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1gitattributes(5)
2================
3
4NAME
5----
6gitattributes - Defining attributes per path
7
8SYNOPSIS
9--------
10$GIT_DIR/info/attributes, .gitattributes
11
12
13DESCRIPTION
14-----------
15
16A `gitattributes` file is a simple text file that gives
17`attributes` to pathnames.
18
19Each line in `gitattributes` file is of form:
20
21 pattern attr1 attr2 ...
22
23That is, a pattern followed by an attributes list,
24separated by whitespaces. Leading and trailing whitespaces are
25ignored. Lines that begin with '#' are ignored. Patterns
26that begin with a double quote are quoted in C style.
27When the pattern matches the path in question, the attributes
28listed on the line are given to the path.
29
30Each attribute can be in one of these states for a given path:
31
32Set::
33
34 The path has the attribute with special value "true";
35 this is specified by listing only the name of the
36 attribute in the attribute list.
37
38Unset::
39
40 The path has the attribute with special value "false";
41 this is specified by listing the name of the attribute
42 prefixed with a dash `-` in the attribute list.
43
44Set to a value::
45
46 The path has the attribute with specified string value;
47 this is specified by listing the name of the attribute
48 followed by an equal sign `=` and its value in the
49 attribute list.
50
51Unspecified::
52
53 No pattern matches the path, and nothing says if
54 the path has or does not have the attribute, the
55 attribute for the path is said to be Unspecified.
56
57When more than one pattern matches the path, a later line
58overrides an earlier line. This overriding is done per
59attribute.
60
61The rules by which the pattern matches paths are the same as in
62`.gitignore` files (see linkgit:gitignore[5]), with a few exceptions:
63
64 - negative patterns are forbidden
65
66 - patterns that match a directory do not recursively match paths
67 inside that directory (so using the trailing-slash `path/` syntax is
68 pointless in an attributes file; use `path/**` instead)
69
70When deciding what attributes are assigned to a path, Git
71consults `$GIT_DIR/info/attributes` file (which has the highest
72precedence), `.gitattributes` file in the same directory as the
73path in question, and its parent directories up to the toplevel of the
74work tree (the further the directory that contains `.gitattributes`
75is from the path in question, the lower its precedence). Finally
76global and system-wide files are considered (they have the lowest
77precedence).
78
79When the `.gitattributes` file is missing from the work tree, the
80path in the index is used as a fall-back. During checkout process,
81`.gitattributes` in the index is used and then the file in the
82working tree is used as a fall-back.
83
84If you wish to affect only a single repository (i.e., to assign
85attributes to files that are particular to
86one user's workflow for that repository), then
87attributes should be placed in the `$GIT_DIR/info/attributes` file.
88Attributes which should be version-controlled and distributed to other
89repositories (i.e., attributes of interest to all users) should go into
90`.gitattributes` files. Attributes that should affect all repositories
91for a single user should be placed in a file specified by the
92`core.attributesFile` configuration option (see linkgit:git-config[1]).
93Its default value is $XDG_CONFIG_HOME/git/attributes. If $XDG_CONFIG_HOME
94is either not set or empty, $HOME/.config/git/attributes is used instead.
95Attributes for all users on a system should be placed in the
96`$(prefix)/etc/gitattributes` file.
97
98Sometimes you would need to override a setting of an attribute
99for a path to `Unspecified` state. This can be done by listing
100the name of the attribute prefixed with an exclamation point `!`.
101
102
103RESERVED BUILTIN_* ATTRIBUTES
104-----------------------------
105
106builtin_* is a reserved namespace for builtin attribute values. Any
107user defined attributes under this namespace will be ignored and
108trigger a warning.
109
110`builtin_objectmode`
111~~~~~~~~~~~~~~~~~~~~
112This attribute is for filtering files by their file bit modes (40000,
113120000, 160000, 100755, 100644). e.g. ':(attr:builtin_objectmode=160000)'.
114You may also check these values with `git check-attr builtin_objectmode -- <file>`.
115If the object is not in the index `git check-attr --cached` will return unspecified.
116
117
118EFFECTS
119-------
120
121Certain operations by Git can be influenced by assigning
122particular attributes to a path. Currently, the following
123operations are attributes-aware.
