# Linux cheat sheets: essentials, systemd, networking

> Five verified Linux cheat sheets: essential commands, systemd services, iproute2 networking, disks and LVM, and file permissions.

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# Linux cheat sheets

These five sheets cover the Linux a sysadmin actually types. [Essential commands](https://itinsighthub.com/linux/essential-commands/) is the daily driver: navigation, reading logs, grep and text reshaping, tar, processes and packages. [systemd services](https://itinsighthub.com/linux/systemd-services/) pairs every systemctl verb with the journalctl query that explains what the service did. [Networking](https://itinsighthub.com/linux/linux-networking/) is built entirely on the modern iproute2 stack — `ip` and `ss` — plus dig, curl, NetworkManager and both firewall families.

The remaining two finish the picture: [disks & storage](https://itinsighthub.com/linux/disk-and-storage/) runs from `df -h` triage through fstab and SMART to a compact LVM reference, and [permissions & ownership](https://itinsighthub.com/linux/permissions-ownership/) decodes numeric chmod, umask, the special bits and ACLs with honest security notes. Everything assumes a current mainstream distro — Debian 12+, Ubuntu 22.04+, RHEL 9 / Rocky / Alma / Fedora — with systemd 250+, GNU coreutils and iproute2. Where Debian-family and Red Hat-family differ (packages, firewalls), the row says which is which.

## Cheat sheets

### Essential commands

Navigate, read, search, archive and manage processes — the 40-plus commands behind every Linux session

### systemd services

systemctl control verbs, unit overrides and journalctl log queries — including masking, editing and journal disk limits

### Networking

ip and ss from iproute2, dig and curl, NetworkManager profiles, hostnamectl, plus ufw and firewalld one-liners

### Disks & storage

df and du capacity triage, lsblk and mounting, fstab done safely, SMART health, TRIM, careful dd and a compact LVM path

### Permissions

Numeric and symbolic chmod decoded, chown patterns, umask math, SUID/SGID/sticky with security notes, and setfacl ACLs

## Network tools

[Subnet Calculator](https://itinsighthub.com/subnet-calculator/)[IPv6 Calculator](https://itinsighthub.com/ipv6-subnet-calculator/)[Wildcard Mask](https://itinsighthub.com/wildcard-mask-calculator/)[Range → CIDR](https://itinsighthub.com/ip-range-to-cidr/)[Splitter](https://itinsighthub.com/subnet-splitter/)[Aggregator](https://itinsighthub.com/cidr-aggregator/)[VLSM Calculator](https://itinsighthub.com/vlsm-calculator/)[Practice](https://itinsighthub.com/subnetting-practice/)[Cheat Sheet](https://itinsighthub.com/subnet-cheat-sheet/)

## FAQ

**Which Linux distributions do these cheat sheets assume?**

Current mainstream releases: Debian 12+, Ubuntu 22.04/24.04, Fedora, and the RHEL 9 family (RHEL, Rocky, Alma). Everything assumes systemd 250+, GNU coreutils, util-linux and iproute2 — the stack those distros ship. The genuine divergence points are called out inline: package management (apt vs dnf) and firewalls (ufw vs firewalld) carry per-family rows.

**What replaced netstat and ifconfig on Linux?**

iproute2: ss replaces netstat (ss -tulpn is the listening-ports-with-processes audit) and ip replaces ifconfig (ip addr), route (ip route show) and arp (ip neigh). The legacy net-tools binaries are unmaintained, miss modern kernel features and are no longer preinstalled on mainstream distros. The networking sheet includes a full translation table.

**Do I need root (sudo) for these commands?**

Inventory reads generally do not: ls, cat, grep, ps, df, du, ip addr, ss, systemctl status, journalctl (if you are in the systemd-journal/adm/wheel group), stat and getfacl all run as a normal user. State changes do: installing packages, systemctl start/stop/enable/mask, ip address changes, mount, dd, chmod/chown on files you do not own, firewall rules and fstrim. Rows needing root carry sudo in the sheet itself.

**I am new to Linux administration — which sheet first?**

Start with the essential commands sheet until navigation, grep and process handling are reflexes, then move to systemd services — managing units and reading journals is the daily rhythm of a Linux admin. Networking and disks slot in as your responsibilities grow, and the permissions sheet doubles as a reference you revisit whenever an access question appears. Each sheet is self-contained and cross-linked.

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