summaryrefslogtreecommitdiff
path: root/Doc/library/stat.rst
blob: 24769f6893217c7d94b3bb64eb3b786e94ea70e4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
:mod:`stat` --- Interpreting :func:`~os.stat` results
=====================================================

.. module:: stat
   :synopsis: Utilities for interpreting the results of os.stat(),
              os.lstat() and os.fstat().
.. sectionauthor:: Skip Montanaro <skip@automatrix.com>

**Source code:** :source:`Modules/_stat.c`
                 :source:`Lib/stat.py`

--------------

The :mod:`stat` module defines constants and functions for interpreting the
results of :func:`os.stat`, :func:`os.fstat` and :func:`os.lstat` (if they
exist).  For complete details about the :c:func:`stat`, :c:func:`fstat` and
:c:func:`lstat` calls, consult the documentation for your system.

.. versionchanged:: 3.4
   The stat module is backed by a C implementation.

The :mod:`stat` module defines the following functions to test for specific file
types:


.. function:: S_ISDIR(mode)

   Return non-zero if the mode is from a directory.


.. function:: S_ISCHR(mode)

   Return non-zero if the mode is from a character special device file.


.. function:: S_ISBLK(mode)

   Return non-zero if the mode is from a block special device file.


.. function:: S_ISREG(mode)

   Return non-zero if the mode is from a regular file.


.. function:: S_ISFIFO(mode)

   Return non-zero if the mode is from a FIFO (named pipe).


.. function:: S_ISLNK(mode)

   Return non-zero if the mode is from a symbolic link.


.. function:: S_ISSOCK(mode)

   Return non-zero if the mode is from a socket.

.. function:: S_ISDOOR(mode)

   Return non-zero if the mode is from a door.

   .. versionadded:: 3.4

.. function:: S_ISPORT(mode)

   Return non-zero if the mode is from an event port.

   .. versionadded:: 3.4

.. function:: S_ISWHT(mode)

   Return non-zero if the mode is from a whiteout.

   .. versionadded:: 3.4

Two additional functions are defined for more general manipulation of the file's
mode:


.. function:: S_IMODE(mode)

   Return the portion of the file's mode that can be set by :func:`os.chmod`\
   ---that is, the file's permission bits, plus the sticky bit, set-group-id, and
   set-user-id bits (on systems that support them).


.. function:: S_IFMT(mode)

   Return the portion of the file's mode that describes the file type (used by the
   :func:`S_IS\*` functions above).

Normally, you would use the :func:`os.path.is\*` functions for testing the type
of a file; the functions here are useful when you are doing multiple tests of
the same file and wish to avoid the overhead of the :c:func:`stat` system call
for each test.  These are also useful when checking for information about a file
that isn't handled by :mod:`os.path`, like the tests for block and character
devices.

Example::

   import os, sys
   from stat import *

   def walktree(top, callback):
       '''recursively descend the directory tree rooted at top,
          calling the callback function for each regular file'''

       for f in os.listdir(top):
           pathname = os.path.join(top, f)
           mode = os.stat(pathname).st_mode
           if S_ISDIR(mode):
               # It's a directory, recurse into it
               walktree(pathname, callback)
           elif S_ISREG(mode):
               # It's a file, call the callback function
               callback(pathname)
           else:
               # Unknown file type, print a message
               print('Skipping %s' % pathname)

   def visitfile(file):
       print('visiting', file)

   if __name__ == '__main__':
       walktree(sys.argv[1], visitfile)

An additional utility function is provided to covert a file's mode in a human
readable string:

.. function:: filemode(mode)

   Convert a file's mode to a string of the form '-rwxrwxrwx'.

   .. versionadded:: 3.3

   .. versionchanged:: 3.4
      The function supports :data:`S_IFDOOR`, :data:`S_IFPORT` and
      :data:`S_IFWHT`.


All the variables below are simply symbolic indexes into the 10-tuple returned
by :func:`os.stat`, :func:`os.fstat` or :func:`os.lstat`.


.. data:: ST_MODE

   Inode protection mode.


.. data:: ST_INO

   Inode number.


.. data:: ST_DEV

   Device inode resides on.


.. data:: ST_NLINK

   Number of links to the inode.


.. data:: ST_UID

   User id of the owner.


.. data:: ST_GID

   Group id of the owner.


.. data:: ST_SIZE

   Size in bytes of a plain file; amount of data waiting on some special files.


.. data:: ST_ATIME

   Time of last access.


.. data:: ST_MTIME

   Time of last modification.


