pack-objects: use reachability bitmap index when generating non-stdout pack
[git/git.git] / Documentation / gitattributes.txt
1 gitattributes(5)
2 ================
3
4 NAME
5 ----
6 gitattributes - defining attributes per path
7
8 SYNOPSIS
9 --------
10 $GIT_DIR/info/attributes, .gitattributes
11
12
13 DESCRIPTION
14 -----------
15
16 A `gitattributes` file is a simple text file that gives
17 `attributes` to pathnames.
18
19 Each line in `gitattributes` file is of form:
20
21 pattern attr1 attr2 ...
22
23 That is, a pattern followed by an attributes list,
24 separated by whitespaces. When the pattern matches the
25 path in question, the attributes listed on the line are given to
26 the path.
27
28 Each attribute can be in one of these states for a given path:
29
30 Set::
31
32 The path has the attribute with special value "true";
33 this is specified by listing only the name of the
34 attribute in the attribute list.
35
36 Unset::
37
38 The path has the attribute with special value "false";
39 this is specified by listing the name of the attribute
40 prefixed with a dash `-` in the attribute list.
41
42 Set to a value::
43
44 The path has the attribute with specified string value;
45 this is specified by listing the name of the attribute
46 followed by an equal sign `=` and its value in the
47 attribute list.
48
49 Unspecified::
50
51 No pattern matches the path, and nothing says if
52 the path has or does not have the attribute, the
53 attribute for the path is said to be Unspecified.
54
55 When more than one pattern matches the path, a later line
56 overrides an earlier line. This overriding is done per
57 attribute. The rules how the pattern matches paths are the
58 same as in `.gitignore` files; see linkgit:gitignore[5].
59 Unlike `.gitignore`, negative patterns are forbidden.
60
61 When deciding what attributes are assigned to a path, Git
62 consults `$GIT_DIR/info/attributes` file (which has the highest
63 precedence), `.gitattributes` file in the same directory as the
64 path in question, and its parent directories up to the toplevel of the
65 work tree (the further the directory that contains `.gitattributes`
66 is from the path in question, the lower its precedence). Finally
67 global and system-wide files are considered (they have the lowest
68 precedence).
69
70 When the `.gitattributes` file is missing from the work tree, the
71 path in the index is used as a fall-back. During checkout process,
72 `.gitattributes` in the index is used and then the file in the
73 working tree is used as a fall-back.
74
75 If you wish to affect only a single repository (i.e., to assign
76 attributes to files that are particular to
77 one user's workflow for that repository), then
78 attributes should be placed in the `$GIT_DIR/info/attributes` file.
79 Attributes which should be version-controlled and distributed to other
80 repositories (i.e., attributes of interest to all users) should go into
81 `.gitattributes` files. Attributes that should affect all repositories
82 for a single user should be placed in a file specified by the
83 `core.attributesFile` configuration option (see linkgit:git-config[1]).
84 Its default value is $XDG_CONFIG_HOME/git/attributes. If $XDG_CONFIG_HOME
85 is either not set or empty, $HOME/.config/git/attributes is used instead.
86 Attributes for all users on a system should be placed in the
87 `$(prefix)/etc/gitattributes` file.
88
89 Sometimes you would need to override an setting of an attribute
90 for a path to `Unspecified` state. This can be done by listing
91 the name of the attribute prefixed with an exclamation point `!`.
92
93
94 EFFECTS
95 -------
96
97 Certain operations by Git can be influenced by assigning
98 particular attributes to a path. Currently, the following
99 operations are attributes-aware.
100
101 Checking-out and checking-in
102 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
103
104 These attributes affect how the contents stored in the
105 repository are copied to the working tree files when commands
106 such as 'git checkout' and 'git merge' run. They also affect how
107 Git stores the contents you prepare in the working tree in the
108 repository upon 'git add' and 'git commit'.
109
110 `text`
111 ^^^^^^
112
113 This attribute enables and controls end-of-line normalization. When a
114 text file is normalized, its line endings are converted to LF in the
115 repository. To control what line ending style is used in the working
116 directory, use the `eol` attribute for a single file and the
117 `core.eol` configuration variable for all text files.
118
119 Set::
120
121 Setting the `text` attribute on a path enables end-of-line
122 normalization and marks the path as a text file. End-of-line
123 conversion takes place without guessing the content type.
