sha1_file: fast-path null sha1 as a missing object
[git/git.git] / Documentation / git-update-index.txt
1 git-update-index(1)
2 ===================
3
4 NAME
5 ----
6 git-update-index - Register file contents in the working tree to the index
7
8
9 SYNOPSIS
10 --------
11 [verse]
12 'git update-index'
13 [--add] [--remove | --force-remove] [--replace]
14 [--refresh] [-q] [--unmerged] [--ignore-missing]
15 [(--cacheinfo <mode>,<object>,<file>)...]
16 [--chmod=(+|-)x]
17 [--[no-]assume-unchanged]
18 [--[no-]skip-worktree]
19 [--ignore-submodules]
20 [--[no-]split-index]
21 [--[no-|test-|force-]untracked-cache]
22 [--really-refresh] [--unresolve] [--again | -g]
23 [--info-only] [--index-info]
24 [-z] [--stdin] [--index-version <n>]
25 [--verbose]
26 [--] [<file>...]
27
28 DESCRIPTION
29 -----------
30 Modifies the index or directory cache. Each file mentioned is updated
31 into the index and any 'unmerged' or 'needs updating' state is
32 cleared.
33
34 See also linkgit:git-add[1] for a more user-friendly way to do some of
35 the most common operations on the index.
36
37 The way 'git update-index' handles files it is told about can be modified
38 using the various options:
39
40 OPTIONS
41 -------
42 --add::
43 If a specified file isn't in the index already then it's
44 added.
45 Default behaviour is to ignore new files.
46
47 --remove::
48 If a specified file is in the index but is missing then it's
49 removed.
50 Default behavior is to ignore removed file.
51
52 --refresh::
53 Looks at the current index and checks to see if merges or
54 updates are needed by checking stat() information.
55
56 -q::
57 Quiet. If --refresh finds that the index needs an update, the
58 default behavior is to error out. This option makes
59 'git update-index' continue anyway.
60
61 --ignore-submodules::
62 Do not try to update submodules. This option is only respected
63 when passed before --refresh.
64
65 --unmerged::
66 If --refresh finds unmerged changes in the index, the default
67 behavior is to error out. This option makes 'git update-index'
68 continue anyway.
69
70 --ignore-missing::
71 Ignores missing files during a --refresh
72
73 --cacheinfo <mode>,<object>,<path>::
74 --cacheinfo <mode> <object> <path>::
75 Directly insert the specified info into the index. For
76 backward compatibility, you can also give these three
77 arguments as three separate parameters, but new users are
78 encouraged to use a single-parameter form.
79
80 --index-info::
81 Read index information from stdin.
82
83 --chmod=(+|-)x::
84 Set the execute permissions on the updated files.
85
86 --[no-]assume-unchanged::
87 When this flag is specified, the object names recorded
88 for the paths are not updated. Instead, this option
89 sets/unsets the "assume unchanged" bit for the
90 paths. When the "assume unchanged" bit is on, the user
91 promises not to change the file and allows Git to assume
92 that the working tree file matches what is recorded in
93 the index. If you want to change the working tree file,
94 you need to unset the bit to tell Git. This is
95 sometimes helpful when working with a big project on a
96 filesystem that has very slow lstat(2) system call
97 (e.g. cifs).
98 +
99 Git will fail (gracefully) in case it needs to modify this file
100 in the index e.g. when merging in a commit;
101 thus, in case the assumed-untracked file is changed upstream,
102 you will need to handle the situation manually.
103
104 --really-refresh::
105 Like `--refresh`, but checks stat information unconditionally,
106 without regard to the "assume unchanged" setting.
107
108 --[no-]skip-worktree::
109 When one of these flags is specified, the object name recorded
110 for the paths are not updated. Instead, these options
111 set and unset the "skip-worktree" bit for the paths. See
112 section "Skip-worktree bit" below for more information.
113
114 -g::
115 --again::
116 Runs 'git update-index' itself on the paths whose index
117 entries are different from those from the `HEAD` commit.
118
119 --unresolve::
120 Restores the 'unmerged' or 'needs updating' state of a
121 file during a merge if it was cleared by accident.
122
123 --info-only::
124 Do not create objects in the object database for all
125 <file> arguments that follow this flag; just insert
126 their object IDs into the index.
127
128 --force-remove::
129 Remove the file from the index even when the working directory
130 still has such a file. (Implies --remove.)
131
132 --replace::
133 By default, when a file `path` exists in the index,
134 'git update-index' refuses an attempt to add `path/file`.
