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1 | '\" t |
2 | .\" Hey Emacs! This file is -*- nroff -*- source. | |
3 | .\" | |
4 | .\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992 | |
5 | .\" Parts Copyright (c) 1995 Nicolai Langfeldt (janl@ifi.uio.no), 1/1/95 | |
bc7ff20e | 6 | .\" and Copyright (c) 2007 Michael Kerrisk <mtk-manpages@gmx.net> |
fea681da MK |
7 | .\" |
8 | .\" Permission is granted to make and distribute verbatim copies of this | |
9 | .\" manual provided the copyright notice and this permission notice are | |
10 | .\" preserved on all copies. | |
11 | .\" | |
12 | .\" Permission is granted to copy and distribute modified versions of this | |
13 | .\" manual under the conditions for verbatim copying, provided that the | |
14 | .\" entire resulting derived work is distributed under the terms of a | |
15 | .\" permission notice identical to this one. | |
c13182ef | 16 | .\" |
fea681da MK |
17 | .\" Since the Linux kernel and libraries are constantly changing, this |
18 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
19 | .\" responsibility for errors or omissions, or for damages resulting from | |
20 | .\" the use of the information contained herein. The author(s) may not | |
21 | .\" have taken the same level of care in the production of this manual, | |
22 | .\" which is licensed free of charge, as they might when working | |
23 | .\" professionally. | |
c13182ef | 24 | .\" |
fea681da MK |
25 | .\" Formatted or processed versions of this manual, if unaccompanied by |
26 | .\" the source, must acknowledge the copyright and authors of this work. | |
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 | |
305a0578 | 36 | .\" Modified 2004-06-23 by Michael Kerrisk <mtk-manpages@gmx.net> |
bc7ff20e | 37 | .\" 2007-06-08 mtk: Added example program |
c13182ef | 38 | .\" |
bc7ff20e | 39 | .TH STAT 2 2007-06-08 "Linux" "Linux Programmer's Manual" |
fea681da MK |
40 | .SH NAME |
41 | stat, fstat, lstat \- get file status | |
42 | .SH SYNOPSIS | |
43 | .B #include <sys/types.h> | |
44 | .br | |
45 | .B #include <sys/stat.h> | |
46 | .br | |
47 | .B #include <unistd.h> | |
48 | .sp | |
da2d9dad | 49 | .BI "int stat(const char *" path ", struct stat *" buf ); |
fea681da MK |
50 | .br |
51 | .BI "int fstat(int " filedes ", struct stat *" buf ); | |
52 | .br | |
da2d9dad | 53 | .BI "int lstat(const char *" path ", struct stat *" buf ); |
fea681da MK |
54 | .SH DESCRIPTION |
55 | .PP | |
da2d9dad MK |
56 | These functions return information about a file. |
57 | No permissions are required on the file itself, but \(em in the case of | |
58 | .BR stat () | |
c13182ef | 59 | and |
da2d9dad MK |
60 | .BR lstat () |
61 | \(em | |
62 | execute (search) permission is required on all of the directories in | |
63 | .I path | |
64 | that lead to the file. | |
fea681da | 65 | .PP |
da2d9dad | 66 | .BR stat () |
c13182ef | 67 | stats the file pointed to by |
da2d9dad | 68 | .I path |
fea681da MK |
69 | and fills in |
70 | .IR buf . | |
71 | ||
da2d9dad | 72 | .BR lstat () |
fea681da | 73 | is identical to |
da2d9dad MK |
74 | .BR stat (), |
75 | except that if | |
76 | .I path | |
77 | is a symbolic link, then the link itself is stat-ed, | |
fea681da MK |
78 | not the file that it refers to. |
79 | ||
da2d9dad | 80 | .BR fstat () |
fea681da | 81 | is identical to |
da2d9dad MK |
82 | .BR stat (), |
83 | except that the file to be stat-ed is specified by the file descriptor | |
84 | .IR filedes . | |
fea681da | 85 | .PP |
da2d9dad | 86 | All of these system calls return a |
fea681da MK |
