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[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 $GIT_DIR/info/attributes, .gitattributes
11
12
13 DESCRIPTION
14 -----------
15
16 A `gitattributes` file is a simple text file that gives
17 `attributes` to pathnames.
18
19 Each line in `gitattributes` file is of form:
20
21 pattern attr1 attr2 ...
22
23 That is, a pattern followed by an attributes list,
24 separated by whitespaces. When the pattern matches the
25 path in question, the attributes listed on the line are given to
26 the path.
27
28 Each attribute can be in one of these states for a given path:
29
30 Set::
31
32 The path has the attribute with special value "true";
33 this is specified by listing only the name of the
34 attribute in the attribute list.
35
36 Unset::
37
38 The path has the attribute with special value "false";
39 this is specified by listing the name of the attribute
40 prefixed with a dash `-` in the attribute list.
41
42 Set to a value::
43
44 The path has the attribute with specified string value;
45 this is specified by listing the name of the attribute
46 followed by an equal sign `=` and its value in the
47 attribute list.
48
49 Unspecified::
50
51 No pattern matches the path, and nothing says if
52 the path has or does not have the attribute, the
53 attribute for the path is said to be Unspecified.
54
55 When more than one pattern matches the path, a later line
56 overrides an earlier line. This overriding is done per
57 attribute. The rules how the pattern matches paths are the
58 same as in `.gitignore` files; see linkgit:gitignore[5].
59
60 When deciding what attributes are assigned to a path, git
61 consults `$GIT_DIR/info/attributes` file (which has the highest
62 precedence), `.gitattributes` file in the same directory as the
63 path in question, and its parent directories up to the toplevel of the
64 work tree (the further the directory that contains `.gitattributes`
65 is from the path in question, the lower its precedence).
66
67 If you wish to affect only a single repository (i.e., to assign
68 attributes to files that are particular to one user's workflow), then
69 attributes should be placed in the `$GIT_DIR/info/attributes` file.
70 Attributes which should be version-controlled and distributed to other
71 repositories (i.e., attributes of interest to all users) should go into
72 `.gitattributes` files.
73
74 Sometimes you would need to override an setting of an attribute
75 for a path to `unspecified` state. This can be done by listing
76 the name of the attribute prefixed with an exclamation point `!`.
77
78
79 EFFECTS
80 -------
81
82 Certain operations by git can be influenced by assigning
83 particular attributes to a path. Currently, the following
84 operations are attributes-aware.
85
86 Checking-out and checking-in
87 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
88
89 These attributes affect how the contents stored in the
90 repository are copied to the working tree files when commands
91 such as 'git checkout' and 'git merge' run. They also affect how
92 git stores the contents you prepare in the working tree in the
93 repository upon 'git add' and 'git commit'.
94
95 `crlf`
96 ^^^^^^
97
98 This attribute controls the line-ending convention.
99
100 Set::
101
102 Setting the `crlf` attribute on a path is meant to mark
103 the path as a "text" file. 'core.autocrlf' conversion
104 takes place without guessing the content type by
105 inspection.
106
107 Unset::
108
109 Unsetting the `crlf` attribute on a path tells git not to
110 attempt any end-of-line conversion upon checkin or checkout.
111
112 Unspecified::
113
114 Unspecified `crlf` attribute tells git to apply the
115 `core.autocrlf` conversion when the file content looks
116 like text.
117
118 Set to string value "input"::
119
120 This is similar to setting the attribute to `true`, but
121 also forces git to act as if `core.autocrlf` is set to
122 `input` for the path.
123
124 Any other value set to `crlf` attribute is ignored and git acts
125 as if the attribute is left unspecified.
126
127
128 The `core.autocrlf` conversion
129 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
130
131 If the configuration variable `core.autocrlf` is false, no
132 conversion is done.
133
134 When `core.autocrlf` is true, it means that the platform wants
135 CRLF line endings for files in the working tree, and you want to
136 convert them back to the normal LF line endings when checking
137 in to the repository.
138
139 When `core.autocrlf` is set to "input", line endings are
140 converted to LF upon checkin, but there is no conversion done
141 upon checkout.
142
143 If `core.safecrlf` is set to "true" or "warn", git verifies if
144 the conversion is reversible for the current setting of
145 `core.autocrlf`. For "true", git rejects irreversible
146 conversions; for "warn", git only prints a warning but accepts
147 an irreversible conversion. The safety triggers to prevent such
148 a conversion done to the files in the work tree, but there are a
149 few exceptions. Even though...