135 Similarly if a file `path/file` exists, a file `path`
136 cannot be added. With --replace flag, existing entries
137 that conflict with the entry being added are
138 automatically removed with warning messages.
139
140 --stdin::
141 Instead of taking list of paths from the command line,
142 read list of paths from the standard input. Paths are
143 separated by LF (i.e. one path per line) by default.
144
145 --verbose::
146 Report what is being added and removed from index.
147
148 --index-version <n>::
149 Write the resulting index out in the named on-disk format version.
150 Supported versions are 2, 3 and 4. The current default version is 2
151 or 3, depending on whether extra features are used, such as
152 `git add -N`.
153 +
154 Version 4 performs a simple pathname compression that reduces index
155 size by 30%-50% on large repositories, which results in faster load
156 time. Version 4 is relatively young (first released in 1.8.0 in
157 October 2012). Other Git implementations such as JGit and libgit2
158 may not support it yet.
159
160 -z::
161 Only meaningful with `--stdin` or `--index-info`; paths are
162 separated with NUL character instead of LF.
163
164 --split-index::
165 --no-split-index::
166 Enable or disable split index mode. If split-index mode is
167 already enabled and `--split-index` is given again, all
168 changes in $GIT_DIR/index are pushed back to the shared index
169 file.
170 +
171 These options take effect whatever the value of the `core.splitIndex`
172 configuration variable (see linkgit:git-config[1]). But a warning is
173 emitted when the change goes against the configured value, as the
174 configured value will take effect next time the index is read and this
175 will remove the intended effect of the option.
176
177 --untracked-cache::
178 --no-untracked-cache::
179 Enable or disable untracked cache feature. Please use
180 `--test-untracked-cache` before enabling it.
181 +
182 These options take effect whatever the value of the `core.untrackedCache`
183 configuration variable (see linkgit:git-config[1]). But a warning is
184 emitted when the change goes against the configured value, as the
185 configured value will take effect next time the index is read and this
186 will remove the intended effect of the option.
187
188 --test-untracked-cache::
189 Only perform tests on the working directory to make sure
190 untracked cache can be used. You have to manually enable
191 untracked cache using `--untracked-cache` or
192 `--force-untracked-cache` or the `core.untrackedCache`
193 configuration variable afterwards if you really want to use
194 it. If a test fails the exit code is 1 and a message
195 explains what is not working as needed, otherwise the exit
196 code is 0 and OK is printed.
197
198 --force-untracked-cache::
199 Same as `--untracked-cache`. Provided for backwards
200 compatibility with older versions of Git where
201 `--untracked-cache` used to imply `--test-untracked-cache` but
202 this option would enable the extension unconditionally.
203
204 \--::
205 Do not interpret any more arguments as options.
206
207 <file>::
208 Files to act on.
209 Note that files beginning with '.' are discarded. This includes
210 `./file` and `dir/./file`. If you don't want this, then use
211 cleaner names.
212 The same applies to directories ending '/' and paths with '//'
213
214 Using --refresh
215 ---------------
216 `--refresh` does not calculate a new sha1 file or bring the index
217 up-to-date for mode/content changes. But what it *does* do is to
218 "re-match" the stat information of a file with the index, so that you
219 can refresh the index for a file that hasn't been changed but where
220 the stat entry is out of date.
221
222 For example, you'd want to do this after doing a 'git read-tree', to link
223 up the stat index details with the proper files.
224
225 Using --cacheinfo or --info-only
226 --------------------------------
227 `--cacheinfo` is used to register a file that is not in the
228 current working directory. This is useful for minimum-checkout
229 merging.
230
231 To pretend you have a file with mode and sha1 at path, say:
232
233 ----------------
234 $ git update-index --cacheinfo <mode>,<sha1>,<path>
235 ----------------
236
237 `--info-only` is used to register files without placing them in the object
238 database. This is useful for status-only repositories.
239
240 Both `--cacheinfo` and `--info-only` behave similarly: the index is updated
241 but the object database isn't. `--cacheinfo` is useful when the object is
242 in the database but the file isn't available locally. `--info-only` is
243 useful when the file is available, but you do not wish to update the
244 object database.
245
246
247 Using --index-info
248 ------------------
249
250 `--index-info` is a more powerful mechanism that lets you feed
251 multiple entry definitions from the standard input, and designed
252 specifically for scripts. It can take inputs of three formats:
253
254 . mode SP sha1 TAB path
255 +
256 The first format is what "git-apply --index-info"
257 reports, and used to reconstruct a partial tree
258 that is used for phony merge base tree when falling
259 back on 3-way merge.