124
125 Unset::
126
127 Unsetting the `text` attribute on a path tells Git not to
128 attempt any end-of-line conversion upon checkin or checkout.
129
130 Set to string value "auto"::
131
132 When `text` is set to "auto", the path is marked for automatic
133 end-of-line normalization. If Git decides that the content is
134 text, its line endings are normalized to LF on checkin.
135
136 Unspecified::
137
138 If the `text` attribute is unspecified, Git uses the
139 `core.autocrlf` configuration variable to determine if the
140 file should be converted.
141
142 Any other value causes Git to act as if `text` has been left
143 unspecified.
144
145 `eol`
146 ^^^^^
147
148 This attribute sets a specific line-ending style to be used in the
149 working directory. It enables end-of-line normalization without any
150 content checks, effectively setting the `text` attribute.
151
152 Set to string value "crlf"::
153
154 This setting forces Git to normalize line endings for this
155 file on checkin and convert them to CRLF when the file is
156 checked out.
157
158 Set to string value "lf"::
159
160 This setting forces Git to normalize line endings to LF on
161 checkin and prevents conversion to CRLF when the file is
162 checked out.
163
164 Backwards compatibility with `crlf` attribute
165 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
166
167 For backwards compatibility, the `crlf` attribute is interpreted as
168 follows:
169
170 ------------------------
171 crlf text
172 -crlf -text
173 crlf=input eol=lf
174 ------------------------
175
176 End-of-line conversion
177 ^^^^^^^^^^^^^^^^^^^^^^
178
179 While Git normally leaves file contents alone, it can be configured to
180 normalize line endings to LF in the repository and, optionally, to
181 convert them to CRLF when files are checked out.
182
183 Here is an example that will make Git normalize .txt, .vcproj and .sh
184 files, ensure that .vcproj files have CRLF and .sh files have LF in
185 the working directory, and prevent .jpg files from being normalized
186 regardless of their content.
187
188 ------------------------
189 *.txt text
190 *.vcproj eol=crlf
191 *.sh eol=lf
192 *.jpg -text
193 ------------------------
194
195 Other source code management systems normalize all text files in their
196 repositories, and there are two ways to enable similar automatic
197 normalization in Git.
198
199 If you simply want to have CRLF line endings in your working directory
200 regardless of the repository you are working with, you can set the
201 config variable "core.autocrlf" without changing any attributes.
202
203 ------------------------
204 [core]
205 autocrlf = true
206 ------------------------
207
208 This does not force normalization of all text files, but does ensure
209 that text files that you introduce to the repository have their line
210 endings normalized to LF when they are added, and that files that are
211 already normalized in the repository stay normalized.
212
213 If you want to interoperate with a source code management system that
214 enforces end-of-line normalization, or you simply want all text files
215 in your repository to be normalized, you should instead set the `text`
216 attribute to "auto" for _all_ files.
217
218 ------------------------
219 * text=auto
220 ------------------------
221
222 This ensures that all files that Git considers to be text will have
223 normalized (LF) line endings in the repository. The `core.eol`
224 configuration variable controls which line endings Git will use for
225 normalized files in your working directory; the default is to use the
226 native line ending for your platform, or CRLF if `core.autocrlf` is
227 set.
228
229 NOTE: When `text=auto` normalization is enabled in an existing
230 repository, any text files containing CRLFs should be normalized. If
231 they are not they will be normalized the next time someone tries to
232 change them, causing unfortunate misattribution. From a clean working
233 directory:
234
235 -------------------------------------------------
236 $ echo "* text=auto" >>.gitattributes
237 $ rm .git/index # Remove the index to force Git to
238 $ git reset # re-scan the working directory
239 $ git status # Show files that will be normalized
240 $ git add -u
241 $ git add .gitattributes
242 $ git commit -m "Introduce end-of-line normalization"
243 -------------------------------------------------
244
245 If any files that should not be normalized show up in 'git status',
246 unset their `text` attribute before running 'git add -u'.
247
248 ------------------------
249 manual.pdf -text
250 ------------------------
251
252 Conversely, text files that Git does not detect can have normalization
253 enabled manually.