150
151 - 'git add' itself does not touch the files in the work tree, the
152 next checkout would, so the safety triggers;
153
154 - 'git apply' to update a text file with a patch does touch the files
155 in the work tree, but the operation is about text files and CRLF
156 conversion is about fixing the line ending inconsistencies, so the
157 safety does not trigger;
158
159 - 'git diff' itself does not touch the files in the work tree, it is
160 often run to inspect the changes you intend to next 'git add'. To
161 catch potential problems early, safety triggers.
162
163
164 `ident`
165 ^^^^^^^
166
167 When the attribute `ident` is set for a path, git replaces
168 `$Id$` in the blob object with `$Id:`, followed by the
169 40-character hexadecimal blob object name, followed by a dollar
170 sign `$` upon checkout. Any byte sequence that begins with
171 `$Id:` and ends with `$` in the worktree file is replaced
172 with `$Id$` upon check-in.
173
174
175 `filter`
176 ^^^^^^^^
177
178 A `filter` attribute can be set to a string value that names a
179 filter driver specified in the configuration.
180
181 A filter driver consists of a `clean` command and a `smudge`
182 command, either of which can be left unspecified. Upon
183 checkout, when the `smudge` command is specified, the command is
184 fed the blob object from its standard input, and its standard
185 output is used to update the worktree file. Similarly, the
186 `clean` command is used to convert the contents of worktree file
187 upon checkin.
188
189 A missing filter driver definition in the config is not an error
190 but makes the filter a no-op passthru.
191
192 The content filtering is done to massage the content into a
193 shape that is more convenient for the platform, filesystem, and
194 the user to use. The key phrase here is "more convenient" and not
195 "turning something unusable into usable". In other words, the
196 intent is that if someone unsets the filter driver definition,
197 or does not have the appropriate filter program, the project
198 should still be usable.
199
200 For example, in .gitattributes, you would assign the `filter`
201 attribute for paths.
202
203 ------------------------
204 *.c filter=indent
205 ------------------------
206
207 Then you would define a "filter.indent.clean" and "filter.indent.smudge"
208 configuration in your .git/config to specify a pair of commands to
209 modify the contents of C programs when the source files are checked
210 in ("clean" is run) and checked out (no change is made because the
211 command is "cat").
212
213 ------------------------
214 [filter "indent"]
215 clean = indent
216 smudge = cat
217 ------------------------
218
219
220 Interaction between checkin/checkout attributes
221 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
222
223 In the check-in codepath, the worktree file is first converted
224 with `filter` driver (if specified and corresponding driver
225 defined), then the result is processed with `ident` (if
226 specified), and then finally with `crlf` (again, if specified
227 and applicable).
228
229 In the check-out codepath, the blob content is first converted
230 with `crlf`, and then `ident` and fed to `filter`.
231
232
233 Generating diff text
234 ~~~~~~~~~~~~~~~~~~~~
235
236 `diff`
237 ^^^^^^
238
239 The attribute `diff` affects how 'git' generates diffs for particular
240 files. It can tell git whether to generate a textual patch for the path
241 or to treat the path as a binary file. It can also affect what line is
242 shown on the hunk header `@@ -k,l +n,m @@` line, tell git to use an
243 external command to generate the diff, or ask git to convert binary
244 files to a text format before generating the diff.
245
246 Set::
247
248 A path to which the `diff` attribute is set is treated
249 as text, even when they contain byte values that
250 normally never appear in text files, such as NUL.
251
252 Unset::
253
254 A path to which the `diff` attribute is unset will
255 generate `Binary files differ` (or a binary patch, if
256 binary patches are enabled).
257
258 Unspecified::
259
260 A path to which the `diff` attribute is unspecified
261 first gets its contents inspected, and if it looks like
262 text, it is treated as text. Otherwise it would
263 generate `Binary files differ`.
264
265 String::
266
267 Diff is shown using the specified diff driver. Each driver may
268 specify one or more options, as described in the following
269 section. The options for the diff driver "foo" are defined
270 by the configuration variables in the "diff.foo" section of the
271 git config file.
272
273
274 Defining an external diff driver
275 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
276
277 The definition of a diff driver is done in `gitconfig`, not
278 `gitattributes` file, so strictly speaking this manual page is a
279 wrong place to talk about it. However...
280
281 To define an external diff driver `jcdiff`, add a section to your
282 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
283
284 ----------------------------------------------------------------
285 [diff "jcdiff"]
286 command = j-c-diff
287 ----------------------------------------------------------------
288
289 When git needs to show you a diff for the path with `diff`
290 attribute set to `jcdiff`, it calls the command you specified
291 with the above configuration, i.e. `j-c-diff`, with 7
292 parameters, just like `GIT_EXTERNAL_DIFF` program is called.
