function stat

int  stat(const char *restrict path, struct stat *restrict buf);

get file status

struct stat {

dev_t st_dev;

ino_t st_ino;

mode_t st_mode;

nlink_t st_nlink;

uid_t st_uid;

gid_t st_gid;

dev_t st_rdev;

off_t st_size;

time_t st_atime;

time_t st_mtime;

time_t st_ctime;

blksize_t st_blksize;

blkcnt_t st_blocks;

mode_t st_attr;

}; 

struct utsname & uname

struct utsname

hold information returned by the uname function

uname(struct utsname *name)

store information identifying the current system in the structure pointed to by name.