c常用头文件——unistd.h

#include <unistd.h>

a). 管道系统调用

int pipe(int fd[2])

b). read, write系统调用

/* Read NBYTES into BUF from FD. Return the

   number read, -1 for errors or 0 for EOF.

   This function is a cancellation point and therefore not marked with

   __THROW. */

extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur;

/* Write N bytes of BUF to FD. Return the number written, or -1.

   This function is a cancellation point and therefore not marked with

   __THROW. */

extern ssize_t write (int __fd, __const void *__buf, size_t __n) __wur;

c). 各种错误定义

EAGAIN

EWOULDBLOCK

ECHILD等