87 | .I stat |
88 | structure, which contains the following fields: | |
89 | .PP | |
5ae873ff | 90 | .RS 0.25i |
fea681da MK |
91 | .nf |
92 | struct stat { | |
da2d9dad MK |
93 | dev_t st_dev; /* ID of device containing file */ |
94 | ino_t st_ino; /* inode number */ | |
5ae873ff MK |
95 | mode_t st_mode; /* protection */ |
96 | nlink_t st_nlink; /* number of hard links */ | |
97 | uid_t st_uid; /* user ID of owner */ | |
98 | gid_t st_gid; /* group ID of owner */ | |
da2d9dad | 99 | dev_t st_rdev; /* device ID (if special file) */ |
5ae873ff MK |
100 | off_t st_size; /* total size, in bytes */ |
101 | blksize_t st_blksize; /* blocksize for filesystem I/O */ | |
102 | blkcnt_t st_blocks; /* number of blocks allocated */ | |
103 | time_t st_atime; /* time of last access */ | |
104 | time_t st_mtime; /* time of last modification */ | |
105 | time_t st_ctime; /* time of last status change */ | |
fea681da MK |
106 | }; |
107 | .fi | |
108 | .RE | |
109 | .PP | |
da2d9dad | 110 | The |
29de83af | 111 | .I st_dev |
da2d9dad MK |
112 | field describes the device on which this file resides. |
113 | ||
114 | The | |
115 | .I st_rdev | |
116 | field describes the device that this file (inode) represents. | |
117 | ||
118 | The | |
fea681da | 119 | .I st_size |
c13182ef MK |
120 | field gives the size of the file (if it is a regular |
121 | file or a symbolic link) in bytes. | |
da2d9dad | 122 | The size of a symlink is the length of the pathname |
28d88c17 | 123 | it contains, without a trailing null byte. |
fea681da | 124 | |
da2d9dad | 125 | The |
fea681da | 126 | .I st_blocks |
32f30015 | 127 | field indicates the number of blocks allocated to the file, 512-byte units. |
fea681da | 128 | (This may be smaller than |
da2d9dad MK |
129 | .IR st_size /512, |
130 | for example, when the file has holes.) | |
131 | ||
132 | The | |
fea681da | 133 | .IR st_blksize |
da2d9dad | 134 | field gives the "preferred" blocksize for efficient file system I/O. |
fea681da MK |
135 | (Writing to a file in smaller chunks may cause |
136 | an inefficient read-modify-rewrite.) | |
137 | .PP | |
138 | Not all of the Linux filesystems implement all of the time fields. | |
139 | Some file system types allow mounting in such a way that file | |
140 | accesses do not cause an update of the | |
141 | .I st_atime | |
c13182ef MK |
142 | field. |
143 | (See `noatime' in | |
fea681da MK |
144 | .BR mount (8).) |
145 | ||
146 | The field | |
147 | .I st_atime | |
148 | is changed by file accesses, e.g. by | |
149 | .BR execve (2), | |
150 | .BR mknod (2), | |
151 | .BR pipe (2), | |
152 | .BR utime (2) | |
153 | and | |
154 | .BR read (2) | |
7c93fec0 MK |
155 | (of more than zero bytes). |
156 | Other routines, like | |
fea681da MK |
157 | .BR mmap (2), |
158 | may or may not update | |
159 | .IR st_atime . | |
160 | ||
161 | The field | |
162 | .I st_mtime | |
163 | is changed by file modifications, e.g. by | |
164 | .BR mknod (2), | |
165 | .BR truncate (2), | |
166 | .BR utime (2) | |
167 | and | |
168 | .BR write (2) | |
169 | (of more than zero bytes). | |
170 | Moreover, | |
171 | .I st_mtime | |
172 | of a directory is changed by the creation or deletion of files | |
173 | in that directory. | |
174 | The | |
175 | .I st_mtime | |
176 | field is | |
177 | .I not | |
178 | changed for changes in owner, group, hard link count, or mode. | |
179 | ||
180 | The field | |
181 | .I st_ctime | |
182 | is changed by writing or by setting inode information | |
183 | (i.e., owner, group, link count, mode, etc.). | |
184 | .PP | |
168df940 MK |
