STAT(2)                    Linux Programmer's Manual                   STAT(2)

       stat, fstat, lstat, fstatat - get file status

       #include <sys/types.h>
       #include <sys/stat.h>
       #include <unistd.h>

       int stat(const char *pathname, struct stat *statbuf);
       int fstat(int fd, struct stat *statbuf);
       int lstat(const char *pathname, struct stat *statbuf);

       #include <fcntl.h>           /* Definition of AT_* constants */
       #include <sys/stat.h>

       int fstatat(int dirfd, const char *pathname, struct stat *statbuf,
                   int flags);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

           /* glibc 2.19 and earlier */ _BSD_SOURCE
               || /* Since glibc 2.20 */ _DEFAULT_SOURCE
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L

           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:

       These  functions return information about a file, in the buffer pointed
       to by statbuf.  No permissions are required on the file itself, but--in
       the case of stat(), fstatat(), and lstat()--execute (search) permission
       is required on all of the directories in  pathname  that  lead  to  the

       stat()  and fstatat() retrieve information about the file pointed to by
       pathname; the differences for fstatat() are described below.

       lstat() is identical to stat(), except that if pathname is  a  symbolic
       link,  then  it returns information about the link itself, not the file
       that it refers to.

       fstat() is identical to stat(), except that the file about which infor-
       mation is to be retrieved is specified by the file descriptor fd.

   The stat structure
       All  of  these system calls return a stat structure, which contains the
       following fields:

           struct stat {
               dev_t     st_dev;         /* ID of device containing file */
               ino_t     st_ino;         /* Inode number */
               mode_t    st_mode;        /* File type and mode */
               nlink_t   st_nlink;       /* Number of hard links */
               uid_t     st_uid;         /* User ID of owner */
               gid_t     st_gid;         /* Group ID of owner */
               dev_t     st_rdev;        /* Device ID (if special file) */
               off_t     st_size;        /* Total size, in bytes */
               blksize_t st_blksize;     /* Block size for filesystem I/O */
               blkcnt_t  st_blocks;      /* Number of 512B blocks allocated */

               /* Since Linux 2.6, the kernel supports nanosecond
                  precision for the following timestamp fields.
                  For the details before Linux 2.6, see NOTES. */

               struct timespec st_atim;  /* Time of last access */
               struct timespec st_mtim;  /* Time of last modification */
               struct timespec st_ctim;  /* Time of last status change */

           #define st_atime st_atim.tv_sec      /* Backward compatibility */
           #define st_mtime st_mtim.tv_sec
           #define st_ctime st_ctim.tv_sec

       Note: the order of fields in the stat structure varies somewhat  across
       architectures.   In  addition,  the  definition above does not show the
       padding bytes that may be present between some fields on various archi-
       tectures.  Consult the glibc and kernel source code if you need to know
       the details.

       Note: for performance and simplicity reasons, different fields  in  the
       stat  structure  may  contain  state information from different moments
       during the execution of the system call.  For example,  if  st_mode  or
       st_uid  is  changed by another process by calling chmod(2) or chown(2),
       stat() might return the old st_mode together with the  new  st_uid,  or
       the old st_uid together with the new st_mode.

       The fields in the stat structure are as follows:

       st_dev This  field  describes  the  device  on which this file resides.
              (The major(3) and minor(3) macros may be useful to decompose the
              device ID in this field.)

       st_ino This field contains the file's inode number.

              This  field  contains  the file type and mode.  See inode(7) for
              further information.

              This field contains the number of hard links to the file.

       st_uid This field contains the user ID of the owner of the file.

       st_gid This field contains the ID of the group owner of the file.

              This field describes the device that this  file  (inode)  repre-

              This  field  gives the size of the file (if it is a regular file
              or a symbolic link) in bytes.  The size of a  symbolic  link  is
              the  length  of  the pathname it contains, without a terminating
              null byte.

              This field  gives  the  "preferred"  block  size  for  efficient
              filesystem I/O.

              This field indicates the number of blocks allocated to the file,
              in 512-byte units.  (This may be smaller than  st_size/512  when
              the file has holes.)

              This is the file's last access timestamp.

              This is the file's last modification timestamp.

              This is the file's last status change timestamp.

       For further information on the above fields, see inode(7).

       The  fstatat()  system  call  is a more general interface for accessing
       file information which can still provide exactly the behavior  of  each
       of stat(), lstat(), and fstat().