254
255 ------------------------
256 weirdchars.txt text
257 ------------------------
258
259 If `core.safecrlf` is set to "true" or "warn", Git verifies if
260 the conversion is reversible for the current setting of
261 `core.autocrlf`. For "true", Git rejects irreversible
262 conversions; for "warn", Git only prints a warning but accepts
263 an irreversible conversion. The safety triggers to prevent such
264 a conversion done to the files in the work tree, but there are a
265 few exceptions. Even though...
266
267 - 'git add' itself does not touch the files in the work tree, the
268 next checkout would, so the safety triggers;
269
270 - 'git apply' to update a text file with a patch does touch the files
271 in the work tree, but the operation is about text files and CRLF
272 conversion is about fixing the line ending inconsistencies, so the
273 safety does not trigger;
274
275 - 'git diff' itself does not touch the files in the work tree, it is
276 often run to inspect the changes you intend to next 'git add'. To
277 catch potential problems early, safety triggers.
278
279
280 `ident`
281 ^^^^^^^
282
283 When the attribute `ident` is set for a path, Git replaces
284 `$Id$` in the blob object with `$Id:`, followed by the
285 40-character hexadecimal blob object name, followed by a dollar
286 sign `$` upon checkout. Any byte sequence that begins with
287 `$Id:` and ends with `$` in the worktree file is replaced
288 with `$Id$` upon check-in.
289
290
291 `filter`
292 ^^^^^^^^
293
294 A `filter` attribute can be set to a string value that names a
295 filter driver specified in the configuration.
296
297 A filter driver consists of a `clean` command and a `smudge`
298 command, either of which can be left unspecified. Upon
299 checkout, when the `smudge` command is specified, the command is
300 fed the blob object from its standard input, and its standard
301 output is used to update the worktree file. Similarly, the
302 `clean` command is used to convert the contents of worktree file
303 upon checkin.
304
305 One use of the content filtering is to massage the content into a shape
306 that is more convenient for the platform, filesystem, and the user to use.
307 For this mode of operation, the key phrase here is "more convenient" and
308 not "turning something unusable into usable". In other words, the intent
309 is that if someone unsets the filter driver definition, or does not have
310 the appropriate filter program, the project should still be usable.
311
312 Another use of the content filtering is to store the content that cannot
313 be directly used in the repository (e.g. a UUID that refers to the true
314 content stored outside Git, or an encrypted content) and turn it into a
315 usable form upon checkout (e.g. download the external content, or decrypt
316 the encrypted content).
317
318 These two filters behave differently, and by default, a filter is taken as
319 the former, massaging the contents into more convenient shape. A missing
320 filter driver definition in the config, or a filter driver that exits with
321 a non-zero status, is not an error but makes the filter a no-op passthru.
322
323 You can declare that a filter turns a content that by itself is unusable
324 into a usable content by setting the filter.<driver>.required configuration
325 variable to `true`.
326
327 For example, in .gitattributes, you would assign the `filter`
328 attribute for paths.
329
330 ------------------------
331 *.c filter=indent
332 ------------------------
333
334 Then you would define a "filter.indent.clean" and "filter.indent.smudge"
335 configuration in your .git/config to specify a pair of commands to
336 modify the contents of C programs when the source files are checked
337 in ("clean" is run) and checked out (no change is made because the
338 command is "cat").
339
340 ------------------------
341 [filter "indent"]
342 clean = indent
343 smudge = cat
344 ------------------------
345
346 For best results, `clean` should not alter its output further if it is
347 run twice ("clean->clean" should be equivalent to "clean"), and
348 multiple `smudge` commands should not alter `clean`'s output
349 ("smudge->smudge->clean" should be equivalent to "clean"). See the
350 section on merging below.
351
352 The "indent" filter is well-behaved in this regard: it will not modify
353 input that is already correctly indented. In this case, the lack of a
354 smudge filter means that the clean filter _must_ accept its own output
355 without modifying it.
356
357 If a filter _must_ succeed in order to make the stored contents usable,
358 you can declare that the filter is `required`, in the configuration:
359
360 ------------------------
361 [filter "crypt"]
362 clean = openssl enc ...
363 smudge = openssl enc -d ...
