STAT(2) BSD System Calls Manual STAT(2)
fstat, fstat64, lstat, lstat64, stat, stat64 -- get file status #includeThe stat() function obtains information about the file pointed to by path. Permission toint fstat(int fildes, struct stat *buf); int lstat(const char *restrict path, struct stat *restrict buf); int stat(const char *restrict path, struct stat *restrict buf); transitiional synopsis (now deprecated) Not shown here. int fstat64(int fildes, struct stat64 *buf); int lstat64(const char *restrict path, struct stat64 *restrict buf); int stat64(const char *restrict path, struct stat64 *restrict buf);
file
is not required,
directories in the path leading to the file must be searchable (x mode).
Symbolic links do not have an owner, group, access mode, times, etc., these attributes may be taken
from the directory that contains the link. the attributes returned from an lstat() that refer to the
symbolic link itself are the file type (S_IFLNK), size, blocks, and link count (always 1).
stat() returns information about the file the link references.
lstat() returns information about the link where the named file is a symbolic link;
fstat() obtains information about an open file fields
buf is a pointer to a stat structure as defined by <sys/stat.h> where information is placed.
struct stat { dev_t st_dev; /* ID of device containing file */ mode_t st_mode; /* Mode of file */ nlink_t st_nlink; /* Number of hard links */ ino_t st_ino; /* File serial number 64 bits */ uid_t st_uid; /* User ID of the file */ gid_t st_gid; /* Group ID of the file */ dev_t st_rdev; /* Device ID */ struct timespec st_atimespec; /* time of last access */ struct timespec st_mtimespec; /* time of last data modification */ struct timespec st_ctimespec; /* time of last status change */ struct timespec st_birthtimespec; /* time of file creation(birth) added */ off_t st_size; /* file size, in bytes */ blkcnt_t st_blocks; /* blocks allocated for file */ blksize_t st_blksize; /* optimal blocksize for I/O */ uint32_t st_flags; /* user defined flags for file */ //UF_COMPRESSED uint32_t st_gen; /* file generation number */ }; The time-related fields of struct stat are as follows: st_atime data last accessed. Changed by the mknod, utimes and read (if file system has atime on) st_mtime file data last modified. Changed by the mknod, utimes and write st_ctime status was last changed (inode data modification). chmod, chown, link, mknod, rename, unlink, utimes and write st_birthtime file creation. st_blksize optimal I/O block size for the file. st_blocks number of blocks allocated for the file in 512-byte units. May be zero for symblolic links. st_mode : #define S_IFMT 0170000 /* type of file */ #define S_IFIFO 0010000 /* named pipe (fifo) */ #define S_IFCHR 0020000 /* character special */ #define S_IFDIR 0040000 /* directory */ #define S_IFBLK 0060000 /* block special */ #define S_IFREG 0100000 /* regular */ #define S_IFLNK 0120000 /* symbolic link */ #define S_IFSOCK 0140000 /* socket */ #define S_IFWHT 0160000 /* whiteout */ #define S_ISUID 0004000 /* set user id on execution */ #define S_ISGID 0002000 /* set group id on execution */ #define S_ISVTX 0001000 /* save swapped text even after use (sticky) */ #define S_IRUSR 0000400 /* read permission, user(owner) */ #define S_IWUSR 0000200 /* write permission, user(owner) */ #define S_IXUSR 0000100 /* execute/search permission, user(owner) */ For a list of access modes, see <sys/stat.h> access and chmod. For a list of the file flags in the st_flags field, see <sys/stat.h> and chflags.
fstat() system call will fail if: [EBADF] fildes is not a valid open file descriptor. [EFAULT] Sb points to an invalid address. [EIO] An I/O error occurs while reading from or writing to the file system. lstat() and stat() system calls will fail if: [EACCES] Search permission is denied for a component of the path prefix. [EFAULT] Sb or name points to an invalid address. [EIO] An I/O error occurs while reading from or writing to the file system. [ELOOP] Too many symbolic links are encountered in translating the pathname, indicative of a looping symbolic link. [ENAMETOOLONG] A component of a pathname exceeds {NAME_MAX} characters, or an entire path name exceeds {PATH_MAX} characters. [ENOENT] The named file does not exist. [ENOTDIR] A component of the path prefix is not a directory. fstat(), lstat(), and stat() system calls will fail if: [EOVERFLOW] The file size in bytes, the number of blocks allocated to the file or the file serial number cannot be represented correctly in the structure pointed to by buf.CAVEATS
Generation number, st_gen, is only available to the super-user. The stat64 structure used by these deprecated routines is the same as the stat structure when 64-bit inodes are in effect SEE ALSO chflags(2), chmod(2), chown(2), utimes(2), compat(5), statfs(2), symlink(7) BUGS Applying fstat to a socket (and thus to a pipe) returns a zero'd buffer, except for the blocksize field, and a unique device and inode number.