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Engineering Notes That Still Have Something to Teach

These guides begin with real implementation problems from the Linux Heart archive: an SSH session that stopped responding, a database connection that failed, or a cache that moved the bottleneck instead of removing it.

The original experience remains part of each article. The November 2026 follow-ups explain what a reader can take from it, distinguish an observation from a general diagnosis, and point to the relevant documentation. They are documentation reviews and worked examples, not claims that the original production incidents were rerun.

Adding a watermark to a video with FFMPEG

Replace the old vhook command with an overlay filter, with explicit stream mapping and a separate output file.

First published May 23, 2009 · Follow-up added November 14, 2026

Reading an old debugging story

Start with the environment and symptom, then separate what was measured from what was suspected. An old package name, command or framework implementation may no longer apply. Where the original note ends with an unresolved hypothesis, the follow-up says so.

The full archive also keeps shorter historical notes and personal writing. For the current business side of building software, see the product and marketing journal.