364 required
365 ------------------------
366
367 Sequence "%f" on the filter command line is replaced with the name of
368 the file the filter is working on. A filter might use this in keyword
369 substitution. For example:
370
371 ------------------------
372 [filter "p4"]
373 clean = git-p4-filter --clean %f
374 smudge = git-p4-filter --smudge %f
375 ------------------------
376
377
378 Interaction between checkin/checkout attributes
379 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
380
381 In the check-in codepath, the worktree file is first converted
382 with `filter` driver (if specified and corresponding driver
383 defined), then the result is processed with `ident` (if
384 specified), and then finally with `text` (again, if specified
385 and applicable).
386
387 In the check-out codepath, the blob content is first converted
388 with `text`, and then `ident` and fed to `filter`.
389
390
391 Merging branches with differing checkin/checkout attributes
392 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
393
394 If you have added attributes to a file that cause the canonical
395 repository format for that file to change, such as adding a
396 clean/smudge filter or text/eol/ident attributes, merging anything
397 where the attribute is not in place would normally cause merge
398 conflicts.
399
400 To prevent these unnecessary merge conflicts, Git can be told to run a
401 virtual check-out and check-in of all three stages of a file when
402 resolving a three-way merge by setting the `merge.renormalize`
403 configuration variable. This prevents changes caused by check-in
404 conversion from causing spurious merge conflicts when a converted file
405 is merged with an unconverted file.
406
407 As long as a "smudge->clean" results in the same output as a "clean"
408 even on files that are already smudged, this strategy will
409 automatically resolve all filter-related conflicts. Filters that do
410 not act in this way may cause additional merge conflicts that must be
411 resolved manually.
412
413
414 Generating diff text
415 ~~~~~~~~~~~~~~~~~~~~
416
417 `diff`
418 ^^^^^^
419
420 The attribute `diff` affects how Git generates diffs for particular
421 files. It can tell Git whether to generate a textual patch for the path
422 or to treat the path as a binary file. It can also affect what line is
423 shown on the hunk header `@@ -k,l +n,m @@` line, tell Git to use an
424 external command to generate the diff, or ask Git to convert binary
425 files to a text format before generating the diff.
426
427 Set::
428
429 A path to which the `diff` attribute is set is treated
430 as text, even when they contain byte values that
431 normally never appear in text files, such as NUL.
432
433 Unset::
434
435 A path to which the `diff` attribute is unset will
436 generate `Binary files differ` (or a binary patch, if
437 binary patches are enabled).
438
439 Unspecified::
440
441 A path to which the `diff` attribute is unspecified
442 first gets its contents inspected, and if it looks like
443 text and is smaller than core.bigFileThreshold, it is treated
444 as text. Otherwise it would generate `Binary files differ`.
445
446 String::
447
448 Diff is shown using the specified diff driver. Each driver may
449 specify one or more options, as described in the following
450 section. The options for the diff driver "foo" are defined
451 by the configuration variables in the "diff.foo" section of the
452 Git config file.
453
454
455 Defining an external diff driver
456 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
457
458 The definition of a diff driver is done in `gitconfig`, not
459 `gitattributes` file, so strictly speaking this manual page is a
460 wrong place to talk about it. However...
461
462 To define an external diff driver `jcdiff`, add a section to your
463 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
464
465 ----------------------------------------------------------------
466 [diff "jcdiff"]
467 command = j-c-diff
468 ----------------------------------------------------------------
469
470 When Git needs to show you a diff for the path with `diff`
471 attribute set to `jcdiff`, it calls the command you specified
472 with the above configuration, i.e. `j-c-diff`, with 7
473 parameters, just like `GIT_EXTERNAL_DIFF` program is called.
474 See linkgit:git[1] for details.
475
476
477 Defining a custom hunk-header
478 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
479
480 Each group of changes (called a "hunk") in the textual diff output
481 is prefixed with a line of the form:
482
483 @@ -k,l +n,m @@ TEXT
484
485 This is called a 'hunk header'. The "TEXT" portion is by default a line
486 that begins with an alphabet, an underscore or a dollar sign; this
487 matches what GNU 'diff -p' output uses. This default selection however
488 is not suited for some contents, and you can use a customized pattern
489 to make a selection.
490
491 First, in .gitattributes, you would assign the `diff` attribute
492 for paths.
