1STAT(2)                    Linux Programmer's Manual                   STAT(2)
2
3
4

NAME

6       stat, fstat, lstat, fstatat - get file status
7

SYNOPSIS

9       #include <sys/stat.h>
10
11       int stat(const char *restrict pathname,
12                struct stat *restrict statbuf);
13       int fstat(int fd, struct stat *statbuf);
14       int lstat(const char *restrict pathname,
15                struct stat *restrict statbuf);
16
17       #include <fcntl.h>           /* Definition of AT_* constants */
18       #include <sys/stat.h>
19
20       int fstatat(int dirfd, const char *restrict pathname,
21                struct stat *restrict statbuf, int flags);
22
23   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
24
25       lstat():
26           /* Since glibc 2.20 */ _DEFAULT_SOURCE
27               || _XOPEN_SOURCE >= 500
28               || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L
29               || /* Glibc 2.19 and earlier */ _BSD_SOURCE
30
31       fstatat():
32           Since glibc 2.10:
33               _POSIX_C_SOURCE >= 200809L
34           Before glibc 2.10:
35               _ATFILE_SOURCE
36

DESCRIPTION

38       These  functions return information about a file, in the buffer pointed
39       to by statbuf.  No permissions are required on the file itself,  but—in
40       the  case of stat(), fstatat(), and lstat()—execute (search) permission
41       is required on all of the directories in  pathname  that  lead  to  the
42       file.
43
44       stat()  and fstatat() retrieve information about the file pointed to by
45       pathname; the differences for fstatat() are described below.
46
47       lstat() is identical to stat(), except that if pathname is  a  symbolic
48       link,  then  it returns information about the link itself, not the file
49       that the link refers to.
50
51       fstat() is identical to stat(), except that the file about which infor‐
52       mation is to be retrieved is specified by the file descriptor fd.
53
54   The stat structure
55       All  of  these system calls return a stat structure, which contains the
56       following fields:
57
58           struct stat {
59               dev_t     st_dev;         /* ID of device containing file */
60               ino_t     st_ino;         /* Inode number */
61               mode_t    st_mode;        /* File type and mode */
62               nlink_t   st_nlink;       /* Number of hard links */
63               uid_t     st_uid;         /* User ID of owner */
64               gid_t     st_gid;         /* Group ID of owner */
65               dev_t     st_rdev;        /* Device ID (if special file) */
66               off_t     st_size;        /* Total size, in bytes */
67               blksize_t st_blksize;     /* Block size for filesystem I/O */
68               blkcnt_t  st_blocks;      /* Number of 512B blocks allocated */
69
70               /* Since Linux 2.6, the kernel supports nanosecond
71                  precision for the following timestamp fields.
72                  For the details before Linux 2.6, see NOTES. */
73
74               struct timespec st_atim;  /* Time of last access */
75               struct timespec st_mtim;  /* Time of last modification */
76               struct timespec st_ctim;  /* Time of last status change */
77
78           #define st_atime st_atim.tv_sec      /* Backward compatibility */
79           #define st_mtime st_mtim.tv_sec
80           #define st_ctime st_ctim.tv_sec
81           };
82
83       Note: the order of fields in the stat structure varies somewhat  across
84       architectures.   In  addition,  the  definition above does not show the
85       padding bytes that may be present between some fields on various archi‐
86       tectures.  Consult the glibc and kernel source code if you need to know
87       the details.
88
89       Note: for performance and simplicity reasons, different fields  in  the
90       stat  structure  may  contain  state information from different moments
91       during the execution of the system call.  For example,  if  st_mode  or
92       st_uid  is  changed by another process by calling chmod(2) or chown(2),
93       stat() might return the old st_mode together with the  new  st_uid,  or
94       the old st_uid together with the new st_mode.
95
96       The fields in the stat structure are as follows:
97
98       st_dev This  field  describes  the  device  on which this file resides.
99              (The major(3) and minor(3) macros may be useful to decompose the
100              device ID in this field.)
101
