I noticed this when reading through Beej’s Guide to C Programming. While explaining printf, reference is made to man 3 printf - which looked different from how I usually run man. Why the 3?
So I ran man printf instead. Output:
Then man 3 printf:
And I noticed what I’d been missing. The first output has User Commands at the top, while the other one has Library Functions Manual.
As it turns out, man pages are divided into sections. I’ve never thought to check man man, but it explains this.
To check what sections are available for a command:
You may need to run sudo mandb if you get the error nothing appropriate with the above command.