       If  the  pathname given in pathname is relative, then it is interpreted
       relative to the directory referred to  by  the  file  descriptor  dirfd
       (rather  than  relative to the current working directory of the calling
       process, as is done by stat() and lstat() for a relative pathname).

       If pathname is relative and dirfd is the special value  AT_FDCWD,  then
       pathname  is  interpreted  relative to the current working directory of
       the calling process (like stat() and lstat()).

       If pathname is absolute, then dirfd is ignored.

       flags can either be 0, or include one or more of  the  following  flags

       AT_EMPTY_PATH (since Linux 2.6.39)
              If  pathname is an empty string, operate on the file referred to
              by dirfd (which may have been obtained using the open(2)  O_PATH
              flag).   In  this case, dirfd can refer to any type of file, not
              just a directory, and the behavior of fstatat()  is  similar  to
              that of fstat().  If dirfd is AT_FDCWD, the call operates on the
              current working directory.  This flag is Linux-specific;  define
              _GNU_SOURCE to obtain its definition.

       AT_NO_AUTOMOUNT (since Linux 2.6.38)
              Don't  automount the terminal ("basename") component of pathname
              if it is a directory that is an automount  point.   This  allows
              the  caller  to  gather attributes of an automount point (rather
              than the location it would mount).  Since Linux 4.14, also don't
              instantiate a nonexistent name in an on-demand directory such as
              used for automounter indirect maps.  This flag can  be  used  in
              tools  that  scan  directories to prevent mass-automounting of a
              directory of automount points.  The AT_NO_AUTOMOUNT flag has  no
              effect  if  the mount point has already been mounted over.  This
              flag is Linux-specific; define _GNU_SOURCE to obtain its defini-
              tion.  Both stat() and lstat() act as though AT_NO_AUTOMOUNT was

              If pathname is a symbolic link, do not dereference  it:  instead
              return  information  about  the  link itself, like lstat().  (By
              default, fstatat() dereferences symbolic links, like stat().)

       See openat(2) for an explanation of the need for fstatat().

       On success, zero is returned.  On error, -1 is returned, and  errno  is
       set appropriately.

       EACCES Search  permission  is  denied for one of the directories in the
              path prefix of pathname.  (See also path_resolution(7).)

       EBADF  fd is not a valid open file descriptor.

       EFAULT Bad address.

       ELOOP  Too many symbolic links encountered while traversing the path.

              pathname is too long.

       ENOENT A component of pathname does not exist, or pathname is an  empty
              string and AT_EMPTY_PATH was not specified in flags.

       ENOMEM Out of memory (i.e., kernel memory).

              A component of the path prefix of pathname is not a directory.

              pathname  or  fd  refers  to a file whose size, inode number, or
              number of blocks cannot be  represented  in,  respectively,  the
              types off_t, ino_t, or blkcnt_t.  This error can occur when, for
              example, an application compiled on a  32-bit  platform  without
              -D_FILE_OFFSET_BITS=64 calls stat() on a file whose size exceeds
              (1<<31)-1 bytes.

       The following additional errors can occur for fstatat():

       EBADF  dirfd is not a valid file descriptor.

       EINVAL Invalid flag specified in flags.

              pathname is relative and dirfd is a file descriptor referring to
              a file other than a directory.

       fstatat()  was  added  to  Linux  in kernel 2.6.16; library support was
       added to glibc in version 2.4.

       stat(), fstat(), lstat(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1.2008.

       fstatat(): POSIX.1-2008.

       According to POSIX.1-2001, lstat() on a symbolic link need return valid
       information  only in the st_size field and the file type of the st_mode
       field of the stat structure.  POSIX.1-2008 tightens the  specification,
       requiring  lstat() to return valid information in all fields except the
       mode bits in st_mode.

       Use of the st_blocks and st_blksize fields may be less portable.  (They
       were  introduced  in  BSD.  The interpretation differs between systems,
       and possibly on a single system when NFS mounts are involved.)

   Timestamp fields
       Older kernels and older standards did not support nanosecond  timestamp
       fields.    Instead,   there   were  three  timestamp  fields--st_atime,
       st_mtime, and st_ctime--typed as time_t that recorded  timestamps  with
       one-second precision.