102       st_ino This field contains the file's inode number.
103
104       st_mode
105              This  field  contains  the file type and mode.  See inode(7) for
106              further information.
107
108       st_nlink
109              This field contains the number of hard links to the file.
110
111       st_uid This field contains the user ID of the owner of the file.
112
113       st_gid This field contains the ID of the group owner of the file.
114
115       st_rdev
116              This field describes the device that this  file  (inode)  repre‐
117              sents.
118
119       st_size
120              This  field  gives the size of the file (if it is a regular file
121              or a symbolic link) in bytes.  The size of a  symbolic  link  is
122              the  length  of  the pathname it contains, without a terminating
123              null byte.
124
125       st_blksize
126              This field  gives  the  "preferred"  block  size  for  efficient
127              filesystem I/O.
128
129       st_blocks
130              This field indicates the number of blocks allocated to the file,
131              in 512-byte units.  (This may be smaller than  st_size/512  when
132              the file has holes.)
133
134       st_atime
135              This is the time of the last access of file data.
136
137       st_mtime
138              This is the time of last modification of file data.
139
140       st_ctime
141              This  is  the  file's last status change timestamp (time of last
142              change to the inode).
143
144       For further information on the above fields, see inode(7).
145
146   fstatat()
147       The fstatat() system call is a more  general  interface  for  accessing
148       file  information  which can still provide exactly the behavior of each
149       of stat(), lstat(), and fstat().
150
151       If the pathname given in pathname is relative, then it  is  interpreted
152       relative  to  the  directory  referred  to by the file descriptor dirfd
153       (rather than relative to the current working directory of  the  calling
154       process, as is done by stat() and lstat() for a relative pathname).
155
156       If  pathname  is relative and dirfd is the special value AT_FDCWD, then
157       pathname is interpreted relative to the current  working  directory  of
158       the calling process (like stat() and lstat()).
159
160       If pathname is absolute, then dirfd is ignored.
161
162       flags  can  either  be 0, or include one or more of the following flags
163       ORed:
164
165       AT_EMPTY_PATH (since Linux 2.6.39)
166              If pathname is an empty string, operate on the file referred  to
167              by  dirfd (which may have been obtained using the open(2) O_PATH
168              flag).  In this case, dirfd can refer to any type of  file,  not
169              just  a  directory,  and the behavior of fstatat() is similar to
170              that of fstat().  If dirfd is AT_FDCWD, the call operates on the
171              current  working directory.  This flag is Linux-specific; define
172              _GNU_SOURCE to obtain its definition.
173
174       AT_NO_AUTOMOUNT (since Linux 2.6.38)
175              Don't automount the terminal ("basename") component of  pathname
176              if  it  is  a directory that is an automount point.  This allows
177              the caller to gather attributes of an  automount  point  (rather
178              than the location it would mount).  Since Linux 4.14, also don't
179              instantiate a nonexistent name in an on-demand directory such as
180              used  for automounter indirect maps.  This flag has no effect if
181              the mount point has already been mounted over.
182
183              Both stat() and lstat() act as though AT_NO_AUTOMOUNT was set.
184
185              The AT_NO_AUTOMOUNT can be used in tools that  scan  directories
186              to prevent mass-automounting of a directory of automount points.
187
188              This  flag  is  Linux-specific; define _GNU_SOURCE to obtain its
189              definition.
190
191       AT_SYMLINK_NOFOLLOW
192              If pathname is a symbolic link, do not dereference  it:  instead
193              return information about the link itself, like lstat().  (By de‐
194              fault, fstatat() dereferences symbolic links, like stat().)
195
196       See openat(2) for an explanation of the need for fstatat().
197

RETURN VALUE

199       On success, zero is returned.  On error, -1 is returned, and  errno  is
200       set to indicate the error.
201

