A command you're told to run, with no hint why

Create an empty repo and GitHub hands you a block to paste, including:

git branch -M main

If your Git is modern and configured, init.defaultBranch is already main — so this line renames main to main. It does nothing. But nothing on the page says when it’s needed, so you either stop and work it out, or paste on faith and learn nothing.

GitHub’s side of it — which is good

This one deserves its steelman up front, because the obvious complaint is wrong. GitHub cannot see your local Git config. Git’s built-in default is still master (2.28 added init.defaultBranch but kept the old fallback for compatibility), while GitHub names its own repos main. So a snippet that omitted the rename would break for everyone on an unconfigured Git, and -M is harmless when there’s nothing to rename. The defensive line is correct engineering.

The paper-cut isn’t the command. It’s the missing “why”.

The principle

When you instruct someone to run something whose necessity depends on state you can’t see, say so. One clause — “if your Git still defaults to master” — converts an unexplained ritual into a conditional the reader can evaluate. Without it you get two costs: the people who stop to reason it out, and the people who paste blindly and never learn what their own tooling does.

There’s a third, costlier path: someone skips the line, ends up with a local master pushed against a GitHub main, and spends minutes untangling two branches that should have been one.

The math

~121M new repos/yr × CLI paste path × confusion & mismatch = ≈0.05 lifetimes / year

The second micro case on this site, and deliberately so. Like case 012, it’s far too small to move the total — real cost, negligible scale. Documenting it is only worth anything because the arithmetic says it’s negligible: that’s the difference between a metric and a complaint.

Difficulty to fix: none

The command is right. The silence around it isn’t. Add the condition it depends on — six words — and the ritual becomes knowledge.