]>
Commit | Line | Data |
---|---|---|
fea681da | 1 | '\" t |
fea681da MK |
2 | .\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992 |
3 | .\" Parts Copyright (c) 1995 Nicolai Langfeldt (janl@ifi.uio.no), 1/1/95 | |
40084043 | 4 | .\" and Copyright (c) 2006, 2007, 2014 Michael Kerrisk <mtk.manpages@gmail.com> |
fea681da | 5 | .\" |
93015253 | 6 | .\" %%%LICENSE_START(VERBATIM) |
fea681da MK |
7 | .\" Permission is granted to make and distribute verbatim copies of this |
8 | .\" manual provided the copyright notice and this permission notice are | |
9 | .\" preserved on all copies. | |
10 | .\" | |
11 | .\" Permission is granted to copy and distribute modified versions of this | |
12 | .\" manual under the conditions for verbatim copying, provided that the | |
13 | .\" entire resulting derived work is distributed under the terms of a | |
14 | .\" permission notice identical to this one. | |
c13182ef | 15 | .\" |
fea681da MK |
16 | .\" Since the Linux kernel and libraries are constantly changing, this |
17 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
18 | .\" responsibility for errors or omissions, or for damages resulting from | |
19 | .\" the use of the information contained herein. The author(s) may not | |
20 | .\" have taken the same level of care in the production of this manual, | |
21 | .\" which is licensed free of charge, as they might when working | |
22 | .\" professionally. | |
c13182ef | 23 | .\" |
fea681da MK |
24 | .\" Formatted or processed versions of this manual, if unaccompanied by |
25 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 26 | .\" %%%LICENSE_END |
fea681da MK |
27 | .\" |
28 | .\" Modified by Michael Haardt <michael@moria.de> | |
29 | .\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu> | |
30 | .\" Modified 1995-05-18 by Todd Larason <jtl@molehill.org> | |
31 | .\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com> | |
32 | .\" Modified 1995-01-09 by Richard Kettlewell <richard@greenend.org.uk> | |
33 | .\" Modified 1998-05-13 by Michael Haardt <michael@cantor.informatik.rwth-aachen.de> | |
34 | .\" Modified 1999-07-06 by aeb & Albert Cahalan | |
35 | .\" Modified 2000-01-07 by aeb | |
c11b1abf | 36 | .\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com> |
bc7ff20e | 37 | .\" 2007-06-08 mtk: Added example program |
cd667553 | 38 | .\" 2007-07-05 mtk: Added details on underlying system call interfaces |
c13182ef | 39 | .\" |
c73595c2 | 40 | .TH STAT 2 2015-04-19 "Linux" "Linux Programmer's Manual" |
fea681da | 41 | .SH NAME |
40084043 | 42 | stat, fstat, lstat, fstatat \- get file status |
fea681da | 43 | .SH SYNOPSIS |
40084043 | 44 | .nf |
fea681da MK |
45 | .B #include <sys/types.h> |
46 | .br | |
47 | .B #include <sys/stat.h> | |
48 | .br | |
49 | .B #include <unistd.h> | |
50 | .sp | |
66cbeaf4 | 51 | .BI "int stat(const char *" pathname ", struct stat *" buf ); |
fea681da | 52 | .br |
d3b03141 | 53 | .BI "int fstat(int " fd ", struct stat *" buf ); |
fea681da | 54 | .br |
66cbeaf4 | 55 | .BI "int lstat(const char *" pathname ", struct stat *" buf ); |
8179def1 | 56 | .sp |
40084043 MK |
57 | .BR "#include <fcntl.h> " "/* Definition of AT_* constants */" |
58 | .B #include <sys/stat.h> | |
59 | .sp | |
60 | .BI "int fstatat(int " dirfd ", const char *" pathname ", struct stat *" \ | |
61 | buf , | |
62 | .BI " int " flags ); | |
63 | .fi | |
64 | .sp | |
8179def1 MK |
65 | .in -4n |
66 | Feature Test Macro Requirements for glibc (see | |
67 | .BR feature_test_macros (7)): | |
68 | .in | |
43e0fe7d MK |
69 | .ad l |
70 | .PD 0 | |
8179def1 MK |
71 | .sp |
72 | .BR lstat (): | |
43e0fe7d | 73 | .RS 4 |
afb9bd5d MK |
74 | /* glibc 2.19 and earlier */ _BSD_SOURCE || |
75 | .br | |
76 | /* Since glibc 2.20 */_DEFAULT_SOURCE || | |
77 | .br | |
78 | _XOPEN_SOURCE\ >=\ 500 || | |
43e0fe7d | 79 | _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED |
3ba63d80 MK |
80 | .br |
81 | || /* Since glibc 2.10: */ _POSIX_C_SOURCE\ >=\ 200112L | |
43e0fe7d | 82 | .RE |
40084043 MK |
83 | .sp |
84 | .BR fstatat (): | |
85 | .PD 0 | |
86 | .ad l | |
87 | .RS 4 | |
88 | .TP 4 | |
89 | Since glibc 2.10: | |
90 | _XOPEN_SOURCE\ >=\ 700 || _POSIX_C_SOURCE\ >=\ 200809L | |
91 | .TP | |
92 | Before glibc 2.10: | |
93 | _ATFILE_SOURCE | |
94 | .RE | |
43e0fe7d MK |
95 | .PD |
96 | .ad | |
fea681da MK |
97 | .SH DESCRIPTION |
98 | .PP | |
e096bd70 MK |
99 | These functions return information about a file, in the buffer pointed to by |
100 | .IR stat . | |
5503c85e | 101 | No permissions are required on the file itself, but\(emin the case of |
