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