293 See linkgit:git[1] for details.
294
295
296 Defining a custom hunk-header
297 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
298
299 Each group of changes (called a "hunk") in the textual diff output
300 is prefixed with a line of the form:
301
302 @@ -k,l +n,m @@ TEXT
303
304 This is called a 'hunk header'. The "TEXT" portion is by default a line
305 that begins with an alphabet, an underscore or a dollar sign; this
306 matches what GNU 'diff -p' output uses. This default selection however
307 is not suited for some contents, and you can use a customized pattern
308 to make a selection.
309
310 First, in .gitattributes, you would assign the `diff` attribute
311 for paths.
312
313 ------------------------
314 *.tex diff=tex
315 ------------------------
316
317 Then, you would define a "diff.tex.xfuncname" configuration to
318 specify a regular expression that matches a line that you would
319 want to appear as the hunk header "TEXT". Add a section to your
320 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
321
322 ------------------------
323 [diff "tex"]
324 xfuncname = "^(\\\\(sub)*section\\{.*)$"
325 ------------------------
326
327 Note. A single level of backslashes are eaten by the
328 configuration file parser, so you would need to double the
329 backslashes; the pattern above picks a line that begins with a
330 backslash, and zero or more occurrences of `sub` followed by
331 `section` followed by open brace, to the end of line.
332
333 There are a few built-in patterns to make this easier, and `tex`
334 is one of them, so you do not have to write the above in your
335 configuration file (you still need to enable this with the
336 attribute mechanism, via `.gitattributes`). The following built in
337 patterns are available:
338
339 - `bibtex` suitable for files with BibTeX coded references.
340
341 - `cpp` suitable for source code in the C and C++ languages.
342
343 - `html` suitable for HTML/XHTML documents.
344
345 - `java` suitable for source code in the Java language.
346
347 - `objc` suitable for source code in the Objective-C language.
348
349 - `pascal` suitable for source code in the Pascal/Delphi language.
350
351 - `php` suitable for source code in the PHP language.
352
353 - `python` suitable for source code in the Python language.
354
355 - `ruby` suitable for source code in the Ruby language.
356
357 - `tex` suitable for source code for LaTeX documents.
358
359
360 Customizing word diff
361 ^^^^^^^^^^^^^^^^^^^^^
362
363 You can customize the rules that `git diff --color-words` uses to
364 split words in a line, by specifying an appropriate regular expression
365 in the "diff.*.wordRegex" configuration variable. For example, in TeX
366 a backslash followed by a sequence of letters forms a command, but
367 several such commands can be run together without intervening
368 whitespace. To separate them, use a regular expression in your
369 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
370
371 ------------------------
372 [diff "tex"]
373 wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+"
374 ------------------------
375
376 A built-in pattern is provided for all languages listed in the
377 previous section.
378
379
380 Performing text diffs of binary files
381 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
382
383 Sometimes it is desirable to see the diff of a text-converted
384 version of some binary files. For example, a word processor
385 document can be converted to an ASCII text representation, and
386 the diff of the text shown. Even though this conversion loses
387 some information, the resulting diff is useful for human
388 viewing (but cannot be applied directly).
389
390 The `textconv` config option is used to define a program for
391 performing such a conversion. The program should take a single
392 argument, the name of a file to convert, and produce the
393 resulting text on stdout.
394
395 For example, to show the diff of the exif information of a
396 file instead of the binary information (assuming you have the
397 exif tool installed), add the following section to your
398 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file):
399
400 ------------------------
401 [diff "jpg"]
402 textconv = exif
403 ------------------------
404
405 NOTE: The text conversion is generally a one-way conversion;
406 in this example, we lose the actual image contents and focus
407 just on the text data. This means that diffs generated by
408 textconv are _not_ suitable for applying. For this reason,
409 only `git diff` and the `git log` family of commands (i.e.,
410 log, whatchanged, show) will perform text conversion. `git
411 format-patch` will never generate this output. If you want to
412 send somebody a text-converted diff of a binary file (e.g.,
413 because it quickly conveys the changes you have made), you
414 should generate it separately and send it as a comment _in
415 addition to_ the usual binary diff that you might send.
416
417
418 Performing a three-way merge
419 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
420
421 `merge`
422 ^^^^^^^
423
424 The attribute `merge` affects how three versions of a file is
425 merged when a file-level merge is necessary during `git merge`,
426 and other commands such as `git revert` and `git cherry-pick`.