185 | The following POSIX macros are defined to check the file type using the |
186 | .I st_mode | |
187 | field: | |
fea681da MK |
188 | .RS |
189 | .TP 1.2i | |
190 | S_ISREG(m) | |
191 | is it a regular file? | |
192 | .TP | |
193 | S_ISDIR(m) | |
194 | directory? | |
195 | .TP | |
196 | S_ISCHR(m) | |
197 | character device? | |
198 | .TP | |
199 | S_ISBLK(m) | |
200 | block device? | |
201 | .TP | |
202 | S_ISFIFO(m) | |
da2d9dad | 203 | FIFO (named pipe)? |
fea681da MK |
204 | .TP |
205 | S_ISLNK(m) | |
206 | symbolic link? (Not in POSIX.1-1996.) | |
207 | .TP | |
208 | S_ISSOCK(m) | |
209 | socket? (Not in POSIX.1-1996.) | |
210 | .RE | |
211 | .PP | |
212 | The following flags are defined for the | |
213 | .I st_mode | |
214 | field: | |
fea681da MK |
215 | .TS |
216 | l l l. | |
217 | S_IFMT 0170000 bitmask for the file type bitfields | |
218 | S_IFSOCK 0140000 socket | |
219 | S_IFLNK 0120000 symbolic link | |
220 | S_IFREG 0100000 regular file | |
221 | S_IFBLK 0060000 block device | |
222 | S_IFDIR 0040000 directory | |
223 | S_IFCHR 0020000 character device | |
da2d9dad | 224 | S_IFIFO 0010000 FIFO |
fea681da | 225 | S_ISUID 0004000 set UID bit |
da2d9dad | 226 | S_ISGID 0002000 set-group-ID bit (see below) |
fea681da MK |
227 | S_ISVTX 0001000 sticky bit (see below) |
228 | S_IRWXU 00700 mask for file owner permissions | |
229 | S_IRUSR 00400 owner has read permission | |
230 | S_IWUSR 00200 owner has write permission | |
231 | S_IXUSR 00100 owner has execute permission | |
232 | S_IRWXG 00070 mask for group permissions | |
233 | S_IRGRP 00040 group has read permission | |
234 | S_IWGRP 00020 group has write permission | |
235 | S_IXGRP 00010 group has execute permission | |
236 | S_IRWXO 00007 mask for permissions for others (not in group) | |
237 | S_IROTH 00004 others have read permission | |
704a18f0 | 238 | S_IWOTH 00002 others have write permission |
fea681da MK |
239 | S_IXOTH 00001 others have execute permission |
240 | .TE | |
241 | .P | |
da2d9dad | 242 | The set-group-ID bit (S_ISGID) has several special uses. |
fea681da MK |
243 | For a directory it indicates that BSD semantics is to be used |
244 | for that directory: files created there inherit their group ID from | |
245 | the directory, not from the effective group ID of the creating process, | |
246 | and directories created there will also get the S_ISGID bit set. | |
247 | For a file that does not have the group execution bit (S_IXGRP) set, | |
da2d9dad | 248 | the set-group-ID bit indicates mandatory file/record locking. |
fea681da MK |
249 | .P |
250 | The `sticky' bit (S_ISVTX) on a directory means that a file | |
251 | in that directory can be renamed or deleted only by the owner | |
252 | of the file, by the owner of the directory, and by a privileged | |
253 | process. | |
254 | .SH "RETURN VALUE" | |
c13182ef MK |
255 | On success, zero is returned. |
256 | On error, \-1 is returned, and | |
fea681da MK |
257 | .I errno |
258 | is set appropriately. | |
259 | .SH ERRORS | |
260 | .TP | |
261 | .B EACCES | |
262 | Search permission is denied for one of the directories | |
263 | in the path prefix of | |
da2d9dad | 264 | .IR path . |
fea681da | 265 | (See also |
ad7cc990 | 266 | .BR path_resolution (7).) |
fea681da MK |
267 | .TP |
268 | .B EBADF | |
269 | .I filedes | |
270 | is bad. | |
271 | .TP | |
272 | .B EFAULT | |
273 | Bad address. | |
274 | .TP | |
275 | .B ELOOP | |
276 | Too many symbolic links encountered while traversing the path. | |
277 | .TP | |
278 | .B ENAMETOOLONG | |
279 | File name too long. | |