       Since  kernel 2.5.48, the stat structure supports nanosecond resolution
       for the three file timestamp fields.  The nanosecond components of each
       timestamp are available via names of the form st_atim.tv_nsec, if suit-
       able feature test macros are defined.  Nanosecond timestamps were stan-
       dardized  in  POSIX.1-2008,  and,  starting  with  version  2.12, glibc
       exposes the nanosecond component names if  _POSIX_C_SOURCE  is  defined
       with the value 200809L or greater, or _XOPEN_SOURCE is defined with the
       value 700 or greater.  Up to and including glibc 2.19, the  definitions
       of  the  nanoseconds  components  are  also  defined  if _BSD_SOURCE or
       _SVID_SOURCE is defined.  If none  of  the  aforementioned  macros  are
       defined,  then the nanosecond values are exposed with names of the form

   C library/kernel differences
       Over time, increases in the size of the  stat  structure  have  led  to
       three  successive  versions  of stat(): sys_stat() (slot __NR_oldstat),
       sys_newstat() (slot __NR_stat), and sys_stat64() (slot __NR_stat64)  on
       32-bit  platforms  such  as  i386.  The first two versions were already
       present in Linux 1.0 (albeit with different names); the last was  added
       in Linux 2.4.  Similar remarks apply for fstat() and lstat().

       The  kernel-internal  versions  of the stat structure dealt with by the
       different versions are, respectively:

              The original structure, with rather narrow fields, and  no  pad-

       stat   Larger  st_ino  field  and padding added to various parts of the
              structure to allow for future expansion.

       stat64 Even larger st_ino field, larger st_uid  and  st_gid  fields  to
              accommodate the Linux-2.4 expansion of UIDs and GIDs to 32 bits,
              and various other enlarged fields and  further  padding  in  the
              structure.   (Various  padding bytes were eventually consumed in
              Linux 2.6, with the advent of 32-bit device IDs  and  nanosecond
              components for the timestamp fields.)

       The  glibc  stat()  wrapper  function hides these details from applica-
       tions, invoking the most recent version of the system call provided  by
       the  kernel, and repacking the returned information if required for old

       On modern 64-bit systems, life is simpler: there  is  a  single  stat()
       system  call  and  the kernel deals with a stat structure that contains
       fields of a sufficient size.

       The underlying system call employed  by  the  glibc  fstatat()  wrapper
       function  is  actually  called  fstatat64()  or, on some architectures,

       The following program calls lstat() and displays selected fields in the
       returned stat structure.

       #include <sys/types.h>
       #include <sys/stat.h>
       #include <time.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <sys/sysmacros.h>

       main(int argc, char *argv[])
           struct stat sb;

           if (argc != 2) {
               fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);


           if (lstat(argv[1], &sb) == -1) {

           printf("ID of containing device:  [%lx,%lx]\n",
                (long) major(sb.st_dev), (long) minor(sb.st_dev));

           printf("File type:                ");

           switch (sb.st_mode & S_IFMT) {
           case S_IFBLK:  printf("block device\n");            break;
           case S_IFCHR:  printf("character device\n");        break;
           case S_IFDIR:  printf("directory\n");               break;
           case S_IFIFO:  printf("FIFO/pipe\n");               break;
           case S_IFLNK:  printf("symlink\n");                 break;
           case S_IFREG:  printf("regular file\n");            break;
           case S_IFSOCK: printf("socket\n");                  break;
           default:       printf("unknown?\n");                break;

           printf("I-node number:            %ld\n", (long) sb.st_ino);

           printf("Mode:                     %lo (octal)\n",
                   (unsigned long) sb.st_mode);

           printf("Link count:               %ld\n", (long) sb.st_nlink);
           printf("Ownership:                UID=%ld   GID=%ld\n",
                   (long) sb.st_uid, (long) sb.st_gid);

           printf("Preferred I/O block size: %ld bytes\n",
                   (long) sb.st_blksize);
           printf("File size:                %lld bytes\n",
                   (long long) sb.st_size);
           printf("Blocks allocated:         %lld\n",
                   (long long) sb.st_blocks);

           printf("Last status change:       %s", ctime(&sb.st_ctime));
           printf("Last file access:         %s", ctime(&sb.st_atime));
           printf("Last file modification:   %s", ctime(&sb.st_mtime));


       ls(1),  stat(1),  access(2), chmod(2), chown(2), readlink(2), utime(2),
       capabilities(7), inode(7), symlink(7)

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Linux                             2017-09-15                           STAT(2)
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