427
428 Set::
429
430 Built-in 3-way merge driver is used to merge the
431 contents in a way similar to 'merge' command of `RCS`
432 suite. This is suitable for ordinary text files.
433
434 Unset::
435
436 Take the version from the current branch as the
437 tentative merge result, and declare that the merge has
438 conflicts. This is suitable for binary files that does
439 not have a well-defined merge semantics.
440
441 Unspecified::
442
443 By default, this uses the same built-in 3-way merge
444 driver as is the case the `merge` attribute is set.
445 However, `merge.default` configuration variable can name
446 different merge driver to be used for paths to which the
447 `merge` attribute is unspecified.
448
449 String::
450
451 3-way merge is performed using the specified custom
452 merge driver. The built-in 3-way merge driver can be
453 explicitly specified by asking for "text" driver; the
454 built-in "take the current branch" driver can be
455 requested with "binary".
456
457
458 Built-in merge drivers
459 ^^^^^^^^^^^^^^^^^^^^^^
460
461 There are a few built-in low-level merge drivers defined that
462 can be asked for via the `merge` attribute.
463
464 text::
465
466 Usual 3-way file level merge for text files. Conflicted
467 regions are marked with conflict markers `<<<<<<<`,
468 `=======` and `>>>>>>>`. The version from your branch
469 appears before the `=======` marker, and the version
470 from the merged branch appears after the `=======`
471 marker.
472
473 binary::
474
475 Keep the version from your branch in the work tree, but
476 leave the path in the conflicted state for the user to
477 sort out.
478
479 union::
480
481 Run 3-way file level merge for text files, but take
482 lines from both versions, instead of leaving conflict
483 markers. This tends to leave the added lines in the
484 resulting file in random order and the user should
485 verify the result. Do not use this if you do not
486 understand the implications.
487
488
489 Defining a custom merge driver
490 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
491
492 The definition of a merge driver is done in the `.git/config`
493 file, not in the `gitattributes` file, so strictly speaking this
494 manual page is a wrong place to talk about it. However...
495
496 To define a custom merge driver `filfre`, add a section to your
497 `$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
498
499 ----------------------------------------------------------------
500 [merge "filfre"]
501 name = feel-free merge driver
502 driver = filfre %O %A %B
503 recursive = binary
504 ----------------------------------------------------------------
505
506 The `merge.*.name` variable gives the driver a human-readable
507 name.
508
509 The `merge.*.driver` variable's value is used to construct a
510 command to run to merge ancestor's version (`%O`), current
511 version (`%A`) and the other branches' version (`%B`). These
512 three tokens are replaced with the names of temporary files that
513 hold the contents of these versions when the command line is
514 built. Additionally, %L will be replaced with the conflict marker
515 size (see below).
516
517 The merge driver is expected to leave the result of the merge in
518 the file named with `%A` by overwriting it, and exit with zero
519 status if it managed to merge them cleanly, or non-zero if there
520 were conflicts.
521
522 The `merge.*.recursive` variable specifies what other merge
523 driver to use when the merge driver is called for an internal
524 merge between common ancestors, when there are more than one.
525 When left unspecified, the driver itself is used for both
526 internal merge and the final merge.
527
528
529 `conflict-marker-size`
530 ^^^^^^^^^^^^^^^^^^^^^^
531
532 This attribute controls the length of conflict markers left in
533 the work tree file during a conflicted merge. Only setting to
534 the value to a positive integer has any meaningful effect.
535
536 For example, this line in `.gitattributes` can be used to tell the merge
537 machinery to leave much longer (instead of the usual 7-character-long)
538 conflict markers when merging the file `Documentation/git-merge.txt`
539 results in a conflict.
540
541 ------------------------
542 Documentation/git-merge.txt conflict-marker-size=32
543 ------------------------
544
545
546 Checking whitespace errors
547 ~~~~~~~~~~~~~~~~~~~~~~~~~~
548
549 `whitespace`
550 ^^^^^^^^^^^^
551
552 The `core.whitespace` configuration variable allows you to define what
553 'diff' and 'apply' should consider whitespace errors for all paths in
554 the project (See linkgit:git-config[1]). This attribute gives you finer
555 control per path.
556
557 Set::
558
559 Notice all types of potential whitespace errors known to git.
560
561 Unset::
562
563 Do not notice anything as error.
564
565 Unspecified::
566
567 Use the value of `core.whitespace` configuration variable to
568 decide what to notice as error.