071d1c4f MK |
102 | .BR stat (), |
103 | .BR fstatat (), | |
c13182ef | 104 | and |
827edbd2 MK |
105 | .BR lstat ()\(emexecute |
106 | (search) permission is required on all of the directories in | |
66cbeaf4 | 107 | .I pathname |
da2d9dad | 108 | that lead to the file. |
fea681da | 109 | .PP |
da2d9dad | 110 | .BR stat () |
071d1c4f MK |
111 | and |
112 | .BR fstatat () | |
e096bd70 MK |
113 | retrieve information about the file pointed to by |
114 | .IR pathname ; | |
071d1c4f MK |
115 | the differences for |
116 | .BR fstatat () | |
117 | are described below. | |
fea681da | 118 | |
da2d9dad | 119 | .BR lstat () |
fea681da | 120 | is identical to |
da2d9dad MK |
121 | .BR stat (), |
122 | except that if | |
66cbeaf4 | 123 | .I pathname |
e096bd70 | 124 | is a symbolic link, then it returns information about the link itself, |
fea681da MK |
125 | not the file that it refers to. |
126 | ||
da2d9dad | 127 | .BR fstat () |
fea681da | 128 | is identical to |
da2d9dad | 129 | .BR stat (), |
5201bb40 | 130 | except that the file about which information is to be retrieved |
e096bd70 | 131 | is specified by the file descriptor |
d3b03141 | 132 | .IR fd . |
fea681da | 133 | .PP |
da2d9dad | 134 | All of these system calls return a |
fea681da MK |
135 | .I stat |
136 | structure, which contains the following fields: | |
137 | .PP | |
bd191423 | 138 | .in +4n |
fea681da MK |
139 | .nf |
140 | struct stat { | |
e9e9e87e MK |
141 | dev_t st_dev; /* ID of device containing file */ |
142 | ino_t st_ino; /* inode number */ | |
143 | mode_t st_mode; /* protection */ | |
144 | nlink_t st_nlink; /* number of hard links */ | |
145 | uid_t st_uid; /* user ID of owner */ | |
146 | gid_t st_gid; /* group ID of owner */ | |
147 | dev_t st_rdev; /* device ID (if special file) */ | |
148 | off_t st_size; /* total size, in bytes */ | |
149 | blksize_t st_blksize; /* blocksize for filesystem I/O */ | |
150 | blkcnt_t st_blocks; /* number of 512B blocks allocated */ | |
151 | ||
152 | /* Since Linux 2.6, the kernel supports nanosecond | |
153 | precision for the following timestamp fields. | |
154 | For the details before Linux 2.6, see NOTES. */ | |
155 | ||
156 | struct timespec st_atim; /* time of last access */ | |
157 | struct timespec st_mtim; /* time of last modification */ | |
158 | struct timespec st_ctim; /* time of last status change */ | |
159 | ||
160 | #define st_atime st_atim.tv_sec /* Backward compatibility */ | |
161 | #define st_mtime st_mtim.tv_sec | |
162 | #define st_ctime st_ctim.tv_sec | |
fea681da MK |
163 | }; |
164 | .fi | |
bd191423 | 165 | .in |
496bdb56 MK |
166 | |
167 | .I Note: | |
168 | the order of fields in the | |
169 | .I stat | |
170 | structure varies somewhat | |
171 | across architectures. | |
172 | In addition, | |
173 | the definition above does not show the padding bytes | |
174 | that may be present between some fields on various architectures. | |
409b0278 | 175 | Consult the glibc and kernel source code |
496bdb56 MK |
176 | if you need to know the details. |
177 | ||
f240296d JH |
178 | \# Background: inode attributes are modified with i_mutex held, but |
179 | \# read by stat() without taking the mutex. | |
180 | .I Note: | |
181 | For performance and simplicity reasons, different fields in the | |
182 | .I stat | |
183 | structure may contain state information from different moments | |
184 | during the execution of the syscall. For example, if | |
185 | .IR st_mode , | |
186 | .IR st_uid | |
187 | and | |
188 | .IR st_gid | |
189 | are changed by another process by calling | |
190 | .BR chown (2) , | |
191 | .BR stat () | |
192 | might return the old | |
193 | .I st_mode | |
194 | together with the new | |
195 | .IR st_uid , | |
196 | or the old | |
197 | .I st_uid | |
198 | together with the new | |
199 | .IR st_mode . | |
200 | ||
da2d9dad | 201 | The |
29de83af | 202 | .I st_dev |
da2d9dad | 203 | field describes the device on which this file resides. |
e9ef777f MK |
204 | (The |
205 | .BR major (3) | |
206 | and | |
207 | .BR minor (3) | |
208 | macros may be useful to decompose the device ID in this field.) | |
da2d9dad MK |
209 | |
210 | The | |
211 | .I st_rdev | |
212 | field describes the device that this file (inode) represents. | |
213 | ||
214 | The | |
fea681da | 215 | .I st_size |
c13182ef MK |
216 | field gives the size of the file (if it is a regular |
217 | file or a symbolic link) in bytes. | |
280ff209 MK |
218 | The size of a symbolic link is the length of the pathname |