124
125Checking-out and checking-in
126~~~~~~~~~~~~~~~~~~~~~~~~~~~~
127
128These attributes affect how the contents stored in the
129repository are copied to the working tree files when commands
130such as 'git switch', 'git checkout' and 'git merge' run.
131They also affect how
132Git stores the contents you prepare in the working tree in the
133repository upon 'git add' and 'git commit'.
134
135`text`
136^^^^^^
137
138This attribute marks the path as a text file, which enables end-of-line
139conversion: When a matching file is added to the index, the file's line
140endings are normalized to LF in the index. Conversely, when the file is
141copied from the index to the working directory, its line endings may be
142converted from LF to CRLF depending on the `eol` attribute, the Git
143config, and the platform (see explanation of `eol` below).
144
145Set::
146
147 Setting the `text` attribute on a path enables end-of-line
148 conversion on checkin and checkout as described above. Line endings
149 are normalized to LF in the index every time the file is checked in,
150 even if the file was previously added to Git with CRLF line endings.
151
152Unset::
153
154 Unsetting the `text` attribute on a path tells Git not to
155 attempt any end-of-line conversion upon checkin or checkout.
156
157Set to string value "auto"::
158
159 When `text` is set to "auto", Git decides by itself whether the file
160 is text or binary. If it is text and the file was not already in
161 Git with CRLF endings, line endings are converted on checkin and
162 checkout as described above. Otherwise, no conversion is done on
163 checkin or checkout.
164
165Unspecified::
166
167 If the `text` attribute is unspecified, Git uses the
168 `core.autocrlf` configuration variable to determine if the
169 file should be converted.
170
171Any other value causes Git to act as if `text` has been left
172unspecified.
173
174`eol`
175^^^^^
176
177This attribute marks a path to use a specific line-ending style in the
178working tree when it is checked out. It has effect only if `text` or
179`text=auto` is set (see above), but specifying `eol` automatically sets
180`text` if `text` was left unspecified.
181
182Set to string value "crlf"::
183
184 This setting converts the file's line endings in the working
185 directory to CRLF when the file is checked out.
186
187Set to string value "lf"::
188
189 This setting uses the same line endings in the working directory as
190 in the index when the file is checked out.
191
192Unspecified::
193
194 If the `eol` attribute is unspecified for a file, its line endings
195 in the working directory are determined by the `core.autocrlf` or
196 `core.eol` configuration variable (see the definitions of those
197 options in linkgit:git-config[1]). If `text` is set but neither of
198 those variables is, the default is `eol=crlf` on Windows and
199 `eol=lf` on all other platforms.
200
201Backwards compatibility with `crlf` attribute
202^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
203
204For backwards compatibility, the `crlf` attribute is interpreted as
205follows:
206
207------------------------
208crlf text
209-crlf -text
210crlf=input eol=lf
211------------------------
212
213End-of-line conversion
214^^^^^^^^^^^^^^^^^^^^^^
215
216While Git normally leaves file contents alone, it can be configured to
217normalize line endings to LF in the repository and, optionally, to
218convert them to CRLF when files are checked out.
219
220If you simply want to have CRLF line endings in your working directory
221regardless of the repository you are working with, you can set the
222config variable "core.autocrlf" without using any attributes.
223
224------------------------
225[core]
226 autocrlf = true
227------------------------
228
229This does not force normalization of text files, but does ensure
230that text files that you introduce to the repository have their line
231endings normalized to LF when they are added, and that files that are
232already normalized in the repository stay normalized.
233
234If you want to ensure that text files that any contributor introduces to
235the repository have their line endings normalized, you can set the
236`text` attribute to "auto" for _all_ files.
237
238------------------------
239* text=auto
240------------------------
241
242The attributes allow a fine-grained control, how the line endings
243are converted.
244Here is an example that will make Git normalize .txt, .vcproj and .sh
245files, ensure that .vcproj files have CRLF and .sh files have LF in
246the working directory, and prevent .jpg files from being normalized
247regardless of their content.