493
494 ------------------------
495 *.tex diff=tex
496 ------------------------
497
498 Then, you would define a "diff.tex.xfuncname" configuration to
499 specify a regular expression that matches a line that you would
500 want to appear as the hunk header "TEXT". Add a section to your
501 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
502
503 ------------------------
504 [diff "tex"]
505 xfuncname = "^(\\\\(sub)*section\\{.*)$"
506 ------------------------
507
508 Note. A single level of backslashes are eaten by the
509 configuration file parser, so you would need to double the
510 backslashes; the pattern above picks a line that begins with a
511 backslash, and zero or more occurrences of `sub` followed by
512 `section` followed by open brace, to the end of line.
513
514 There are a few built-in patterns to make this easier, and `tex`
515 is one of them, so you do not have to write the above in your
516 configuration file (you still need to enable this with the
517 attribute mechanism, via `.gitattributes`). The following built in
518 patterns are available:
519
520 - `ada` suitable for source code in the Ada language.
521
522 - `bibtex` suitable for files with BibTeX coded references.
523
524 - `cpp` suitable for source code in the C and C++ languages.
525
526 - `csharp` suitable for source code in the C# language.
527
528 - `css` suitable for cascading style sheets.
529
530 - `fortran` suitable for source code in the Fortran language.
531
532 - `fountain` suitable for Fountain documents.
533
534 - `html` suitable for HTML/XHTML documents.
535
536 - `java` suitable for source code in the Java language.
537
538 - `matlab` suitable for source code in the MATLAB language.
539
540 - `objc` suitable for source code in the Objective-C language.
541
542 - `pascal` suitable for source code in the Pascal/Delphi language.
543
544 - `perl` suitable for source code in the Perl language.
545
546 - `php` suitable for source code in the PHP language.
547
548 - `python` suitable for source code in the Python language.
549
550 - `ruby` suitable for source code in the Ruby language.
551
552 - `tex` suitable for source code for LaTeX documents.
553
554
555 Customizing word diff
556 ^^^^^^^^^^^^^^^^^^^^^
557
558 You can customize the rules that `git diff --word-diff` uses to
559 split words in a line, by specifying an appropriate regular expression
560 in the "diff.*.wordRegex" configuration variable. For example, in TeX
561 a backslash followed by a sequence of letters forms a command, but
562 several such commands can be run together without intervening
563 whitespace. To separate them, use a regular expression in your
564 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
565
566 ------------------------
567 [diff "tex"]
568 wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+"
569 ------------------------
570
571 A built-in pattern is provided for all languages listed in the
572 previous section.
573
574
575 Performing text diffs of binary files
576 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
577
578 Sometimes it is desirable to see the diff of a text-converted
579 version of some binary files. For example, a word processor
580 document can be converted to an ASCII text representation, and
581 the diff of the text shown. Even though this conversion loses
582 some information, the resulting diff is useful for human
583 viewing (but cannot be applied directly).
584
585 The `textconv` config option is used to define a program for
586 performing such a conversion. The program should take a single
587 argument, the name of a file to convert, and produce the
588 resulting text on stdout.
589
590 For example, to show the diff of the exif information of a
591 file instead of the binary information (assuming you have the
592 exif tool installed), add the following section to your
593 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file):
594
595 ------------------------
596 [diff "jpg"]
597 textconv = exif
598 ------------------------
599
600 NOTE: The text conversion is generally a one-way conversion;
601 in this example, we lose the actual image contents and focus
602 just on the text data. This means that diffs generated by
603 textconv are _not_ suitable for applying. For this reason,
604 only `git diff` and the `git log` family of commands (i.e.,
605 log, whatchanged, show) will perform text conversion. `git
606 format-patch` will never generate this output. If you want to
607 send somebody a text-converted diff of a binary file (e.g.,
608 because it quickly conveys the changes you have made), you
609 should generate it separately and send it as a comment _in
610 addition to_ the usual binary diff that you might send.