219 | it contains, without a terminating null byte. | |
fea681da | 220 | |
da2d9dad | 221 | The |
fea681da | 222 | .I st_blocks |
32f30015 | 223 | field indicates the number of blocks allocated to the file, 512-byte units. |
fea681da | 224 | (This may be smaller than |
eee0a2ec MK |
225 | .IR st_size /512 |
226 | when the file has holes.) | |
da2d9dad MK |
227 | |
228 | The | |
0daa9e92 | 229 | .I st_blksize |
9ee4a2b6 | 230 | field gives the "preferred" blocksize for efficient filesystem I/O. |
fea681da MK |
231 | (Writing to a file in smaller chunks may cause |
232 | an inefficient read-modify-rewrite.) | |
233 | .PP | |
9ee4a2b6 MK |
234 | Not all of the Linux filesystems implement all of the time fields. |
235 | Some filesystem types allow mounting in such a way that file | |
86d89e4c | 236 | and/or directory accesses do not cause an update of the |
fea681da | 237 | .I st_atime |
c13182ef | 238 | field. |
86d89e4c MK |
239 | (See |
240 | .IR noatime , | |
241 | .IR nodiratime , | |
242 | and | |
243 | .I relatime | |
244 | in | |
245 | .BR mount (8), | |
246 | and related information in | |
247 | .BR mount (2).) | |
14adeb6d MK |
248 | In addition, |
249 | .I st_atime | |
250 | is not updated if a file is opened with the | |
251 | .BR O_NOATIME ; | |
252 | see | |
253 | .BR open (2). | |
fea681da MK |
254 | |
255 | The field | |
256 | .I st_atime | |
75b94dc3 | 257 | is changed by file accesses, for example, by |
fea681da MK |
258 | .BR execve (2), |
259 | .BR mknod (2), | |
260 | .BR pipe (2), | |
9af134cd | 261 | .BR utime (2), |
fea681da MK |
262 | and |
263 | .BR read (2) | |
7c93fec0 MK |
264 | (of more than zero bytes). |
265 | Other routines, like | |
fea681da MK |
266 | .BR mmap (2), |
267 | may or may not update | |
268 | .IR st_atime . | |
269 | ||
270 | The field | |
271 | .I st_mtime | |
75b94dc3 | 272 | is changed by file modifications, for example, by |
fea681da MK |
273 | .BR mknod (2), |
274 | .BR truncate (2), | |
9af134cd | 275 | .BR utime (2), |
fea681da MK |
276 | and |
277 | .BR write (2) | |
278 | (of more than zero bytes). | |
279 | Moreover, | |
280 | .I st_mtime | |
281 | of a directory is changed by the creation or deletion of files | |
282 | in that directory. | |
283 | The | |
284 | .I st_mtime | |
285 | field is | |
286 | .I not | |
287 | changed for changes in owner, group, hard link count, or mode. | |
288 | ||
289 | The field | |
290 | .I st_ctime | |
291 | is changed by writing or by setting inode information | |
292 | (i.e., owner, group, link count, mode, etc.). | |
293 | .PP | |
ff3976ce MK |
294 | The following mask values are defined for the file type component of the |
295 | .I st_mode | |
296 | field: | |
297 | .in +4n | |
298 | .TS | |
299 | lB l l. | |
300 | S_IFMT 0170000 bit mask for the file type bit fields | |
301 | ||
302 | S_IFSOCK 0140000 socket | |
303 | S_IFLNK 0120000 symbolic link | |
304 | S_IFREG 0100000 regular file | |
305 | S_IFBLK 0060000 block device | |
306 | S_IFDIR 0040000 directory | |
307 | S_IFCHR 0020000 character device | |
308 | S_IFIFO 0010000 FIFO | |
309 | .TE | |
310 | .in | |
311 | .PP | |
3779bbef MK |
312 | Thus, to test for a regular file (for example), one could write: |
313 | ||
314 | .nf | |
315 | .in +4n | |
316 | stat(pathname, &sb); | |
317 | if ((sb.st_mode & S_IFMT) == S_IFREG) { | |
318 | /* Handle regular file */ | |
319 | } | |
320 | .in | |
321 | .fi | |
322 | .PP | |
323 | Because tests of the above form are common, additional | |
324 | macros are defined by POSIX to allow the test of the file type in | |
168df940 | 325 | .I st_mode |
3779bbef | 326 | to be written more concisely: |
bd191423 | 327 | .RS 4 |
fea681da | 328 | .TP 1.2i |
c91e381d | 329 | .BR S_ISREG (m) |
fea681da MK |
330 | is it a regular file? |
331 | .TP | |
c91e381d | 332 | .BR S_ISDIR (m) |
fea681da MK |
333 | directory? |
334 | .TP | |
c91e381d | 335 | .BR S_ISCHR (m) |
fea681da MK |
336 | character device? |
337 | .TP | |
c91e381d | 338 | .BR S_ISBLK (m) |
fea681da MK |
339 | block device? |
340 | .TP | |
c91e381d | 341 | .BR S_ISFIFO (m) |
da2d9dad | 342 | FIFO (named pipe)? |
fea681da | 343 | .TP |
c91e381d | 344 | .BR S_ISLNK (m) |
77b99918 | 345 | symbolic link? (Not in POSIX.1-1996.) |
fea681da | 346 | .TP |
c91e381d | 347 | .BR S_ISSOCK (m) |
77b99918 | 348 | socket? (Not in POSIX.1-1996.) |
fea681da MK |
349 | .RE |
350 | .PP | |
3779bbef MK |
351 | The preceding code snippet could thus be rewritten as: |
352 | ||
353 | .nf | |
354 | .in +4n | |
355 | stat(pathname, &sb); | |