ERRORS

203       EACCES Search  permission  is  denied for one of the directories in the
204              path prefix of pathname.  (See also path_resolution(7).)
205
206       EBADF  fd is not a valid open file descriptor.
207
208       EBADF  (fstatat()) pathname is relative but dirfd is  neither  AT_FDCWD
209              nor a valid file descriptor.
210
211       EFAULT Bad address.
212
213       EINVAL (fstatat()) Invalid flag specified in flags.
214
215       ELOOP  Too many symbolic links encountered while traversing the path.
216
217       ENAMETOOLONG
218              pathname is too long.
219
220       ENOENT A component of pathname does not exist or is a dangling symbolic
221              link.
222
223       ENOENT pathname is an empty string and AT_EMPTY_PATH was not  specified
224              in flags.
225
226       ENOMEM Out of memory (i.e., kernel memory).
227
228       ENOTDIR
229              A component of the path prefix of pathname is not a directory.
230
231       ENOTDIR
232              (fstatat())  pathname is relative and dirfd is a file descriptor
233              referring to a file other than a directory.
234
235       EOVERFLOW
236              pathname or fd refers to a file whose  size,  inode  number,  or
237              number  of  blocks  cannot  be represented in, respectively, the
238              types off_t, ino_t, or blkcnt_t.  This error can occur when, for
239              example,  an  application  compiled on a 32-bit platform without
240              -D_FILE_OFFSET_BITS=64 calls stat() on a file whose size exceeds
241              (1<<31)-1 bytes.
242

VERSIONS

244       fstatat()  was  added  to  Linux  in kernel 2.6.16; library support was
245       added to glibc in version 2.4.
246

CONFORMING TO

248       stat(), fstat(), lstat(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1.2008.
249
250       fstatat(): POSIX.1-2008.
251
252       According to POSIX.1-2001, lstat() on a symbolic link need return valid
253       information  only in the st_size field and the file type of the st_mode
254       field of the stat structure.  POSIX.1-2008 tightens the  specification,
255       requiring  lstat() to return valid information in all fields except the
256       mode bits in st_mode.
257
258       Use of the st_blocks and st_blksize fields may be less portable.  (They
259       were  introduced  in  BSD.  The interpretation differs between systems,
260       and possibly on a single system when NFS mounts are involved.)
261

NOTES

263   Timestamp fields
264       Older kernels and older standards did not support nanosecond  timestamp
265       fields.  Instead, there were three timestamp fields—st_atime, st_mtime,
266       and st_ctime—typed as time_t that recorded timestamps  with  one-second
267       precision.
268
269       Since  kernel 2.5.48, the stat structure supports nanosecond resolution
270       for the three file timestamp fields.  The nanosecond components of each
271       timestamp are available via names of the form st_atim.tv_nsec, if suit‐
272       able feature test macros are defined.  Nanosecond timestamps were stan‐
273       dardized  in  POSIX.1-2008,  and, starting with version 2.12, glibc ex‐
274       poses the nanosecond component names if _POSIX_C_SOURCE is defined with
275       the  value  200809L  or  greater,  or _XOPEN_SOURCE is defined with the
276       value 700 or greater.  Up to and including glibc 2.19, the  definitions
277       of  the  nanoseconds  components  are  also  defined  if _BSD_SOURCE or
278       _SVID_SOURCE is defined.  If none of the aforementioned macros are  de‐
279       fined,  then  the  nanosecond values are exposed with names of the form
280       st_atimensec.
281
282   C library/kernel differences
283       Over time, increases in the size of the  stat  structure  have  led  to
284       three  successive  versions  of stat(): sys_stat() (slot __NR_oldstat),
285       sys_newstat() (slot __NR_stat), and sys_stat64() (slot __NR_stat64)  on
286       32-bit  platforms  such  as  i386.  The first two versions were already
287       present in Linux 1.0 (albeit with different names); the last was  added
288       in Linux 2.4.  Similar remarks apply for fstat() and lstat().
289
290       The  kernel-internal  versions  of the stat structure dealt with by the
291       different versions are, respectively:
292
293       __old_kernel_stat
294              The original structure, with rather narrow fields, and  no  pad‐
295              ding.
296
297       stat   Larger  st_ino  field  and padding added to various parts of the
298              structure to allow for future expansion.
299
300       stat64 Even larger st_ino field, larger st_uid and st_gid fields to ac‐
301              commodate  the  Linux-2.4 expansion of UIDs and GIDs to 32 bits,
302              and various other enlarged fields and  further  padding  in  the
303              structure.   (Various  padding bytes were eventually consumed in
304              Linux 2.6, with the advent of 32-bit device IDs  and  nanosecond
305              components for the timestamp fields.)
306
307       The  glibc  stat()  wrapper  function hides these details from applica‐
308       tions, invoking the most recent version of the system call provided  by
309       the  kernel, and repacking the returned information if required for old
310       binaries.
311
312       On modern 64-bit systems, life is simpler: there  is  a  single  stat()
313       system  call  and  the kernel deals with a stat structure that contains
314       fields of a sufficient size.
315
316       The underlying system call employed  by  the  glibc  fstatat()  wrapper
317       function  is  actually  called  fstatat64()  or, on some architectures,
318       newfstatat().
319