260
261 . mode SP type SP sha1 TAB path
262 +
263 The second format is to stuff 'git ls-tree' output
264 into the index file.
265
266 . mode SP sha1 SP stage TAB path
267 +
268 This format is to put higher order stages into the
269 index file and matches 'git ls-files --stage' output.
270
271 To place a higher stage entry to the index, the path should
272 first be removed by feeding a mode=0 entry for the path, and
273 then feeding necessary input lines in the third format.
274
275 For example, starting with this index:
276
277 ------------
278 $ git ls-files -s
279 100644 8a1218a1024a212bb3db30becd860315f9f3ac52 0 frotz
280 ------------
281
282 you can feed the following input to `--index-info`:
283
284 ------------
285 $ git update-index --index-info
286 0 0000000000000000000000000000000000000000 frotz
287 100644 8a1218a1024a212bb3db30becd860315f9f3ac52 1 frotz
288 100755 8a1218a1024a212bb3db30becd860315f9f3ac52 2 frotz
289 ------------
290
291 The first line of the input feeds 0 as the mode to remove the
292 path; the SHA-1 does not matter as long as it is well formatted.
293 Then the second and third line feeds stage 1 and stage 2 entries
294 for that path. After the above, we would end up with this:
295
296 ------------
297 $ git ls-files -s
298 100644 8a1218a1024a212bb3db30becd860315f9f3ac52 1 frotz
299 100755 8a1218a1024a212bb3db30becd860315f9f3ac52 2 frotz
300 ------------
301
302
303 Using ``assume unchanged'' bit
304 ------------------------------
305
306 Many operations in Git depend on your filesystem to have an
307 efficient `lstat(2)` implementation, so that `st_mtime`
308 information for working tree files can be cheaply checked to see
309 if the file contents have changed from the version recorded in
310 the index file. Unfortunately, some filesystems have
311 inefficient `lstat(2)`. If your filesystem is one of them, you
312 can set "assume unchanged" bit to paths you have not changed to
313 cause Git not to do this check. Note that setting this bit on a
314 path does not mean Git will check the contents of the file to
315 see if it has changed -- it makes Git to omit any checking and
316 assume it has *not* changed. When you make changes to working
317 tree files, you have to explicitly tell Git about it by dropping
318 "assume unchanged" bit, either before or after you modify them.
319
320 In order to set "assume unchanged" bit, use `--assume-unchanged`
321 option. To unset, use `--no-assume-unchanged`. To see which files
322 have the "assume unchanged" bit set, use `git ls-files -v`
323 (see linkgit:git-ls-files[1]).
324
325 The command looks at `core.ignorestat` configuration variable. When
326 this is true, paths updated with `git update-index paths...` and
327 paths updated with other Git commands that update both index and
328 working tree (e.g. 'git apply --index', 'git checkout-index -u',
329 and 'git read-tree -u') are automatically marked as "assume
330 unchanged". Note that "assume unchanged" bit is *not* set if
331 `git update-index --refresh` finds the working tree file matches
332 the index (use `git update-index --really-refresh` if you want
333 to mark them as "assume unchanged").
334
335
336 Examples
337 --------
338 To update and refresh only the files already checked out:
339
340 ----------------
341 $ git checkout-index -n -f -a && git update-index --ignore-missing --refresh
342 ----------------
343
344 On an inefficient filesystem with `core.ignorestat` set::
345 +
346 ------------
347 $ git update-index --really-refresh <1>
348 $ git update-index --no-assume-unchanged foo.c <2>
349 $ git diff --name-only <3>
350 $ edit foo.c
351 $ git diff --name-only <4>
352 M foo.c
353 $ git update-index foo.c <5>
354 $ git diff --name-only <6>
355 $ edit foo.c
356 $ git diff --name-only <7>
357 $ git update-index --no-assume-unchanged foo.c <8>
358 $ git diff --name-only <9>
359 M foo.c
360 ------------
361 +
362 <1> forces lstat(2) to set "assume unchanged" bits for paths that match index.
363 <2> mark the path to be edited.
364 <3> this does lstat(2) and finds index matches the path.
365 <4> this does lstat(2) and finds index does *not* match the path.
366 <5> registering the new version to index sets "assume unchanged" bit.
367 <6> and it is assumed unchanged.
368 <7> even after you edit it.
369 <8> you can tell about the change after the fact.
370 <9> now it checks with lstat(2) and finds it has been changed.