248
249------------------------
250* text=auto
251*.txt text
252*.vcproj text eol=crlf
253*.sh text eol=lf
254*.jpg -text
255------------------------
256
257NOTE: When `text=auto` conversion is enabled in a cross-platform
258project using push and pull to a central repository the text files
259containing CRLFs should be normalized.
260
261From a clean working directory:
262
263-------------------------------------------------
264$ echo "* text=auto" >.gitattributes
265$ git add --renormalize .
266$ git status # Show files that will be normalized
267$ git commit -m "Introduce end-of-line normalization"
268-------------------------------------------------
269
270If any files that should not be normalized show up in 'git status',
271unset their `text` attribute before running 'git add -u'.
272
273------------------------
274manual.pdf -text
275------------------------
276
277Conversely, text files that Git does not detect can have normalization
278enabled manually.
279
280------------------------
281weirdchars.txt text
282------------------------
283
284If `core.safecrlf` is set to "true" or "warn", Git verifies if
285the conversion is reversible for the current setting of
286`core.autocrlf`. For "true", Git rejects irreversible
287conversions; for "warn", Git only prints a warning but accepts
288an irreversible conversion. The safety triggers to prevent such
289a conversion done to the files in the work tree, but there are a
290few exceptions. Even though...
291
292- 'git add' itself does not touch the files in the work tree, the
293 next checkout would, so the safety triggers;
294
295- 'git apply' to update a text file with a patch does touch the files
296 in the work tree, but the operation is about text files and CRLF
297 conversion is about fixing the line ending inconsistencies, so the
298 safety does not trigger;
299
300- 'git diff' itself does not touch the files in the work tree, it is
301 often run to inspect the changes you intend to next 'git add'. To
302 catch potential problems early, safety triggers.
303
304
305`working-tree-encoding`
306^^^^^^^^^^^^^^^^^^^^^^^
307
308Git recognizes files encoded in ASCII or one of its supersets (e.g.
309UTF-8, ISO-8859-1, ...) as text files. Files encoded in certain other
310encodings (e.g. UTF-16) are interpreted as binary and consequently
311built-in Git text processing tools (e.g. 'git diff') as well as most Git
312web front ends do not visualize the contents of these files by default.
313
314In these cases you can tell Git the encoding of a file in the working
315directory with the `working-tree-encoding` attribute. If a file with this
316attribute is added to Git, then Git re-encodes the content from the
317specified encoding to UTF-8. Finally, Git stores the UTF-8 encoded
318content in its internal data structure (called "the index"). On checkout
319the content is re-encoded back to the specified encoding.
320
321Please note that using the `working-tree-encoding` attribute may have a
322number of pitfalls:
323
324- Alternative Git implementations (e.g. JGit or libgit2) and older Git
325 versions (as of March 2018) do not support the `working-tree-encoding`
326 attribute. If you decide to use the `working-tree-encoding` attribute
327 in your repository, then it is strongly recommended to ensure that all
328 clients working with the repository support it.
329+
330For example, Microsoft Visual Studio resources files (`*.rc`) or
331PowerShell script files (`*.ps1`) are sometimes encoded in UTF-16.
332If you declare `*.ps1` as files as UTF-16 and you add `foo.ps1` with
333a `working-tree-encoding` enabled Git client, then `foo.ps1` will be
334stored as UTF-8 internally. A client without `working-tree-encoding`
335support will checkout `foo.ps1` as UTF-8 encoded file. This will
336typically cause trouble for the users of this file.
337+
338If a Git client that does not support the `working-tree-encoding`
339attribute adds a new file `bar.ps1`, then `bar.ps1` will be
340stored "as-is" internally (in this example probably as UTF-16).
341A client with `working-tree-encoding` support will interpret the
342internal contents as UTF-8 and try to convert it to UTF-16 on checkout.
343That operation will fail and cause an error.
344
345- Reencoding content to non-UTF encodings can cause errors as the
346 conversion might not be UTF-8 round trip safe. If you suspect your
347 encoding to not be round trip safe, then add it to
348 `core.checkRoundtripEncoding` to make Git check the round trip
349 encoding (see linkgit:git-config[1]). SHIFT-JIS (Japanese character
350 set) is known to have round trip issues with UTF-8 and is checked by
351 default.
