Namespaces and cgroups: How Containers Actually Work
Containers are not VMs. They are regular Linux processes wrapped in two kernel features. Understand them and Docker stops being magic.
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SSH Hardening: Lock Down Remote Access
Disable root login, require keys, change the port, add fail2ban. The five-minute checklist that stops 99% of SSH attacks.
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LVM: Resize and Snapshot Live Filesystems
LVM lets you grow filesystems online, take snapshots, and pool multiple disks. The plumbing every serious Linux server uses.
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Mounting and fstab: Make Filesystems Available
mount and /etc/fstab control which filesystems are available where. Master fstab and your disks come up correctly every boot.
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Debugging Bash Scripts: set -x, set -e, traps
Three flags and a trap. The minimum tooling that turns “why is this script broken?” into “I see what happened.”
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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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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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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.