356 | if (S_ISREG(sb.st_mode)) { | |
357 | /* Handle regular file */ | |
358 | } | |
359 | .in | |
360 | .fi | |
361 | .PP | |
362 | The definitions of most of the above file type test macros | |
cc2b44eb | 363 | are provided if any of the following feature test macros is defined: |
3779bbef MK |
364 | .BR _BSD_SOURCE |
365 | (in glibc 2.19 and earlier), | |
366 | .BR _SVID_SOURCE | |
367 | (in glibc 2.19 and earlier), | |
368 | or | |
369 | .BR _DEFAULT_SOURCE | |
370 | (in glibc 2.20 and later). | |
371 | In addition, definitions of all of the above macros except | |
372 | .BR S_IFSOCK | |
373 | and | |
374 | .BR S_ISSOCK () | |
375 | are provided if | |
376 | .BR _XOPEN_SOURCE | |
377 | is defined. | |
378 | The definition of | |
379 | .BR S_IFSOCK | |
380 | can also be exposed by defining | |
381 | .BR _XOPEN_SOURCE | |
382 | with a value of 500 or greater. | |
383 | ||
384 | The definition of | |
385 | .BR S_ISSOCK () | |
386 | is exposed if any of the following feature test macros is defined: | |
387 | .BR _BSD_SOURCE | |
388 | (in glibc 2.19 and earlier), | |
389 | .BR _DEFAULT_SOURCE | |
390 | (in glibc 2.20 and later), | |
391 | .BR _XOPEN_SOURCE | |
392 | with a value of 500 or greater, or | |
393 | .BR _POSIX_C_SOURCE | |
394 | with a value of 200112L or greater. | |
395 | .PP | |
ff0afc3f | 396 | The following mask values are defined for |
7901c9c3 | 397 | the file mode component of the |
ff0afc3f MK |
398 | .I st_mode |
399 | field: | |
400 | .in +4n | |
401 | .TS | |
402 | lB l l. | |
0d24f47f | 403 | S_ISUID 0004000 set-user-ID bit |
da2d9dad | 404 | S_ISGID 0002000 set-group-ID bit (see below) |
fea681da | 405 | S_ISVTX 0001000 sticky bit (see below) |
ff0afc3f | 406 | |
b0c5363f | 407 | S_IRWXU 00700 owner has read, write and execute permission |
51c6aa6e MK |
408 | S_IRUSR 00400 owner has read permission |
409 | S_IWUSR 00200 owner has write permission | |
410 | S_IXUSR 00100 owner has execute permission | |
ff0afc3f | 411 | |
b0c5363f | 412 | S_IRWXG 00070 group has read, write and execute permission |
51c6aa6e MK |
413 | S_IRGRP 00040 group has read permission |
414 | S_IWGRP 00020 group has write permission | |
415 | S_IXGRP 00010 group has execute permission | |
ff0afc3f | 416 | |
51c6aa6e | 417 | S_IRWXO 00007 T{ |
b0c5363f | 418 | others (not in group) have read, write and execute permission |
a211773a | 419 | T} |
51c6aa6e MK |
420 | S_IROTH 00004 others have read permission |
421 | S_IWOTH 00002 others have write permission | |
422 | S_IXOTH 00001 others have execute permission | |
fea681da | 423 | .TE |
bd191423 | 424 | .in |
fea681da | 425 | .P |
2f0af33b MK |
426 | The set-group-ID bit |
427 | .RB ( S_ISGID ) | |
428 | has several special uses. | |
5c3122b1 | 429 | For a directory, it indicates that BSD semantics is to be used |
fea681da MK |
430 | for that directory: files created there inherit their group ID from |
431 | the directory, not from the effective group ID of the creating process, | |
2f0af33b MK |
432 | and directories created there will also get the |
433 | .B S_ISGID | |
434 | bit set. | |
66ee0c7e | 435 | For a file that does not have the group execution bit |
2f0af33b MK |
436 | .RB ( S_IXGRP ) |
437 | set, | |
da2d9dad | 438 | the set-group-ID bit indicates mandatory file/record locking. |
fea681da | 439 | .P |
2d986c92 | 440 | The sticky bit |
2f0af33b MK |
441 | .RB ( S_ISVTX ) |
442 | on a directory means that a file | |
fea681da MK |
443 | in that directory can be renamed or deleted only by the owner |
444 | of the file, by the owner of the directory, and by a privileged | |
445 | process. | |
40084043 MK |
446 | .\" |
447 | .\" | |
1fef0fa3 | 448 | .SS fstatat() |
40084043 MK |
449 | The |
450 | .BR fstatat () | |
451 | system call operates in exactly the same way as | |
cadd38ba | 452 | .BR stat (), |
40084043 MK |
453 | except for the differences described here. |
454 | ||
455 | If the pathname given in | |
456 | .I pathname | |
457 | is relative, then it is interpreted relative to the directory | |
458 | referred to by the file descriptor | |
459 | .I dirfd | |
460 | (rather than relative to the current working directory of | |
461 | the calling process, as is done by | |
cadd38ba | 462 | .BR stat () |
40084043 MK |
463 | for a relative pathname). |
464 | ||
465 | If | |
466 | .I pathname | |
467 | is relative and | |
468 | .I dirfd | |
469 | is the special value | |
470 | .BR AT_FDCWD , | |
471 | then | |
472 | .I pathname | |
473 | is interpreted relative to the current working | |
