"A bug is every user-visible behaviour that is contrary to the documentation."

So, "no docs, no bugs" ?

I'll remember that for next time I need a good excuse for not having written documentation ;)

So, "no docs, no bugs" ?

Yes. And no.

If you try to define rigorously what a bug is, you don't really have a choice.

However normally the documentation isn't really rigorous either. The manpage for grep say it searches for matches of regular expressions - but it doesn't say that it terminates after all input is exhausted. Normally you'd still say it's a bug if it hangs afterwards.

But you can't just say that every program has to terminate, because stuff like servers often has to run until stopped by external intervention.

So strictly speaken "no docs, no bugs" holds true. But you can still disappoint the user, and in some cases people will call that a "bug" as well.

I'll remember that for next time I need a good excuse for not having written documentation ;)

When you write software for money, you usually have some kind of requirement docs, which serve as docs as well. If not, you're lucky.

(I saw that smiley, yes, but I still wanted to express my thoughts about what a bug is and what not).