280 | .TP | |
281 | .B ENOENT | |
282 | A component of the path | |
da2d9dad | 283 | .I path |
fea681da MK |
284 | does not exist, or the path is an empty string. |
285 | .TP | |
286 | .B ENOMEM | |
287 | Out of memory (i.e. kernel memory). | |
288 | .TP | |
289 | .B ENOTDIR | |
290 | A component of the path is not a directory. | |
291 | .SH "CONFORMING TO" | |
a7fadb55 | 292 | These system calls conform to SVr4, 4.3BSD, POSIX.1-2001. |
97c1eac8 MK |
293 | .\" SVr4 documents additional |
294 | .\" .BR fstat () | |
295 | .\" error conditions EINTR, ENOLINK, and EOVERFLOW. SVr4 | |
296 | .\" documents additional | |
297 | .\" .BR stat () | |
298 | .\" and | |
299 | .\" .BR lstat () | |
300 | .\" error conditions EINTR, EMULTIHOP, ENOLINK, and EOVERFLOW. | |
301 | ||
fea681da MK |
302 | Use of the |
303 | .I st_blocks | |
304 | and | |
305 | .I st_blksize | |
c13182ef MK |
306 | fields may be less portable. |
307 | (They were introduced in BSD. | |
308 | The interpretation differs between systems, | |
309 | and possibly on a single system when NFS mounts are involved.) | |
fea681da MK |
310 | .LP |
311 | POSIX does not describe the S_IFMT, S_IFSOCK, S_IFLNK, S_IFREG, S_IFBLK, | |
312 | S_IFDIR, S_IFCHR, S_IFIFO, S_ISVTX bits, but instead demands the use of | |
c13182ef | 313 | the macros S_ISDIR(), etc. |
97c1eac8 MK |
314 | The S_ISLNK and S_ISSOCK macros are not in |
315 | POSIX.1-1996, but both are present in POSIX.1-2001; | |
316 | the former is from SVID 4, the latter from SUSv2. | |
fea681da MK |
317 | .LP |
318 | Unix V7 (and later systems) had S_IREAD, S_IWRITE, S_IEXEC, where POSIX | |
319 | prescribes the synonyms S_IRUSR, S_IWUSR, S_IXUSR. | |
042bae96 | 320 | .SS "Other Systems" |
fea681da | 321 | Values that have been (or are) in use on various systems: |
fea681da MK |
322 | .TS |
323 | l l l l l. | |
324 | hex name ls octal description | |
325 | f000 S_IFMT 170000 mask for file type | |
326 | 0000 000000 SCO out-of-service inode, BSD unknown type | |
327 | SVID-v2 and XPG2 have both 0 and 0100000 for ordinary file | |
da2d9dad | 328 | 1000 S_IFIFO p| 010000 FIFO (named pipe) |
fea681da MK |
329 | 2000 S_IFCHR c 020000 character special (V7) |
330 | 3000 S_IFMPC 030000 multiplexed character special (V7) | |
331 | 4000 S_IFDIR d/ 040000 directory (V7) | |
332 | 5000 S_IFNAM 050000 XENIX named special file | |
333 | with two subtypes, distinguished by st_rdev values 1, 2: | |
334 | 0001 S_INSEM s 000001 XENIX semaphore subtype of IFNAM | |
335 | 0002 S_INSHD m 000002 XENIX shared data subtype of IFNAM | |
336 | 6000 S_IFBLK b 060000 block special (V7) | |
337 | 7000 S_IFMPB 070000 multiplexed block special (V7) | |
338 | 8000 S_IFREG - 100000 regular (V7) | |
339 | 9000 S_IFCMP 110000 VxFS compressed | |
340 | 9000 S_IFNWK n 110000 network special (HP-UX) | |
341 | a000 S_IFLNK l@ 120000 symbolic link (BSD) | |
342 | b000 S_IFSHAD 130000 Solaris shadow inode for ACL (not seen by userspace) | |
343 | c000 S_IFSOCK s= 140000 socket (BSD; also "S_IFSOC" on VxFS) | |
344 | d000 S_IFDOOR D> 150000 Solaris door | |
345 | e000 S_IFWHT w% 160000 BSD whiteout (not used for inode) | |
346 | ||
347 | 0200 S_ISVTX 001000 `sticky bit': save swapped text even after use (V7) | |
348 | reserved (SVID-v2) | |
349 | On non-directories: don't cache this file (SunOS) | |
350 | On directories: restricted deletion flag (SVID-v4.2) | |
c7400a2c | 351 | 0400 S_ISGID 002000 set-group-ID on execution (V7) |
e75a4542 | 352 | for directories: use BSD semantics for propagation of GID |
da2d9dad MK |