352
353- Reencoding content requires resources that might slow down certain
354 Git operations (e.g 'git checkout' or 'git add').
355
356Use the `working-tree-encoding` attribute only if you cannot store a file
357in UTF-8 encoding and if you want Git to be able to process the content
358as text.
359
360As an example, use the following attributes if your '*.ps1' files are
361UTF-16 encoded with byte order mark (BOM) and you want Git to perform
362automatic line ending conversion based on your platform.
363
364------------------------
365*.ps1 text working-tree-encoding=UTF-16
366------------------------
367
368Use the following attributes if your '*.ps1' files are UTF-16 little
369endian encoded without BOM and you want Git to use Windows line endings
370in the working directory (use `UTF-16LE-BOM` instead of `UTF-16LE` if
371you want UTF-16 little endian with BOM).
372Please note, it is highly recommended to
373explicitly define the line endings with `eol` if the `working-tree-encoding`
374attribute is used to avoid ambiguity.
375
376------------------------
377*.ps1 text working-tree-encoding=UTF-16LE eol=crlf
378------------------------
379
380You can get a list of all available encodings on your platform with the
381following command:
382
383------------------------
384iconv --list
385------------------------
386
387If you do not know the encoding of a file, then you can use the `file`
388command to guess the encoding:
389
390------------------------
391file foo.ps1
392------------------------
393
394
395`ident`
396^^^^^^^
397
398When the attribute `ident` is set for a path, Git replaces
399`$Id$` in the blob object with `$Id:`, followed by the
40040-character hexadecimal blob object name, followed by a dollar
401sign `$` upon checkout. Any byte sequence that begins with
402`$Id:` and ends with `$` in the worktree file is replaced
403with `$Id$` upon check-in.
404
405
406`filter`
407^^^^^^^^
408
409A `filter` attribute can be set to a string value that names a
410filter driver specified in the configuration.
411
412A filter driver consists of a `clean` command and a `smudge`
413command, either of which can be left unspecified. Upon
414checkout, when the `smudge` command is specified, the command is
415fed the blob object from its standard input, and its standard
416output is used to update the worktree file. Similarly, the
417`clean` command is used to convert the contents of worktree file
418upon checkin. By default these commands process only a single
419blob and terminate. If a long running `process` filter is used
420in place of `clean` and/or `smudge` filters, then Git can process
421all blobs with a single filter command invocation for the entire
422life of a single Git command, for example `git add --all`. If a
423long running `process` filter is configured then it always takes
424precedence over a configured single blob filter. See section
425below for the description of the protocol used to communicate with
426a `process` filter.
427
428One use of the content filtering is to massage the content into a shape
429that is more convenient for the platform, filesystem, and the user to use.
430For this mode of operation, the key phrase here is "more convenient" and
431not "turning something unusable into usable". In other words, the intent
432is that if someone unsets the filter driver definition, or does not have
433the appropriate filter program, the project should still be usable.
434
435Another use of the content filtering is to store the content that cannot
436be directly used in the repository (e.g. a UUID that refers to the true
437content stored outside Git, or an encrypted content) and turn it into a
438usable form upon checkout (e.g. download the external content, or decrypt
439the encrypted content).
440
441These two filters behave differently, and by default, a filter is taken as
442the former, massaging the contents into more convenient shape. A missing
443filter driver definition in the config, or a filter driver that exits with
444a non-zero status, is not an error but makes the filter a no-op passthru.
445
446You can declare that a filter turns a content that by itself is unusable
447into a usable content by setting the filter.<driver>.required configuration
448variable to `true`.
449
450Note: Whenever the clean filter is changed, the repo should be renormalized:
451$ git add --renormalize .
452
453For example, in .gitattributes, you would assign the `filter`
454attribute for paths.
455
456------------------------
457*.c filter=indent
458------------------------
459
460Then you would define a "filter.indent.clean" and "filter.indent.smudge"
461configuration in your .git/config to specify a pair of commands to
462modify the contents of C programs when the source files are checked
463in ("clean" is run) and checked out (no change is made because the
464command is "cat").
