NOTES AFTER HOURS
Practical notes on Linux, small servers, and the web, plus short pieces from after hours.
Nginx Location Matching in the Order That Matters
Predict which Nginx location block will handle a request by learning how exact, prefix, and regex matches are chosen.
RDB, AOF, Both, or Neither: Redis Persistence on a Small Server
Decide whether a small Redis needs RDB snapshots, an append-only file, both, or no persistence, check that saves are really happening, and prove a restore with a throwaway instance.
Disabling IPv6 on a Linux Server, and When Not To
Decide whether disabling IPv6 actually solves your problem, then do it with a sysctl drop-in or the ipv6.disable=1 kernel parameter on Debian, Ubuntu, Rocky Linux, or AlmaLinux, verify the result, and roll it back.
Git Reflog After the Wrong Reset
Recover a local commit after an accidental reset by inspecting the reflog before moving another reference.
The Rain Started After I Ordered Ice Cream
A sudden downpour squeezes five strangers under one narrow awning, where a single cup of mango ice cream gets passed down the line.
The Cat Who Attended the Video Meeting
A cat joins a video meeting, gains decision-making authority, and leaves before anyone can assign follow-up work.
The First Hour on a Fresh Debian or Ubuntu VPS
Set up a sudo user, SSH keys, an sshd drop-in that blocks password and root logins, a ufw firewall, and automatic security updates on a new Debian or Ubuntu server, checking each step as you go.
A Small HTTP Header Check with curl
Inspect the headers a real GET request receives, follow redirects deliberately, and keep response bodies out of the terminal.
Measure an HTTP Request with curl Without Guessing
Find out which part of a slow HTTP request is slow, from DNS and TLS to the server's first byte, using curl's timing variables.
The Balcony Light Across the Street
A balcony light across the street becomes an accidental evening clock, until a moving truck reveals where the light was really coming from.
PostgreSQL Memory Settings on a Small VPS
Check and size sharedbuffers, effectivecachesize, workmem, maintenanceworkmem, and maxconnections on a small server, apply them with the right reload or restart, and confirm the effect.
A Wake-Up Call for Room 508
A 4:30 a.m. wake-up call meant for Room 508 keeps finding its way to Room 805 instead.