371
372
373 Skip-worktree bit
374 -----------------
375
376 Skip-worktree bit can be defined in one (long) sentence: When reading
377 an entry, if it is marked as skip-worktree, then Git pretends its
378 working directory version is up to date and read the index version
379 instead.
380
381 To elaborate, "reading" means checking for file existence, reading
382 file attributes or file content. The working directory version may be
383 present or absent. If present, its content may match against the index
384 version or not. Writing is not affected by this bit, content safety
385 is still first priority. Note that Git _can_ update working directory
386 file, that is marked skip-worktree, if it is safe to do so (i.e.
387 working directory version matches index version)
388
389 Although this bit looks similar to assume-unchanged bit, its goal is
390 different from assume-unchanged bit's. Skip-worktree also takes
391 precedence over assume-unchanged bit when both are set.
392
393 Split index
394 -----------
395
396 This mode is designed for repositories with very large indexes, and
397 aims at reducing the time it takes to repeatedly write these indexes.
398
399 In this mode, the index is split into two files, $GIT_DIR/index and
400 $GIT_DIR/sharedindex.<SHA-1>. Changes are accumulated in
401 $GIT_DIR/index, the split index, while the shared index file contains
402 all index entries and stays unchanged.
403
404 All changes in the split index are pushed back to the shared index
405 file when the number of entries in the split index reaches a level
406 specified by the splitIndex.maxPercentChange config variable (see
407 linkgit:git-config[1]).
408
409 Each time a new shared index file is created, the old shared index
410 files are deleted if their modification time is older than what is
411 specified by the splitIndex.sharedIndexExpire config variable (see
412 linkgit:git-config[1]).
413
414 To avoid deleting a shared index file that is still used, its
415 modification time is updated to the current time everytime a new split
416 index based on the shared index file is either created or read from.
417
418 Untracked cache
419 ---------------
420
421 This cache is meant to speed up commands that involve determining
422 untracked files such as `git status`.
423
424 This feature works by recording the mtime of the working tree
425 directories and then omitting reading directories and stat calls
426 against files in those directories whose mtime hasn't changed. For
427 this to work the underlying operating system and file system must
428 change the `st_mtime` field of directories if files in the directory
429 are added, modified or deleted.
430
431 You can test whether the filesystem supports that with the
432 `--test-untracked-cache` option. The `--untracked-cache` option used
433 to implicitly perform that test in older versions of Git, but that's
434 no longer the case.
435
436 If you want to enable (or disable) this feature, it is easier to use
437 the `core.untrackedCache` configuration variable (see
438 linkgit:git-config[1]) than using the `--untracked-cache` option to
439 `git update-index` in each repository, especially if you want to do so
440 across all repositories you use, because you can set the configuration
441 variable to `true` (or `false`) in your `$HOME/.gitconfig` just once
442 and have it affect all repositories you touch.
443
444 When the `core.untrackedCache` configuration variable is changed, the
445 untracked cache is added to or removed from the index the next time a
446 command reads the index; while when `--[no-|force-]untracked-cache`
447 are used, the untracked cache is immediately added to or removed from
448 the index.
449
450 Configuration
451 -------------
452
453 The command honors `core.filemode` configuration variable. If
454 your repository is on a filesystem whose executable bits are
455 unreliable, this should be set to 'false' (see linkgit:git-config[1]).
456 This causes the command to ignore differences in file modes recorded
457 in the index and the file mode on the filesystem if they differ only on
458 executable bit. On such an unfortunate filesystem, you may
459 need to use 'git update-index --chmod='.
460
461 Quite similarly, if `core.symlinks` configuration variable is set
462 to 'false' (see linkgit:git-config[1]), symbolic links are checked out
463 as plain files, and this command does not modify a recorded file mode
464 from symbolic link to regular file.
465
466 The command looks at `core.ignorestat` configuration variable. See
467 'Using "assume unchanged" bit' section above.
468
469 The command also looks at `core.trustctime` configuration variable.
470 It can be useful when the inode change time is regularly modified by
471 something outside Git (file system crawlers and backup systems use
472 ctime for marking files processed) (see linkgit:git-config[1]).
473
474 The untracked cache extension can be enabled by the
475 `core.untrackedCache` configuration variable (see
476 linkgit:git-config[1]).
477
478 SEE ALSO
479 --------
480 linkgit:git-config[1],
481 linkgit:git-add[1],
482 linkgit:git-ls-files[1]
483
484 GIT
485 ---
486 Part of the linkgit:git[1] suite