465
466------------------------
467[filter "indent"]
468 clean = indent
469 smudge = cat
470------------------------
471
472For best results, `clean` should not alter its output further if it is
473run twice ("clean->clean" should be equivalent to "clean"), and
474multiple `smudge` commands should not alter `clean`'s output
475("smudge->smudge->clean" should be equivalent to "clean"). See the
476section on merging below.
477
478The "indent" filter is well-behaved in this regard: it will not modify
479input that is already correctly indented. In this case, the lack of a
480smudge filter means that the clean filter _must_ accept its own output
481without modifying it.
482
483If a filter _must_ succeed in order to make the stored contents usable,
484you can declare that the filter is `required`, in the configuration:
485
486------------------------
487[filter "crypt"]
488 clean = openssl enc ...
489 smudge = openssl enc -d ...
490 required
491------------------------
492
493Sequence "%f" on the filter command line is replaced with the name of
494the file the filter is working on. A filter might use this in keyword
495substitution. For example:
496
497------------------------
498[filter "p4"]
499 clean = git-p4-filter --clean %f
500 smudge = git-p4-filter --smudge %f
501------------------------
502
503Note that "%f" is the name of the path that is being worked on. Depending
504on the version that is being filtered, the corresponding file on disk may
505not exist, or may have different contents. So, smudge and clean commands
506should not try to access the file on disk, but only act as filters on the
507content provided to them on standard input.
508
509Long Running Filter Process
510^^^^^^^^^^^^^^^^^^^^^^^^^^^
511
512If the filter command (a string value) is defined via
513`filter.<driver>.process` then Git can process all blobs with a
514single filter invocation for the entire life of a single Git
515command. This is achieved by using the long-running process protocol
516(described in Documentation/technical/long-running-process-protocol.adoc).
517
518When Git encounters the first file that needs to be cleaned or smudged,
519it starts the filter and performs the handshake. In the handshake, the
520welcome message sent by Git is "git-filter-client", only version 2 is
521supported, and the supported capabilities are "clean", "smudge", and
522"delay".
523
524Afterwards Git sends a list of "key=value" pairs terminated with
525a flush packet. The list will contain at least the filter command
526(based on the supported capabilities) and the pathname of the file
527to filter relative to the repository root. Right after the flush packet
528Git sends the content split in zero or more pkt-line packets and a
529flush packet to terminate content. Please note, that the filter
530must not send any response before it received the content and the
531final flush packet. Also note that the "value" of a "key=value" pair
532can contain the "=" character whereas the key would never contain
533that character.
534
535-----------------------
536packet: git> command=smudge
537packet: git> pathname=path/testfile.dat
538packet: git> 0000
539packet: git> CONTENT
540packet: git> 0000
541-----------------------
542
543The filter is expected to respond with a list of "key=value" pairs
544terminated with a flush packet. If the filter does not experience
545problems then the list must contain a "success" status. Right after
546these packets the filter is expected to send the content in zero
547or more pkt-line packets and a flush packet at the end. Finally, a
548second list of "key=value" pairs terminated with a flush packet
549is expected. The filter can change the status in the second list
550or keep the status as is with an empty list. Please note that the
551empty list must be terminated with a flush packet regardless.
552
553------------------------
554packet: git< status=success
555packet: git< 0000
556packet: git< SMUDGED_CONTENT
557packet: git< 0000
558packet: git< 0000 # empty list, keep "status=success" unchanged!
559------------------------
560
561If the result content is empty then the filter is expected to respond
562with a "success" status and a flush packet to signal the empty content.
563
564------------------------
565packet: git< status=success
566packet: git< 0000
567packet: git< 0000 # empty content!
568packet: git< 0000 # empty list, keep "status=success" unchanged!
569------------------------
570
571In case the filter cannot or does not want to process the content,
572it is expected to respond with an "error" status.
573
574-----------------------
575packet: git< status=error
576packet: git< 0000
577-----------------------
578
579If the filter experiences an error during processing, then it can
580send the status "error" after the content was (partially or
581completely) sent.