474 | directory of the calling process (like | |
cadd38ba | 475 | .BR stat ()). |
40084043 MK |
476 | |
477 | If | |
478 | .I pathname | |
479 | is absolute, then | |
480 | .I dirfd | |
481 | is ignored. | |
482 | ||
483 | .I flags | |
484 | can either be 0, or include one or more of the following flags ORed: | |
485 | .TP | |
486 | .BR AT_EMPTY_PATH " (since Linux 2.6.39)" | |
487 | .\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d | |
488 | If | |
489 | .I pathname | |
490 | is an empty string, operate on the file referred to by | |
491 | .IR dirfd | |
492 | (which may have been obtained using the | |
493 | .BR open (2) | |
494 | .B O_PATH | |
495 | flag). | |
a6fcbdf8 MK |
496 | If |
497 | .I dirfd | |
498 | is | |
499 | .BR AT_FDCWD , | |
500 | the call operates on the current working directory. | |
40084043 MK |
501 | In this case, |
502 | .I dirfd | |
503 | can refer to any type of file, not just a directory. | |
504 | This flag is Linux-specific; define | |
505 | .B _GNU_SOURCE | |
506 | .\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed | |
507 | to obtain its definition. | |
508 | .TP | |
509 | .BR AT_NO_AUTOMOUNT " (since Linux 2.6.38)" | |
510 | Don't automount the terminal ("basename") component of | |
511 | .I pathname | |
512 | if it is a directory that is an automount point. | |
513 | This allows the caller to gather attributes of an automount point | |
514 | (rather than the location it would mount). | |
515 | This flag can be used in tools that scan directories | |
516 | to prevent mass-automounting of a directory of automount points. | |
517 | The | |
518 | .B AT_NO_AUTOMOUNT | |
519 | flag has no effect if the mount point has already been mounted over. | |
520 | This flag is Linux-specific; define | |
521 | .B _GNU_SOURCE | |
522 | .\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed | |
523 | to obtain its definition. | |
524 | .TP | |
525 | .B AT_SYMLINK_NOFOLLOW | |
526 | If | |
527 | .I pathname | |
528 | is a symbolic link, do not dereference it: | |
529 | instead return information about the link itself, like | |
cadd38ba | 530 | .BR lstat (). |
40084043 MK |
531 | (By default, |
532 | .BR fstatat () | |
533 | dereferences symbolic links, like | |
cadd38ba | 534 | .BR stat ().) |
40084043 MK |
535 | .PP |
536 | See | |
537 | .BR openat (2) | |
538 | for an explanation of the need for | |
539 | .BR fstatat (). | |
47297adb | 540 | .SH RETURN VALUE |
c13182ef MK |
541 | On success, zero is returned. |
542 | On error, \-1 is returned, and | |
fea681da MK |
543 | .I errno |
544 | is set appropriately. | |
545 | .SH ERRORS | |
546 | .TP | |
547 | .B EACCES | |
548 | Search permission is denied for one of the directories | |
549 | in the path prefix of | |
66cbeaf4 | 550 | .IR pathname . |
fea681da | 551 | (See also |
ad7cc990 | 552 | .BR path_resolution (7).) |
fea681da MK |
553 | .TP |
554 | .B EBADF | |
d3b03141 | 555 | .I fd |
fea681da MK |
556 | is bad. |
557 | .TP | |
558 | .B EFAULT | |
559 | Bad address. | |
560 | .TP | |
561 | .B ELOOP | |
562 | Too many symbolic links encountered while traversing the path. | |
563 | .TP | |
564 | .B ENAMETOOLONG | |
66cbeaf4 | 565 | .I pathname |
c066b169 | 566 | is too long. |
fea681da MK |
567 | .TP |
568 | .B ENOENT | |
5cf0b3b4 | 569 | A component of |
66cbeaf4 | 570 | .I pathname |
5cf0b3b4 | 571 | does not exist, or |
66cbeaf4 | 572 | .I pathname |
5cf0b3b4 | 573 | is an empty string. |
fea681da MK |
574 | .TP |
575 | .B ENOMEM | |
75b94dc3 | 576 | Out of memory (i.e., kernel memory). |
fea681da MK |
577 | .TP |
578 | .B ENOTDIR | |
94ea1e9d | 579 | A component of the path prefix of |
66cbeaf4 | 580 | .I pathname |
5cf0b3b4 | 581 | is not a directory. |
9dcc4605 MK |
582 | .TP |
583 | .B EOVERFLOW | |
66cbeaf4 | 584 | .I pathname |
fec75159 SP |
585 | or |
586 | .I fd | |
587 | refers to a file whose size, inode number, | |
588 | or number of blocks cannot be represented in, respectively, the types | |
589 | .IR off_t , | |
590 | .IR ino_t , | |
591 | or | |
592 | .IR blkcnt_t . | |
593 | This error can occur when, for example, | |
594 | an application compiled on a 32-bit platform without | |
5e4dc269 | 595 | .I -D_FILE_OFFSET_BITS=64 |
9dcc4605 MK |
596 | calls |
597 | .BR stat () | |
598 | on a file whose size exceeds | |
4d69ed2e | 599 | .I (1<<31)-1 |
fec75159 | 600 | bytes. |
40084043 | 601 | .PP |
40084043 MK |
602 | The following additional errors can occur for |
603 | .BR fstatat (): | |
604 | .TP | |
605 | .B EBADF | |
606 | .I dirfd | |
607 | is not a valid file descriptor. | |