EXAMPLES

321       The following program calls lstat() and displays selected fields in the
322       returned stat structure.
323
324       #include <sys/types.h>
325       #include <sys/stat.h>
326       #include <stdint.h>
327       #include <time.h>
328       #include <stdio.h>
329       #include <stdlib.h>
330       #include <sys/sysmacros.h>
331
332       int
333       main(int argc, char *argv[])
334       {
335           struct stat sb;
336
337           if (argc != 2) {
338               fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);
339               exit(EXIT_FAILURE);
340           }
341
342           if (lstat(argv[1], &sb) == -1) {
343               perror("lstat");
344               exit(EXIT_FAILURE);
345           }
346
347           printf("ID of containing device:  [%jx,%jx]\n",
348                   (uintmax_t) major(sb.st_dev),
349                   (uintmax_t) minor(sb.st_dev));
350
351           printf("File type:                ");
352
353           switch (sb.st_mode & S_IFMT) {
354           case S_IFBLK:  printf("block device\n");            break;
355           case S_IFCHR:  printf("character device\n");        break;
356           case S_IFDIR:  printf("directory\n");               break;
357           case S_IFIFO:  printf("FIFO/pipe\n");               break;
358           case S_IFLNK:  printf("symlink\n");                 break;
359           case S_IFREG:  printf("regular file\n");            break;
360           case S_IFSOCK: printf("socket\n");                  break;
361           default:       printf("unknown?\n");                break;
362           }
363
364           printf("I-node number:            %ju\n", (uintmax_t) sb.st_ino);
365
366           printf("Mode:                     %jo (octal)\n",
367                   (uintmax_t) sb.st_mode);
368
369           printf("Link count:               %ju\n", (uintmax_t) sb.st_nlink);
370           printf("Ownership:                UID=%ju   GID=%ju\n",
371                   (uintmax_t) sb.st_uid, (uintmax_t) sb.st_gid);
372
373           printf("Preferred I/O block size: %jd bytes\n",
374                   (intmax_t) sb.st_blksize);
375           printf("File size:                %jd bytes\n",
376                   (intmax_t) sb.st_size);
377           printf("Blocks allocated:         %jd\n",
378                   (intmax_t) sb.st_blocks);
379
380           printf("Last status change:       %s", ctime(&sb.st_ctime));
381           printf("Last file access:         %s", ctime(&sb.st_atime));
382           printf("Last file modification:   %s", ctime(&sb.st_mtime));
383
384           exit(EXIT_SUCCESS);
385       }
386

SEE ALSO

388       ls(1),  stat(1),  access(2), chmod(2), chown(2), readlink(2), statx(2),
389       utime(2), capabilities(7), inode(7), symlink(7)
390

COLOPHON

392       This page is part of release 5.13 of the Linux  man-pages  project.   A
393       description  of  the project, information about reporting bugs, and the
394       latest    version    of    this    page,    can     be     found     at
395       https://www.kernel.org/doc/man-pages/.
396
397
398
399Linux                             2021-08-27                           STAT(2)
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