569
570 String::
571
572 Specify a comma separate list of common whitespace problems to
573 notice in the same format as `core.whitespace` configuration
574 variable.
575
576
577 Creating an archive
578 ~~~~~~~~~~~~~~~~~~~
579
580 `export-ignore`
581 ^^^^^^^^^^^^^^^
582
583 Files and directories with the attribute `export-ignore` won't be added to
584 archive files.
585
586 `export-subst`
587 ^^^^^^^^^^^^^^
588
589 If the attribute `export-subst` is set for a file then git will expand
590 several placeholders when adding this file to an archive. The
591 expansion depends on the availability of a commit ID, i.e., if
592 linkgit:git-archive[1] has been given a tree instead of a commit or a
593 tag then no replacement will be done. The placeholders are the same
594 as those for the option `--pretty=format:` of linkgit:git-log[1],
595 except that they need to be wrapped like this: `$Format:PLACEHOLDERS$`
596 in the file. E.g. the string `$Format:%H$` will be replaced by the
597 commit hash.
598
599
600 Packing objects
601 ~~~~~~~~~~~~~~~
602
603 `delta`
604 ^^^^^^^
605
606 Delta compression will not be attempted for blobs for paths with the
607 attribute `delta` set to false.
608
609
610 Viewing files in GUI tools
611 ~~~~~~~~~~~~~~~~~~~~~~~~~~
612
613 `encoding`
614 ^^^^^^^^^^
615
616 The value of this attribute specifies the character encoding that should
617 be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to
618 display the contents of the relevant file. Note that due to performance
619 considerations linkgit:gitk[1] does not use this attribute unless you
620 manually enable per-file encodings in its options.
621
622 If this attribute is not set or has an invalid value, the value of the
623 `gui.encoding` configuration variable is used instead
624 (See linkgit:git-config[1]).
625
626
627 USING ATTRIBUTE MACROS
628 ----------------------
629
630 You do not want any end-of-line conversions applied to, nor textual diffs
631 produced for, any binary file you track. You would need to specify e.g.
632
633 ------------
634 *.jpg -crlf -diff
635 ------------
636
637 but that may become cumbersome, when you have many attributes. Using
638 attribute macros, you can specify groups of attributes set or unset at
639 the same time. The system knows a built-in attribute macro, `binary`:
640
641 ------------
642 *.jpg binary
643 ------------
644
645 which is equivalent to the above. Note that the attribute macros can only
646 be "Set" (see the above example that sets "binary" macro as if it were an
647 ordinary attribute --- setting it in turn unsets "crlf" and "diff").
648
649
650 DEFINING ATTRIBUTE MACROS
651 -------------------------
652
653 Custom attribute macros can be defined only in the `.gitattributes` file
654 at the toplevel (i.e. not in any subdirectory). The built-in attribute
655 macro "binary" is equivalent to:
656
657 ------------
658 [attr]binary -diff -crlf
659 ------------
660
661
662 EXAMPLE
663 -------
664
665 If you have these three `gitattributes` file:
666
667 ----------------------------------------------------------------
668 (in $GIT_DIR/info/attributes)
669
670 a* foo !bar -baz
671
672 (in .gitattributes)
673 abc foo bar baz
674
675 (in t/.gitattributes)
676 ab* merge=filfre
677 abc -foo -bar
678 *.c frotz
679 ----------------------------------------------------------------
680
681 the attributes given to path `t/abc` are computed as follows:
682
683 1. By examining `t/.gitattributes` (which is in the same
684 directory as the path in question), git finds that the first
685 line matches. `merge` attribute is set. It also finds that
686 the second line matches, and attributes `foo` and `bar`
687 are unset.
688
689 2. Then it examines `.gitattributes` (which is in the parent
690 directory), and finds that the first line matches, but
691 `t/.gitattributes` file already decided how `merge`, `foo`
692 and `bar` attributes should be given to this path, so it
693 leaves `foo` and `bar` unset. Attribute `baz` is set.
694
695 3. Finally it examines `$GIT_DIR/info/attributes`. This file
696 is used to override the in-tree settings. The first line is
697 a match, and `foo` is set, `bar` is reverted to unspecified
698 state, and `baz` is unset.
699
700 As the result, the attributes assignment to `t/abc` becomes:
701
702 ----------------------------------------------------------------
703 foo set to true
704 bar unspecified
705 baz set to false
706 merge set to string value "filfre"
707 frotz unspecified
708 ----------------------------------------------------------------
709
710
711
712 GIT
713 ---
714 Part of the linkgit:git[1] suite