Linux

cert.crt, chain_cert.crt, root_cert.crt and a .key. I’d installed them a dozen times without knowing why there were four, so I finally sat down and worked it out on my own server.

Running dev and prod side by side on one AWS box. Compose project names fixed the collisions, and made it really easy to forget everything Docker doesn’t own.

Answering a marketing question with grep and awk on nginx access logs: requests vs. visitors, bots, timezones, and why the log can’t tell you what the browser never sent.

A small C debugger that single-steps a program, rewrites its registers and memory, and changes what it does. Then figuring out why real debuggers don’t work like that — a breakpoint is literally one byte, 0xCC.