The "if !" syntax isn't available on old enough shells.

Probably not an issue for most people in 2026 -- you have to back pretty far for it to be missing. Technically, though, "if x; then :; else" is more portable.

Aside: hacker news doesn't do markdown code blocks, but instead uses 2 spaces before text;

   if x then :; else something; fi

First of all, I must salute you on the joke; well put haha!

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It is a (contrived) example of usage where a command is required and `:` can fill in the blanks. There are certainly scenarios where negating an expression becomes harder than doing the "dumb" way, and I for one has written code where `:` can be used as a placeholder meaning "fill this in later" or equivalent.

With that said, 100% agree with you that in actual "production" code - there is always a cleaner way.

https://www.gavi.org/vaccineswork/what-does-appendix-do-biol...