The check that cannot fail, and the flush that proves nothing
gzip -t passes on an empty archive and a cache flush returns the same wrong answer: the two halves of the question to ask before choosing a command.
18 minutesTechnical content last reviewed on 3 Aug 2026
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What this lesson builds
- Saying what an output proves, and what it leaves open
- Designing a check that can fail and an alert somebody acts on