611
612 Because text conversion can be slow, especially when doing a
613 large number of them with `git log -p`, Git provides a mechanism
614 to cache the output and use it in future diffs. To enable
615 caching, set the "cachetextconv" variable in your diff driver's
616 config. For example:
617
618 ------------------------
619 [diff "jpg"]
620 textconv = exif
621 cachetextconv = true
622 ------------------------
623
624 This will cache the result of running "exif" on each blob
625 indefinitely. If you change the textconv config variable for a
626 diff driver, Git will automatically invalidate the cache entries
627 and re-run the textconv filter. If you want to invalidate the
628 cache manually (e.g., because your version of "exif" was updated
629 and now produces better output), you can remove the cache
630 manually with `git update-ref -d refs/notes/textconv/jpg` (where
631 "jpg" is the name of the diff driver, as in the example above).
632
633 Choosing textconv versus external diff
634 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
635
636 If you want to show differences between binary or specially-formatted
637 blobs in your repository, you can choose to use either an external diff
638 command, or to use textconv to convert them to a diff-able text format.
639 Which method you choose depends on your exact situation.
640
641 The advantage of using an external diff command is flexibility. You are
642 not bound to find line-oriented changes, nor is it necessary for the
643 output to resemble unified diff. You are free to locate and report
644 changes in the most appropriate way for your data format.
645
646 A textconv, by comparison, is much more limiting. You provide a
647 transformation of the data into a line-oriented text format, and Git
648 uses its regular diff tools to generate the output. There are several
649 advantages to choosing this method:
650
651 1. Ease of use. It is often much simpler to write a binary to text
652 transformation than it is to perform your own diff. In many cases,
653 existing programs can be used as textconv filters (e.g., exif,
654 odt2txt).
655
656 2. Git diff features. By performing only the transformation step
657 yourself, you can still utilize many of Git's diff features,
658 including colorization, word-diff, and combined diffs for merges.
659
660 3. Caching. Textconv caching can speed up repeated diffs, such as those
661 you might trigger by running `git log -p`.
662
663
664 Marking files as binary
665 ^^^^^^^^^^^^^^^^^^^^^^^
666
667 Git usually guesses correctly whether a blob contains text or binary
668 data by examining the beginning of the contents. However, sometimes you
669 may want to override its decision, either because a blob contains binary
670 data later in the file, or because the content, while technically
671 composed of text characters, is opaque to a human reader. For example,
672 many postscript files contain only ASCII characters, but produce noisy
673 and meaningless diffs.
674
675 The simplest way to mark a file as binary is to unset the diff
676 attribute in the `.gitattributes` file:
677
678 ------------------------
679 *.ps -diff
680 ------------------------
681
682 This will cause Git to generate `Binary files differ` (or a binary
683 patch, if binary patches are enabled) instead of a regular diff.
684
685 However, one may also want to specify other diff driver attributes. For
686 example, you might want to use `textconv` to convert postscript files to
687 an ASCII representation for human viewing, but otherwise treat them as
688 binary files. You cannot specify both `-diff` and `diff=ps` attributes.
689 The solution is to use the `diff.*.binary` config option:
690
691 ------------------------
692 [diff "ps"]
693 textconv = ps2ascii
694 binary = true
695 ------------------------
696
697 Performing a three-way merge
698 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
699
700 `merge`
701 ^^^^^^^
702
703 The attribute `merge` affects how three versions of a file are
704 merged when a file-level merge is necessary during `git merge`,
705 and other commands such as `git revert` and `git cherry-pick`.
706
707 Set::
708
709 Built-in 3-way merge driver is used to merge the
710 contents in a way similar to 'merge' command of `RCS`
711 suite. This is suitable for ordinary text files.
712
713 Unset::
714
715 Take the version from the current branch as the
716 tentative merge result, and declare that the merge has
717 conflicts. This is suitable for binary files that do
718 not have a well-defined merge semantics.
719
720 Unspecified::
721
722 By default, this uses the same built-in 3-way merge
723 driver as is the case when the `merge` attribute is set.
724 However, the `merge.default` configuration variable can name
725 different merge driver to be used with paths for which the
726 `merge` attribute is unspecified.
727
728 String::
729
730 3-way merge is performed using the specified custom
731 merge driver. The built-in 3-way merge driver can be
732 explicitly specified by asking for "text" driver; the
733 built-in "take the current branch" driver can be
734 requested with "binary".
735
736
737 Built-in merge drivers
738 ^^^^^^^^^^^^^^^^^^^^^^
739
740 There are a few built-in low-level merge drivers defined that
741 can be asked for via the `merge` attribute.
