#include <sys/stat.h>

int stat(const char *restrict pathname, struct stat * restrict buf);
int fstat(int fd, struct stat *buf);
int lstat(const char *restrict pathname, struct stat *restrict buf);
int fstat(int fd, const char *restrict pathname, struct stat *restrict buf, int flag);

一旦给出pathname，stat函数将返回与此命名文件有关的信息结构。

fstat函数获得已在描述符fd上打开文件的有关信息。

lstat函数类似于stat，但是当命名文件是一个符号链接时，lstat返回该符号链接的有关信息，而不是由该符号链接引用的文件的信息。

fstatat函数为一个相对于当前打开目录(由fd参数指向)的路径名返回文件统计信息。

struct stat{
        mode_t st_mode;            //file type & mode(permissions)
        ino_t st_ino;              //i-node number (serialnumber) 
        dev_t st_dev;              //device number (file system)
        dev_t st_rdev;             //device number for special files
        nlink_t st_nlink;          //numbser of links
        uid_t st_uid;              //user ID of owner
        git_t st_gid;              //group ID of owner
        off_t st_size;             //size in bytes, for regular files
        struct timespec st_atime;  //time of last access
        struct timespec st_mtime;  //time of last modification
        struct timespec st_ctime;  //time of last file status change
        blksize_t st_blksize;      //best I/O block size
        blkcnt_t st_blocks;        //number of disk blocks allocated
};