I've been dealing with POSIX (or more generally "unix-y") environments for so long, when I see "No such file or directory" I automatically tend to think "ENOENT

I've been dealing with POSIX (or more generally "unix-y") environments for so long, when I see "No such file or directory" I automatically tend to think "ENOENT" and not actually "file not found", as in something did not exist. Many system calls (sysctl as just one example) happily return ENOENT when they did not find a thing no matter whether it is even remotely related to a file. I picked sysctl because it also can return ENOTDIR and EISDIR for something not related to directories at all. It's commonly not that much of an issue when you handle the error in code, but if the error gets "helpfully" bubbled up with its strerror description (instead of just a number), it can sure confuse people. Somewhat simplified: errnos were at some distant point in the past divined into existence, and system calls and system level C APIs had to make with what they got since then.