Linux Package Management with apt and dnf — Like an Admin
Use apt and dnf like production ops: updates, holds, repos, cleanup, and “what changed?” — not student homework installs.
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systemd for New Admins: Services You’ll Actually Touch at Work
systemd units, journals, restarts, and timers the way junior admins meet them on the job — practical, not encyclopedia.
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Bash Scripting for Sysadmins (Not Hackers)
Practical Bash for ops automation: readable scripts, safe defaults, exit codes, and habits that survive 2 AM — not CTF cleverness.
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Bash Logging and Error Handling for 2 AM Ops
set -euo pipefail, traps, and logs that help at 2 AM — practical Bash error handling for sysadmins.
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Parse Logs Like an Admin: grep, awk, and sed on Real Shapes
Practical grep, awk, and sed for sysadmins on real log shapes — nginx, auth, journal — without one-liner worship.
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Schedule and Wrap Cron Jobs Safely (Bash Ops)
Wrap Bash scripts for cron with locks, PATH, logs, timeouts, and exit codes — so night jobs stay boring.
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SSL Certificate Expired: Emergency Fix + How to Never Miss Renewal
Browser screaming certificate expired? Renew Let’s Encrypt or replace the cert, reload the proxy, and set monitoring so this never ambushes you again.
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Linux OOM Killer: Why Your Process Died and How to Stop the Next One
Process vanished? Kernel OOM killer likely shot it. Read dmesg/journal, score victims, and fix memory pressure without cargo-cult swap.
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MySQL/MariaDB Connection Refused: Checklist That Fixes It
Can’t connect to MySQL/MariaDB? Connection refused means nothing accepted the TCP handshake. Check listen address, socket, service, and firewall in order.
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SELinux Permission Denied: Read AVC Denials Without Rage-Quitting
SELinux saying permission denied? Read AVC denials with ausearch/journalctl, fix contexts or booleans — don’t just setenforce 0 and pray.