742
743 text::
744
745 Usual 3-way file level merge for text files. Conflicted
746 regions are marked with conflict markers `<<<<<<<`,
747 `=======` and `>>>>>>>`. The version from your branch
748 appears before the `=======` marker, and the version
749 from the merged branch appears after the `=======`
750 marker.
751
752 binary::
753
754 Keep the version from your branch in the work tree, but
755 leave the path in the conflicted state for the user to
756 sort out.
757
758 union::
759
760 Run 3-way file level merge for text files, but take
761 lines from both versions, instead of leaving conflict
762 markers. This tends to leave the added lines in the
763 resulting file in random order and the user should
764 verify the result. Do not use this if you do not
765 understand the implications.
766
767
768 Defining a custom merge driver
769 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
770
771 The definition of a merge driver is done in the `.git/config`
772 file, not in the `gitattributes` file, so strictly speaking this
773 manual page is a wrong place to talk about it. However...
774
775 To define a custom merge driver `filfre`, add a section to your
776 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
777
778 ----------------------------------------------------------------
779 [merge "filfre"]
780 name = feel-free merge driver
781 driver = filfre %O %A %B %L %P
782 recursive = binary
783 ----------------------------------------------------------------
784
785 The `merge.*.name` variable gives the driver a human-readable
786 name.
787
788 The `merge.*.driver` variable's value is used to construct a
789 command to run to merge ancestor's version (`%O`), current
790 version (`%A`) and the other branches' version (`%B`). These
791 three tokens are replaced with the names of temporary files that
792 hold the contents of these versions when the command line is
793 built. Additionally, %L will be replaced with the conflict marker
794 size (see below).
795
796 The merge driver is expected to leave the result of the merge in
797 the file named with `%A` by overwriting it, and exit with zero
798 status if it managed to merge them cleanly, or non-zero if there
799 were conflicts.
800
801 The `merge.*.recursive` variable specifies what other merge
802 driver to use when the merge driver is called for an internal
803 merge between common ancestors, when there are more than one.
804 When left unspecified, the driver itself is used for both
805 internal merge and the final merge.
806
807 The merge driver can learn the pathname in which the merged result
808 will be stored via placeholder `%P`.
809
810
811 `conflict-marker-size`
812 ^^^^^^^^^^^^^^^^^^^^^^
813
814 This attribute controls the length of conflict markers left in
815 the work tree file during a conflicted merge. Only setting to
816 the value to a positive integer has any meaningful effect.
817
818 For example, this line in `.gitattributes` can be used to tell the merge
819 machinery to leave much longer (instead of the usual 7-character-long)
820 conflict markers when merging the file `Documentation/git-merge.txt`
821 results in a conflict.
822
823 ------------------------
824 Documentation/git-merge.txt conflict-marker-size=32
825 ------------------------
826
827
828 Checking whitespace errors
829 ~~~~~~~~~~~~~~~~~~~~~~~~~~
830
831 `whitespace`
832 ^^^^^^^^^^^^
833
834 The `core.whitespace` configuration variable allows you to define what
835 'diff' and 'apply' should consider whitespace errors for all paths in
836 the project (See linkgit:git-config[1]). This attribute gives you finer
837 control per path.
838
839 Set::
840
841 Notice all types of potential whitespace errors known to Git.
842 The tab width is taken from the value of the `core.whitespace`
843 configuration variable.
844
845 Unset::
846
847 Do not notice anything as error.
848
849 Unspecified::
850
851 Use the value of the `core.whitespace` configuration variable to
852 decide what to notice as error.
853
854 String::
855
856 Specify a comma separate list of common whitespace problems to
857 notice in the same format as the `core.whitespace` configuration
858 variable.
859
860
861 Creating an archive
862 ~~~~~~~~~~~~~~~~~~~
863
864 `export-ignore`
865 ^^^^^^^^^^^^^^^
866
867 Files and directories with the attribute `export-ignore` won't be added to
868 archive files.
