c standard library doesn't really relate directly to system calls (at least in modern os'es). In particular, the stdio.h functions are buffered by default, whil

c standard library doesn't really relate directly to system calls (at least in modern os'es). In particular, the stdio.h functions are buffered by default, while their system call analogues are not. For unixes, system call wrappers are typically found in <unistd.h>, not the "official" c standard library