Troubleshooter

  1. Monitoring (vmstat, iostat, top)
  2. Network path (ping, traceroute, ss, tcpdump)
  3. Logs (journalctl, logrotate, logger)

Contributing shape

When adding a command page under content/<part>/:

  1. Use a lowercase filename matching the command (jq.md, zstd.md).
  2. Prefer the shared template in content/_planning/command-page-template.md.
  3. Run bash scripts/update-index.sh from this book directory.
  4. Do not hand-edit _quarto.yml.