869
870 `export-subst`
871 ^^^^^^^^^^^^^^
872
873 If the attribute `export-subst` is set for a file then Git will expand
874 several placeholders when adding this file to an archive. The
875 expansion depends on the availability of a commit ID, i.e., if
876 linkgit:git-archive[1] has been given a tree instead of a commit or a
877 tag then no replacement will be done. The placeholders are the same
878 as those for the option `--pretty=format:` of linkgit:git-log[1],
879 except that they need to be wrapped like this: `$Format:PLACEHOLDERS$`
880 in the file. E.g. the string `$Format:%H$` will be replaced by the
881 commit hash.
882
883
884 Packing objects
885 ~~~~~~~~~~~~~~~
886
887 `delta`
888 ^^^^^^^
889
890 Delta compression will not be attempted for blobs for paths with the
891 attribute `delta` set to false.
892
893
894 Viewing files in GUI tools
895 ~~~~~~~~~~~~~~~~~~~~~~~~~~
896
897 `encoding`
898 ^^^^^^^^^^
899
900 The value of this attribute specifies the character encoding that should
901 be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to
902 display the contents of the relevant file. Note that due to performance
903 considerations linkgit:gitk[1] does not use this attribute unless you
904 manually enable per-file encodings in its options.
905
906 If this attribute is not set or has an invalid value, the value of the
907 `gui.encoding` configuration variable is used instead
908 (See linkgit:git-config[1]).
909
910
911 USING MACRO ATTRIBUTES
912 ----------------------
913
914 You do not want any end-of-line conversions applied to, nor textual diffs
915 produced for, any binary file you track. You would need to specify e.g.
916
917 ------------
918 *.jpg -text -diff
919 ------------
920
921 but that may become cumbersome, when you have many attributes. Using
922 macro attributes, you can define an attribute that, when set, also
923 sets or unsets a number of other attributes at the same time. The
924 system knows a built-in macro attribute, `binary`:
925
926 ------------
927 *.jpg binary
928 ------------
929
930 Setting the "binary" attribute also unsets the "text" and "diff"
931 attributes as above. Note that macro attributes can only be "Set",
932 though setting one might have the effect of setting or unsetting other
933 attributes or even returning other attributes to the "Unspecified"
934 state.
935
936
937 DEFINING MACRO ATTRIBUTES
938 -------------------------
939
940 Custom macro attributes can be defined only in top-level gitattributes
941 files (`$GIT_DIR/info/attributes`, the `.gitattributes` file at the
942 top level of the working tree, or the global or system-wide
943 gitattributes files), not in `.gitattributes` files in working tree
944 subdirectories. The built-in macro attribute "binary" is equivalent
945 to:
946
947 ------------
948 [attr]binary -diff -merge -text
949 ------------
950
951
952 EXAMPLE
953 -------
954
955 If you have these three `gitattributes` file:
956
957 ----------------------------------------------------------------
958 (in $GIT_DIR/info/attributes)
959
960 a* foo !bar -baz
961
962 (in .gitattributes)
963 abc foo bar baz
964
965 (in t/.gitattributes)
966 ab* merge=filfre
967 abc -foo -bar
968 *.c frotz
969 ----------------------------------------------------------------
970
971 the attributes given to path `t/abc` are computed as follows:
972
973 1. By examining `t/.gitattributes` (which is in the same
974 directory as the path in question), Git finds that the first
975 line matches. `merge` attribute is set. It also finds that
976 the second line matches, and attributes `foo` and `bar`
977 are unset.
978
979 2. Then it examines `.gitattributes` (which is in the parent
980 directory), and finds that the first line matches, but
981 `t/.gitattributes` file already decided how `merge`, `foo`
982 and `bar` attributes should be given to this path, so it
983 leaves `foo` and `bar` unset. Attribute `baz` is set.
984
985 3. Finally it examines `$GIT_DIR/info/attributes`. This file
986 is used to override the in-tree settings. The first line is
987 a match, and `foo` is set, `bar` is reverted to unspecified
988 state, and `baz` is unset.
989
990 As the result, the attributes assignment to `t/abc` becomes:
991
992 ----------------------------------------------------------------
993 foo set to true
994 bar unspecified
995 baz set to false
996 merge set to string value "filfre"
997 frotz unspecified
998 ----------------------------------------------------------------
999
1000
1001 SEE ALSO
1002 --------
1003 linkgit:git-check-attr[1].
1004
1005 GIT
1006 ---
1007 Part of the linkgit:git[1] suite