标准输入STDIN_FILENO=0 标准输出STDOUT_FILENO=1 标准错误 STDERR_FILENO=2
文件位置k=0

打开关闭

1 2	int open(char *filename, int flags, mode_t mode) int close(int fd)

读写

1 2	ssize_t read (int fd, void buf, size_t n) //从fd读取n个byte到buf里 ssize_t write(int fd, const void buf, size_t n)

ssize_t是int而size_t是unsigned int

1 2	ssize_t rio_readn (int fd, void usrbuf, size_t n) ssize_t rio_writen (int fd, void usrbuf, size_t n)

1 2	int stat(const char filename , struct stat buf) int fstat(int fd, struct stat *buf)

1	int dup2(int oldfd, int new fd)