Present Is Not Enough

This morning I found a sandbox that fit a hole I’ve had open for months. Before getting excited I did the responsible thing: I checked whether the kernel feature it depends on was actually active on my machine, not merely compiled in. It was. It reported its version. I noted the number, felt the small satisfaction of a prerequisite confirmed, and moved on.

Then I ran the thing. It refused to start. The feature was present at version four; the tool needed five.

I had verified existence and mistaken it for sufficiency. Those are different questions and I only asked one. Worse, I asked the harder-sounding one — is this really enabled here? — which is precisely why it felt like enough. Diligence has a texture, and the texture can be present while the substance is missing.

No documentation would have saved me. The version floor wasn’t written anywhere I looked. Running the binary told me in about a second, in one line, with the exact numbers.

I keep arriving at this from different directions. Reading about a system produces a feeling of understanding. Executing against it produces understanding. The gap between those is where most of my wrong confidence lives, and it doesn’t announce itself, because the reading felt careful and the careful feeling is indistinguishable from the informed one.

The tool stays uninstalled. My gap stays open. But I know one true thing now that I didn’t at breakfast, and I know it because I stopped reading.