stat

STAT(2)                       System Calls Manual                      STAT(2)

NAME
     stat, lstat, fstat, fstatat — get file status

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/stat.h>

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

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

     int
     fstat(int fd, struct stat *sb);

     int
     fstatat(int fd, const char *path, struct stat *buf, int flag);

DESCRIPTION
     The stat() system call obtains information about the file pointed to by
     path.  Read, write or execute permission of the named file is not
     required, but all directories listed in the path name leading to the file
     must be searchable.

     The lstat() system call is like stat() except when the named file is a
     symbolic link, in which case lstat() returns information about the link,
     while stat() returns information about the file the link references.

     The fstat() system call obtains the same information about an open file
     known by the file descriptor fd.

     The fstatat() system call is equivalent to stat() and lstat() except when
     the path specifies a relative path.  In this case the status is retrieved
     from a file relative to the directory associated with the file descriptor
     fd instead of the current working directory.

     The values for the flag are constructed by a bitwise-inclusive OR of
     flags from this list, defined in <fcntl.h>:

     AT_SYMLINK_NOFOLLOW
             If path names a symbolic link, the status of the symbolic link is
             returned.

     If fstatat() is passed the special value AT_FDCWD in the fd parameter,
     the current working directory is used and the behavior is identical to a
     call to stat() or lstat() respectively, depending on whether or not the
     AT_SYMLINK_NOFOLLOW bit is set in flag.

     The sb argument is a pointer to a stat structure as defined by
     <sys/stat.h> and into which information is placed concerning the file.

     The fields of struct stat related to the file system are:

     st_dev    Numeric ID of the device containing the file.

     st_ino    The file's inode number.

     st_nlink  Number of hard links to the file.

     st_flags  Flags enabled for the file.  See chflags(2) for the list of
               flags and their description.

     The st_dev and st_ino fields together identify the file uniquely within
     the system.

     The time-related fields of struct stat are:

     st_atim      Time when file data was last accessed.  Changed by the
                  mknod(2), utimes(2), read(2) and readv(2) system calls.

     st_mtim      Time when file data was last modified.  Changed by the
                  mkdir(2), mkfifo(2), mknod(2), utimes(2), write(2) and
                  writev(2) system calls.

     st_ctim      Time when file status was last changed (inode data
                  modification).  Changed by the chflags(2), chmod(2),
                  chown(2), creat(2), link(2), mkdir(2), mkfifo(2), mknod(2),
                  rename(2), rmdir(2), symlink(2), truncate(2), unlink(2),
                  utimes(2), write(2) and writev(2) system calls.

     st_birthtim  Time when the inode was created.

     These time-related macros are defined for compatibility:

     #define st_atime                st_atim.tv_sec
     #define st_mtime                st_mtim.tv_sec
     #define st_ctime                st_ctim.tv_sec
     #ifndef _POSIX_SOURCE
     #define st_birthtime            st_birthtim.tv_sec
     #endif

     #ifndef _POSIX_SOURCE
     #define st_atimespec            st_atim
     #define st_mtimespec            st_mtim
     #define st_ctimespec            st_ctim
     #define st_birthtimespec        st_birthtim
     #endif

     Size-related fields of the struct stat are:

     st_size     File size in bytes.

     st_blksize  Optimal I/O block size for the file.

     st_blocks   Actual number of blocks allocated for the file in 512-byte
                 units.  As short symbolic links are stored in the inode, this
                 number may be zero.

     The access-related fields of struct stat are:

     st_uid   User ID of the file's owner.

     st_gid   Group ID of the file.

     st_mode  Status of the file (see below).

     The status information word st_mode has these bits:

     #define S_IFMT   0170000  /* type of file mask */
     #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 */
     #define S_IRWXU  0000700  /* RWX mask for owner */
     #define S_IRUSR  0000400  /* read permission, owner */
     #define S_IWUSR  0000200  /* write permission, owner */
     #define S_IXUSR  0000100  /* execute/search permission, owner */
     #define S_IRWXG  0000070  /* RWX mask for group */
     #define S_IRGRP  0000040  /* read permission, group */
     #define S_IWGRP  0000020  /* write permission, group */
     #define S_IXGRP  0000010  /* execute/search permission, group */
     #define S_IRWXO  0000007  /* RWX mask for other */
     #define S_IROTH  0000004  /* read permission, other */
     #define S_IWOTH  0000002  /* write permission, other */
     #define S_IXOTH  0000001  /* execute/search permission, other */

     For a list of access modes, see <sys/stat.h>, access(2) and chmod(2).
     These macros are available to test whether a st_mode value passed in the
     m argument corresponds to a file of the specified type:

     S_ISBLK(m)   Test for a block special file.

     S_ISCHR(m)   Test for a character special file.

     S_ISDIR(m)   Test for a directory.

     S_ISFIFO(m)  Test for a pipe or FIFO special file.

     S_ISLNK(m)   Test for a symbolic link.

     S_ISREG(m)   Test for a regular file.

     S_ISSOCK(m)  Test for a socket.

     S_ISWHT(m)   Test for a whiteout.

     The macros evaluate to a non-zero value if the test is true or to the
     value 0 if the test is false.

RETURN VALUES
     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

COMPATIBILITY
     Previous versions of the system used different types for the st_dev,
     st_uid, st_gid, st_rdev, st_size, st_blksize and st_blocks fields.

ERRORS
     The stat() and lstat() system calls will fail if:

     [EACCES]           Search permission is denied for a component of the
                        path prefix.

     [EFAULT]           The sb or path argument points to an invalid address.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

     [ELOOP]            Too many symbolic links were encountered in
                        translating the pathname.

     [ENAMETOOLONG]     A component of a pathname exceeded 255 characters, or
                        an entire path name exceeded 1023 characters.

     [ENOENT]           The named file does not exist.

     [ENOTDIR]          A component of the path prefix is not a directory.

     [EOVERFLOW]        The file size in bytes cannot be represented correctly
                        in the structure pointed to by sb.

     The fstat() system call will fail if:

     [EBADF]            The fd argument is not a valid open file descriptor.

     [EFAULT]           The sb argument points to an invalid address.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

     [EOVERFLOW]        The file size in bytes cannot be represented correctly
                        in the structure pointed to by sb.

     In addition to the errors returned by the lstat(), the fstatat() may fail
     if:

     [EBADF]            The path argument does not specify an absolute path
                        and the fd argument is neither AT_FDCWD nor a valid
                        file descriptor open for searching.

     [EINVAL]           The value of the flag argument is not valid.

     [ENOTDIR]          The path argument is not an absolute path and fd is
                        neither AT_FDCWD nor a file descriptor associated with
                        a directory.

SEE ALSO
     access(2), chmod(2), chown(2), fhstat(2), statfs(2), utimes(2),
     sticky(7), symlink(7)

STANDARDS
     The stat() and fstat() system calls are expected to conform to ISO/IEC
     9945-1:1990 (“POSIX.1”).  The fstatat() system call follows The Open
     Group Extended API Set 2 specification.

HISTORY
     The stat() and fstat() system calls appeared in Version 1 AT&T UNIX.  The
     lstat() system call appeared in 4.2BSD.  The fstatat() system call
     appeared in FreeBSD 8.0.

BUGS
     Applying fstat() to a socket returns a zeroed buffer, except for the
     blocksize field, and a unique device and inode number.

                               December 1, 2017