Disks and Partitions: lsblk, fdisk, parted
See what hardware you have, how it is partitioned, and how to add a new disk to a Linux system.
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Bash Loops and Conditionals
if, for, while, case — the control flow that turns one-liners into scripts.
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Bash Variables and Quoting
How to set, read, and quote variables in bash without the classic mistakes that break scripts on filenames with spaces.
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SSH and Key-Based Authentication
SSH is how you log into every Linux server. Set up key-based auth once and you never type a password again.
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Firewalls on Linux: ufw and nftables
Open and close ports safely. ufw for the simple case, nftables for the serious case. Both built on the same kernel facility.
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DNS Resolution on Linux: dig, nslookup, resolv.conf
How Linux turns names into IP addresses, and how to debug when it goes wrong. The four tools that solve 99% of DNS problems.
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Sockets and Ports: ss Replaces netstat
See exactly what is listening on your machine and what is connected. ss is the modern netstat — faster and more powerful.
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IP and Routing: The ip Command
The modern ip command replaces ifconfig and route. One tool to inspect addresses, links, routes, and ARP.
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pacman: The Arch Linux Package Manager
pacman is fast, minimal, and slightly cryptic. Once you memorize the flag combinations, it is the cleanest package manager out there.
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dnf: The Fedora and Red Hat Package Manager
dnf is the package manager on Fedora, RHEL, Rocky, Alma, and CentOS. Modern, fast, and increasingly capable.