608 | .TP | |
609 | .B EINVAL | |
610 | Invalid flag specified in | |
611 | .IR flags . | |
612 | .TP | |
613 | .B ENOTDIR | |
614 | .I pathname | |
615 | is relative and | |
616 | .I dirfd | |
617 | is a file descriptor referring to a file other than a directory. | |
618 | .SH VERSIONS | |
619 | .BR fstatat () | |
620 | was added to Linux in kernel 2.6.16; | |
621 | library support was added to glibc in version 2.4. | |
47297adb | 622 | .SH CONFORMING TO |
40084043 MK |
623 | .BR stat (), |
624 | .BR fstat (), | |
625 | .BR lstat (): | |
282daba9 | 626 | SVr4, 4.3BSD, POSIX.1-2001, POSIX.1.2008. |
97c1eac8 MK |
627 | .\" SVr4 documents additional |
628 | .\" .BR fstat () | |
629 | .\" error conditions EINTR, ENOLINK, and EOVERFLOW. SVr4 | |
630 | .\" documents additional | |
631 | .\" .BR stat () | |
632 | .\" and | |
633 | .\" .BR lstat () | |
634 | .\" error conditions EINTR, EMULTIHOP, ENOLINK, and EOVERFLOW. | |
635 | ||
40084043 MK |
636 | .BR fstatat (): |
637 | POSIX.1-2008. | |
40084043 | 638 | |
d3e8b141 MK |
639 | According to POSIX.1-2001, |
640 | .BR lstat () | |
641 | on a symbolic link need return valid information only in the | |
642 | .I st_size | |
643 | field and the file-type component of the | |
644 | .IR st_mode | |
645 | field of the | |
646 | .IR stat | |
647 | structure. | |
a03c016c | 648 | POSIX.1-2008 tightens the specification, requiring |
d3e8b141 | 649 | .BR lstat () |
7901c9c3 | 650 | to return valid information in all fields except the mode bits in |
d3e8b141 MK |
651 | .IR st_mode . |
652 | ||
fea681da MK |
653 | Use of the |
654 | .I st_blocks | |
655 | and | |
656 | .I st_blksize | |
c13182ef MK |
657 | fields may be less portable. |
658 | (They were introduced in BSD. | |
659 | The interpretation differs between systems, | |
660 | and possibly on a single system when NFS mounts are involved.) | |
34c909ac MK |
661 | If you need to obtain the definition of the |
662 | .IR blkcnt_t | |
663 | or | |
664 | .IR blksize_t | |
665 | types from | |
666 | .IR <sys/stat.h> , | |
667 | then define | |
668 | .BR _XOPEN_SOURCE | |
669 | with the value 500 or greater (before including | |
670 | .I any | |
671 | header files). | |
fea681da | 672 | .LP |
beb0ebc8 | 673 | POSIX.1-1990 did not describe the |
66ee0c7e MK |
674 | .BR S_IFMT , |
675 | .BR S_IFSOCK , | |
676 | .BR S_IFLNK , | |
677 | .BR S_IFREG , | |
c91e381d | 678 | .BR S_IFBLK , |
66ee0c7e MK |
679 | .BR S_IFDIR , |
680 | .BR S_IFCHR , | |
681 | .BR S_IFIFO , | |
0daa9e92 | 682 | .B S_ISVTX |
beb0ebc8 | 683 | constants, but instead demanded the use of |
c91e381d MK |
684 | the macros |
685 | .BR S_ISDIR (), | |
f78ed33a | 686 | and so on. |
beb0ebc8 MK |
687 | The |
688 | .BR S_IF* | |
318c8142 | 689 | constants are present in POSIX.1-2001 and later. |
beb0ebc8 | 690 | |
1274071a | 691 | The |
c91e381d | 692 | .BR S_ISLNK () |
1274071a | 693 | and |
c91e381d | 694 | .BR S_ISSOCK () |
1274071a | 695 | macros are not in |
97c1eac8 MK |
696 | POSIX.1-1996, but both are present in POSIX.1-2001; |
697 | the former is from SVID 4, the latter from SUSv2. | |
fea681da | 698 | .LP |
b4112efb | 699 | UNIX\ V7 (and later systems) had |
66ee0c7e MK |
700 | .BR S_IREAD , |
701 | .BR S_IWRITE , | |
c91e381d MK |
702 | .BR S_IEXEC , |
703 | where POSIX | |
66ee0c7e MK |
704 | prescribes the synonyms |
705 | .BR S_IRUSR , | |
706 | .BR S_IWUSR , | |
c91e381d | 707 | .BR S_IXUSR . |
73d8cece | 708 | .SS Other systems |
fea681da | 709 | Values that have been (or are) in use on various systems: |
77b99918 | 710 | .ad l |
fea681da MK |
711 | .TS |
712 | l l l l l. | |
713 | hex name ls octal description | |
714 | f000 S_IFMT 170000 mask for file type | |
77b99918 BIG |
715 | 0000 000000 T{ |
716 | SCO out-of-service inode; BSD unknown type; SVID-v2 and XPG2 | |
717 | have both 0 and 0100000 for ordinary file | |
718 | T} | |
da2d9dad | 719 | 1000 S_IFIFO p| 010000 FIFO (named pipe) |
fea681da MK |
720 | 2000 S_IFCHR c 020000 character special (V7) |
721 | 3000 S_IFMPC 030000 multiplexed character special (V7) | |
722 | 4000 S_IFDIR d/ 040000 directory (V7) | |
77b99918 BIG |
723 | 5000 S_IFNAM 050000 T{ |
724 | XENIX named special file with two subtypes, distinguished by | |
725 | \fIst_rdev\fP values 1, 2 | |
726 | T} | |
fea681da MK |
727 | 0001 S_INSEM s 000001 XENIX semaphore subtype of IFNAM |
728 | 0002 S_INSHD m 000002 XENIX shared data subtype of IFNAM | |
729 | 6000 S_IFBLK b 060000 block special (V7) | |
730 | 7000 S_IFMPB 070000 multiplexed block special (V7) | |