.. data:: ST_CTIME

   The "ctime" as reported by the operating system.  On some systems (like Unix) is
   the time of the last metadata change, and, on others (like Windows), is the
   creation time (see platform documentation for details).

The interpretation of "file size" changes according to the file type.  For plain
files this is the size of the file in bytes.  For FIFOs and sockets under most
flavors of Unix (including Linux in particular), the "size" is the number of
bytes waiting to be read at the time of the call to :func:`os.stat`,
:func:`os.fstat`, or :func:`os.lstat`; this can sometimes be useful, especially
for polling one of these special files after a non-blocking open.  The meaning
of the size field for other character and block devices varies more, depending
on the implementation of the underlying system call.

The variables below define the flags used in the :data:`ST_MODE` field.

Use of the functions above is more portable than use of the first set of flags:

.. data:: S_IFSOCK

   Socket.

.. data:: S_IFLNK

   Symbolic link.

.. data:: S_IFREG

   Regular file.

.. data:: S_IFBLK

   Block device.

.. data:: S_IFDIR

   Directory.

.. data:: S_IFCHR

   Character device.

.. data:: S_IFIFO

   FIFO.

.. data:: S_IFDOOR

   Door.

   .. versionadded:: 3.4

.. data:: S_IFPORT

   Event port.

   .. versionadded:: 3.4

.. data:: S_IFWHT

   Whiteout.

   .. versionadded:: 3.4

.. note::

   :data:`S_IFDOOR`, :data:`S_IFPORT` or :data:`S_IFWHT` are defined as
   0 when the platform does not have support for the file types.

The following flags can also be used in the *mode* argument of :func:`os.chmod`:

.. data:: S_ISUID

   Set UID bit.

.. data:: S_ISGID

   Set-group-ID bit.  This bit has several special uses.  For a directory
   it indicates that BSD semantics is to be used for that directory:
   files created there inherit their group ID from the directory, not
   from the effective group ID of the creating process, and directories
   created there will also get the :data:`S_ISGID` bit set.  For a
   file that does not have the group execution bit (:data:`S_IXGRP`)
   set, the set-group-ID bit indicates mandatory file/record locking
   (see also :data:`S_ENFMT`).

.. data:: S_ISVTX

   Sticky bit.  When this bit is set on a directory it means that a file
   in that directory can be renamed or deleted only by the owner of the
   file, by the owner of the directory, or by a privileged process.

.. data:: S_IRWXU

   Mask for file owner permissions.

.. data:: S_IRUSR

   Owner has read permission.

.. data:: S_IWUSR

   Owner has write permission.

.. data:: S_IXUSR

   Owner has execute permission.

.. data:: S_IRWXG

   Mask for group permissions.

.. data:: S_IRGRP

   Group has read permission.

.. data:: S_IWGRP

   Group has write permission.

.. data:: S_IXGRP

   Group has execute permission.

.. data:: S_IRWXO

   Mask for permissions for others (not in group).

.. data:: S_IROTH

   Others have read permission.

.. data:: S_IWOTH

   Others have write permission.

.. data:: S_IXOTH

   Others have execute permission.

.. data:: S_ENFMT

   System V file locking enforcement.  This flag is shared with :data:`S_ISGID`:
   file/record locking is enforced on files that do not have the group
   execution bit (:data:`S_IXGRP`) set.

.. data:: S_IREAD

   Unix V7 synonym for :data:`S_IRUSR`.

.. data:: S_IWRITE

   Unix V7 synonym for :data:`S_IWUSR`.

.. data:: S_IEXEC

   Unix V7 synonym for :data:`S_IXUSR`.

The following flags can be used in the *flags* argument of :func:`os.chflags`:

.. data:: UF_NODUMP

   Do not dump the file.

.. data:: UF_IMMUTABLE

   The file may not be changed.

.. data:: UF_APPEND

   The file may only be appended to.

.. data:: UF_OPAQUE

   The directory is opaque when viewed through a union stack.

.. data:: UF_NOUNLINK

   The file may not be renamed or deleted.

.. data:: UF_COMPRESSED

   The file is stored compressed (Mac OS X 10.6+).

.. data:: UF_HIDDEN

   The file should not be displayed in a GUI (Mac OS X 10.5+).

.. data:: SF_ARCHIVED

   The file may be archived.

.. data:: SF_IMMUTABLE

   The file may not be changed.

.. data:: SF_APPEND

   The file may only be appended to.

.. data:: SF_NOUNLINK

   The file may not be renamed or deleted.

.. data:: SF_SNAPSHOT

   The file is a snapshot file.

See the \*BSD or Mac OS systems man page :manpage:`chflags(2)` for more information.