Section 2 of the unix manual is for syscalls. Section 3 is for C library functions. http://en.wikipedia.org/wiki/Man_page#Manual_sections
If libc implements it, then it is by definition in section 3.
EDIT: (signing out of this sub-thread)
If libc implements it, then it is by definition in section 3.
EDIT: (signing out of this sub-thread)
Have you ever called a system call by hand using assembly?
Have you ever looked at glibc's source?
Habe you ever looked at the kernel's close() syscall?