731 | 8000 S_IFREG - 100000 regular (V7) | |
732 | 9000 S_IFCMP 110000 VxFS compressed | |
733 | 9000 S_IFNWK n 110000 network special (HP-UX) | |
734 | a000 S_IFLNK l@ 120000 symbolic link (BSD) | |
77b99918 | 735 | b000 S_IFSHAD 130000 T{ |
7fac88a9 | 736 | Solaris shadow inode for ACL (not seen by user space) |
77b99918 | 737 | T} |
fea681da MK |
738 | c000 S_IFSOCK s= 140000 socket (BSD; also "S_IFSOC" on VxFS) |
739 | d000 S_IFDOOR D> 150000 Solaris door | |
740 | e000 S_IFWHT w% 160000 BSD whiteout (not used for inode) | |
77b99918 BIG |
741 | 0200 S_ISVTX 001000 T{ |
742 | sticky bit: save swapped text even after use (V7) | |
743 | .br | |
744 | reserved (SVID-v2) | |
745 | .br | |
746 | On nondirectories: don't cache this file (SunOS) | |
747 | .br | |
748 | On directories: restricted deletion flag (SVID-v4.2) | |
749 | T} | |
750 | 0400 S_ISGID 002000 T{ | |
751 | set-group-ID on execution (V7) | |
752 | .br | |
753 | for directories: use BSD semantics for propagation of GID | |
754 | T} | |
755 | 0400 S_ENFMT 002000 T{ | |
756 | System V file locking enforcement (shared with S_ISGID) | |
757 | T} | |
da2d9dad | 758 | 0800 S_ISUID 004000 set-user-ID on execution (V7) |
77b99918 BIG |
759 | 0800 S_CDF 004000 T{ |
760 | directory is a context dependent file (HP-UX) | |
761 | T} | |
fea681da | 762 | .TE |
77b99918 | 763 | .ad |
fea681da MK |
764 | |
765 | A sticky command appeared in Version 32V AT&T UNIX. | |
2b2581ee | 766 | .SH NOTES |
1ef5b280 MK |
767 | On Linux, |
768 | .BR lstat () | |
769 | will generally not trigger automounter action, whereas | |
770 | .BR stat () | |
771 | will (but see | |
772 | .BR fstatat (2)). | |
773 | ||
774 | For most files under the | |
775 | .I /proc | |
776 | directory, | |
777 | .BR stat () | |
778 | does not return the file size in the | |
779 | .I st_size | |
780 | field; instead the field is returned with the value 0. | |
781 | .SS Timestamp fields | |
e9e9e87e MK |
782 | Older kernels and older standards did not support nanosecond timestamp |
783 | fields. | |
b8efc3ed | 784 | Instead, there were three timestamp |
e9e9e87e MK |
785 | .RI fields\(em st_atime , |
786 | .IR st_mtime , | |
787 | and | |
788 | .IR st_ctime \(emtyped | |
b8efc3ed | 789 | as |
e9e9e87e MK |
790 | .IR time_t |
791 | that recorded timestamps with one-second precision. | |
1ef5b280 | 792 | |
2b2581ee MK |
793 | Since kernel 2.5.48, the |
794 | .I stat | |
f5935752 | 795 | structure supports nanosecond resolution for the three file timestamp fields. |
e9e9e87e MK |
796 | The nanosecond components of each timestamp are available |
797 | via names of the form | |
f5935752 | 798 | .IR st_atim.tv_nsec |
db4e96b7 MK |
799 | if the |
800 | .B _BSD_SOURCE | |
801 | or | |
802 | .B _SVID_SOURCE | |
f5935752 | 803 | feature test macro is defined. |
e9e9e87e MK |
804 | Nanosecond timestamps are nowadays standardized, |
805 | starting with POSIX.1-2008, and, starting with version 2.12, | |
806 | glibc also exposes the nanosecond component names if | |
f5935752 MK |
807 | .BR _POSIX_C_SOURCE |
808 | is defined with the value 200809L or greater, or | |
809 | .BR _XOPEN_SOURCE | |
810 | is defined with the value 700 or greater. | |
811 | If none of the aforementioned macros are defined, | |
812 | then the nanosecond values are exposed with names of the form | |
813 | .IR st_atimensec . | |
1ef5b280 | 814 | |
96f92a7c MK |
815 | Nanosecond timestamps are supported on XFS, JFS, Btrfs, and |
816 | ext4 (since Linux 2.6.23). | |
817 | .\" commit ef7f38359ea8b3e9c7f2cae9a4d4935f55ca9e80 | |
c2033cfe | 818 | Nanosecond timestamps are not supported in ext2, ext3, and Reiserfs. |
1ef5b280 MK |
819 | On filesystems that do not support subsecond timestamps, |
820 | the nanosecond fields are returned with the value 0. | |
1fbe05e0 | 821 | .SS C library/kernel ABI differences |
b8f9d9dd MK |
822 | Over time, increases in the size of the |
823 | .I stat | |
0c8dd254 | 824 | structure have led to three successive versions of |
b8f9d9dd MK |
825 | .BR stat (): |
826 | .IR sys_stat () | |
827 | (slot | |
828 | .IR __NR_oldstat ), | |
829 | .IR sys_newstat () | |
830 | (slot | |
831 | .IR __NR_stat ), | |
832 | and | |
0daa9e92 | 833 | .I sys_stat64() |
a39f2f4d | 834 | (slot |
94971420 MK |
835 | .IR __NR_stat64 ) |
836 | on 32-bit platforms such as i386. | |
837 | The first two versions were already present in Linux 1.0 | |
838 | (albeit with different names); | |
cd358be3 | 839 | .\" See include/asm-i386/stat.h in the Linux 2.4 source code for the |