353 | 0400 S_ENFMT 002000 SysV file locking enforcement (shared with S_ISGID) |
354 | 0800 S_ISUID 004000 set-user-ID on execution (V7) | |
fea681da MK |
355 | 0800 S_CDF 004000 directory is a context dependent file (HP-UX) |
356 | .TE | |
357 | ||
358 | A sticky command appeared in Version 32V AT&T UNIX. | |
2b2581ee MK |
359 | .SH NOTES |
360 | .SS Linux Notes | |
361 | Since kernel 2.5.48, the | |
362 | .I stat | |
363 | structure supports nanosecond resolution for the three | |
364 | file timestamp fields. | |
365 | Glibc exposes the nanosecond component of each field using names either | |
366 | of the form | |
367 | .IR st_atim.tv_nsec , | |
368 | if the _BSD_SOURCE or _SVID_SOURCE feature test macro is defined, | |
369 | or of the form | |
370 | .IR st_atimensec , | |
371 | if neither of these macros is defined. | |
372 | On file systems that do not support sub-second timestamps, | |
373 | these nanosecond fields are returned with the value 0. | |
374 | ||
375 | For most files under the | |
376 | .I /proc | |
377 | directory, | |
378 | .BR stat () | |
379 | does not return the file size in the | |
380 | .I st_size | |
381 | field; instead the field is returned with the value 0. | |
bc7ff20e MK |
382 | .SH EXAMPLE |
383 | The following program calls | |
384 | .BR stat (2) | |
385 | and displays selected fields in the returned | |
386 | .I stat | |
387 | structure. | |
388 | .nf | |
389 | ||
390 | #include <sys/types.h> | |
391 | #include <sys/stat.h> | |
392 | #include <time.h> | |
393 | #include <stdio.h> | |
394 | #include <stdlib.h> | |
395 | ||
396 | int | |
397 | main(int argc, char *argv[]) | |
398 | { | |
399 | struct stat sb; | |
400 | ||
401 | if (argc != 2) { | |
402 | fprintf(stderr, "Usage: %s <pathname>\\n", argv[0]); | |
403 | exit(EXIT_FAILURE); | |
404 | } | |
405 | ||
406 | if (stat(argv[1], &sb) == -1) { | |
407 | perror("stat"); | |
408 | exit(EXIT_SUCCESS); | |
409 | } | |
410 | ||
411 | printf("File type: "); | |
412 | switch (sb.st_mode & S_IFMT) { | |
413 | case S_IFBLK: printf("block device\\n"); break; | |
414 | case S_IFCHR: printf("character device\\n"); break; | |
415 | case S_IFDIR: printf("directory\\n"); break; | |
416 | case S_IFIFO: printf("FIFO/pipe\\n"); break; | |
417 | case S_IFLNK: printf("symlink\\n"); break; | |
418 | case S_IFREG: printf("regular file\\n"); break; | |
419 | case S_IFSOCK: printf("socket\\n"); break; | |
420 | default: printf("unknown?\\n"); break; | |
421 | } | |
422 | ||
423 | printf("I-node number: %ld\\n", (long) sb.st_ino); | |
424 | ||
425 | printf("Mode: %lo (octal)\\n", | |
426 | (unsigned long) sb.st_mode); | |
427 | ||
428 | printf("Link count: %ld\\n", (long) sb.st_nlink); | |
429 | printf("Ownership: UID=%ld GID=%ld\\n", | |
430 | (long) sb.st_uid, (long) sb.st_gid); | |
431 | ||
432 | printf("Preferred I/O block size: %ld bytes\\n", | |
433 | (long) sb.st_blksize); | |
434 | printf("File size: %lld bytes\\n", | |
435 | (long long) sb.st_size); | |
436 | printf("Blocks allocated: %lld\\n", | |
437 | (long long) sb.st_blocks); | |
438 | ||
439 | printf("Last i-node change: %s", ctime(&sb.st_ctime)); | |
440 | printf("Last file access: %s", ctime(&sb.st_atime)); | |
441 | printf("Last file modification: %s", ctime(&sb.st_mtime)); | |
442 | ||
443 | exit(EXIT_SUCCESS); | |
444 | } | |
445 | .fi | |
fea681da | 446 | .SH "SEE ALSO" |
7a5b4ffb | 447 | .BR access (2), |
fea681da MK |
448 | .BR chmod (2), |
449 | .BR chown (2), | |
956a6446 | 450 | .BR fstatat (2), |
fea681da MK |
451 | .BR readlink (2), |
452 | .BR utime (2), | |
453 | .BR capabilities (7) |