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Unix系统API汇集

fileno: 将文件指针转换成文件描述符
int fileno(FILE *stream);
fdopen: 将文件描述符转换成文件指针
FILE *fdopen(int fd, const char *mode);

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int open(const char *pathname, int flags);
int open(const char *pathname, int flags, mode_t mode);

#include <unistd.h>
int close(int fd);

ssize_t read(int fd, void *buf, size_t count);
返回值:
错误: -1
到达文件尾: 0
成功: 返回从文件复制到规定缓冲区的字节数

ssize_t write(int fd, const void *buf, size_t count);
返回值:
错误: -1
什么都没做: 0

int fsync(int fd);

off_t lseek(int fd, off_t offset, int whence);
返回值: 新的文件偏移值;

Whence取值:
SEEK_SET
The offset is set to offset bytes.
SEEK_CUR
The offset is set to its current location plus offset bytes.
SEEK_END
The offset is set to the size of the file plus offset bytes.

#include <sys/types.h>
#include <dirent.h>
DIR *opendir(const char *name);
返回值:
成功: 返回目录指针;
失败: 返回NULL;

struct dirent *readdir(DIR *dirp);
返回值:
成功: 返回一个指向dirent结构的指针, 它包含指定目录的下一个连接的细节;
没有更多连接时, 返回0;

struct dirent
{
ino_t          d_ino;       /* inode number */
off_t          d_off;       /* not an offset; see NOTES */
unsigned short d_reclen;    /* length of this record */
unsigned char  d_type;      /* type of file; not supported
by all filesystem types */
char           d_name[256]; /* filename */
};

int closedir(DIR *dirp);

int mkdir(const char *pathname, mode_t mode);

int rmdir(const char *pathname);

Chmod, fchmod更改权限
int chmod(const char *path, mode_t mode);
int fchmod(int fd, mode_t mode);

chown,fchown更改文件所有者/所属组
int chown(const char *path, uid_t owner, gid_t group);
int fchown(int fd, uid_t owner, gid_t group);