94971420 MK |
840 | .\" various versions of the structure definitions |
841 | the last was added in Linux 2.4. | |
842 | Similar remarks apply for | |
843 | .BR fstat () | |
844 | and | |
845 | .BR lstat (). | |
846 | ||
847 | The kernel-internal versions of the | |
848 | .I stat | |
849 | structure dealt with by the different versions are, respectively: | |
850 | .RS | |
851 | .TP | |
852 | .IR __old_kernel_stat | |
853 | The original structure, with rather narrow fields, and no padding. | |
854 | .TP | |
855 | .IR stat | |
856 | Larger | |
857 | .I st_ino | |
858 | field and padding added to various parts of the structure to | |
859 | allow for future expansion. | |
860 | .TP | |
861 | .IR stat64 | |
862 | Even larger | |
863 | .I st_ino | |
864 | field, | |
865 | larger | |
866 | .I st_uid | |
867 | and | |
868 | .I st_gid | |
869 | fields to accommodate the Linux-2.4 expansion of UIDs and GIDs to 32 bits, | |
870 | and various other enlarged fields and further padding in the structure. | |
871 | (Various padding bytes were eventually consumed in Linux 2.6, | |
872 | with the advent of 32-bit device IDs and nanosecond components | |
873 | for the timestamp fields.) | |
874 | .RE | |
875 | .PP | |
d28a0b77 | 876 | The glibc |
b8f9d9dd | 877 | .BR stat () |
d28a0b77 | 878 | wrapper function hides these details from applications, |
6f1a1e61 MK |
879 | invoking the most recent version of the system call provided by the kernel, |
880 | and repacking the returned information if required for old binaries. | |
8179def1 MK |
881 | .\" |
882 | .\" A note from Andries Brouwer, July 2007 | |
e0bf9127 MK |
883 | .\" |
884 | .\" > Is the story not rather more complicated for some calls like | |
8179def1 | 885 | .\" > stat(2)? |
e0bf9127 | 886 | .\" |
8179def1 | 887 | .\" Yes and no, mostly no. See /usr/include/sys/stat.h . |
e0bf9127 | 888 | .\" |
8179def1 MK |
889 | .\" The idea is here not so much that syscalls change, but that |
890 | .\" the definitions of struct stat and of the types dev_t and mode_t change. | |
891 | .\" This means that libc (even if it does not call the kernel | |
892 | .\" but only calls some internal function) must know what the | |
893 | .\" format of dev_t or of struct stat is. | |
894 | .\" The communication between the application and libc goes via | |
895 | .\" the include file <sys/stat.h> that defines a _STAT_VER and | |
896 | .\" _MKNOD_VER describing the layout of the data that user space | |
897 | .\" uses. Each (almost each) occurrence of stat() is replaced by | |
898 | .\" an occurrence of xstat() where the first parameter of xstat() | |
899 | .\" is this version number _STAT_VER. | |
e0bf9127 | 900 | .\" |
8179def1 MK |
901 | .\" Now, also the definitions used by the kernel change. |
902 | .\" But glibc copes with this in the standard way, and the | |
903 | .\" struct stat as returned by the kernel is repacked into | |
904 | .\" the struct stat as expected by the application. | |
905 | .\" Thus, _STAT_VER and this setup cater for the application-libc | |
906 | .\" interface, rather than the libc-kernel interface. | |
e0bf9127 | 907 | .\" |
8179def1 | 908 | .\" (Note that the details depend on gcc being used as c compiler.) |
40084043 | 909 | |
94971420 MK |
910 | On modern 64-bit systems, life is simpler: there is a single |
911 | .BR stat () | |
912 | system call and the kernel deals with a | |
913 | .I stat | |
914 | structure that contains fields of a sufficient size. | |
915 | ||
40084043 MK |
916 | The underlying system call employed by the glibc |
917 | .BR fstatat () | |
918 | wrapper function is actually called | |
cad6df32 MK |
919 | .BR fstatat64 () |
920 | or, on some architectures, | |
921 | .\" strace(1) shows the name "newfstatat" on x86-64 | |
922 | .BR newfstatat (). | |
bc7ff20e | 923 | .SH EXAMPLE |
988db661 | 924 | The following program calls |
2777b1ca | 925 | .BR stat () |
bc7ff20e MK |
926 | and displays selected fields in the returned |
927 | .I stat | |
928 | structure. | |
929 | .nf | |
930 | ||
931 | #include <sys/types.h> | |
932 | #include <sys/stat.h> | |
933 | #include <time.h> | |
934 | #include <stdio.h> | |
988db661 | 935 | #include <stdlib.h> |
bc7ff20e MK |
936 | |
937 | int | |
938 | main(int argc, char *argv[]) | |
939 | { | |
940 | struct stat sb; | |
941 | ||
942 | if (argc != 2) { | |
943 | fprintf(stderr, "Usage: %s <pathname>\\n", argv[0]); | |
944 | exit(EXIT_FAILURE); | |
945 | } | |
946 | ||
29059a65 | 947 | if (stat(argv[1], &sb) == \-1) { |
bc7ff20e | 948 | perror("stat"); |