Stderr

stderr is short for standard error. It is always descriptor number 2 in a unix program. In OpenBSD stderr can be represented as /dev/fd/2 or /dev/stderr. You can see more about this by typing "man 4 stderr" or "man 4 fd". Standard error is defined in /usr/include/unistd.h as a macro that is called STDERR_FILENO and its value is 2.