582
583------------------------
584packet: git< status=success
585packet: git< 0000
586packet: git< HALF_WRITTEN_ERRONEOUS_CONTENT
587packet: git< 0000
588packet: git< status=error
589packet: git< 0000
590------------------------
591
592In case the filter cannot or does not want to process the content
593as well as any future content for the lifetime of the Git process,
594then it is expected to respond with an "abort" status at any point
595in the protocol.
596
597-----------------------
598packet: git< status=abort
599packet: git< 0000
600-----------------------
601
602Git neither stops nor restarts the filter process in case the
603"error"/"abort" status is set. However, Git sets its exit code
604according to the `filter.<driver>.required` flag, mimicking the
605behavior of the `filter.<driver>.clean` / `filter.<driver>.smudge`
606mechanism.
607
608If the filter dies during the communication or does not adhere to
609the protocol then Git will stop the filter process and restart it
610with the next file that needs to be processed. Depending on the
611`filter.<driver>.required` flag Git will interpret that as error.
612
613Delay
614^^^^^
615
616If the filter supports the "delay" capability, then Git can send the
617flag "can-delay" after the filter command and pathname. This flag
618denotes that the filter can delay filtering the current blob (e.g. to
619compensate network latencies) by responding with no content but with
620the status "delayed" and a flush packet.
621
622-----------------------
623packet: git> command=smudge
624packet: git> pathname=path/testfile.dat
625packet: git> can-delay=1
626packet: git> 0000
627packet: git> CONTENT
628packet: git> 0000
629packet: git< status=delayed
630packet: git< 0000
631-----------------------
632
633If the filter supports the "delay" capability then it must support the
634"list_available_blobs" command. If Git sends this command, then the
635filter is expected to return a list of pathnames representing blobs
636that have been delayed earlier and are now available.
637The list must be terminated with a flush packet followed
638by a "success" status that is also terminated with a flush packet. If
639no blobs for the delayed paths are available, yet, then the filter is
640expected to block the response until at least one blob becomes
641available. The filter can tell Git that it has no more delayed blobs
642by sending an empty list. As soon as the filter responds with an empty
643list, Git stops asking. All blobs that Git has not received at this
644point are considered missing and will result in an error.
645
646------------------------
647packet: git> command=list_available_blobs
648packet: git> 0000
649packet: git< pathname=path/testfile.dat
650packet: git< pathname=path/otherfile.dat
651packet: git< 0000
652packet: git< status=success
653packet: git< 0000
654------------------------
655
656
657After Git received the pathnames, it will request the corresponding
658blobs again. These requests contain a pathname and an empty content
659section. The filter is expected to respond with the smudged content
660in the usual way as explained above.
661
662------------------------
663packet: git> command=smudge
664packet: git> pathname=path/testfile.dat
665packet: git> 0000
666packet: git> 0000 # empty content!
667packet: git< status=success
668packet: git< 0000
669packet: git< SMUDGED_CONTENT
670packet: git< 0000
671packet: git< 0000 # empty list, keep "status=success" unchanged!
672------------------------
673
674Example
675^^^^^^^
676
677A long running filter demo implementation can be found in
678`contrib/long-running-filter/example.pl` located in the Git
679core repository. If you develop your own long running filter
680process then the `GIT_TRACE_PACKET` environment variables can be
681very helpful for debugging (see linkgit:git[1]).
682
683Please note that you cannot use an existing `filter.<driver>.clean`
684or `filter.<driver>.smudge` command with `filter.<driver>.process`
685because the former two use a different inter process communication
686protocol than the latter one.
687
688
689Interaction between checkin/checkout attributes
690^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
691
692In the check-in codepath, the worktree file is first converted
693with `filter` driver (if specified and corresponding driver
694defined), then the result is processed with `ident` (if
695specified), and then finally with `text` (again, if specified
696and applicable).
697
698In the check-out codepath, the blob content is first converted
699with `text`, and then `ident` and fed to `filter`.
700
701
702Merging branches with differing checkin/checkout attributes
703^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
704
705If you have added attributes to a file that cause the canonical
706repository format for that file to change, such as adding a
707clean/smudge filter or text/eol/ident attributes, merging anything
708where the attribute is not in place would normally cause merge
709conflicts.
710
711To prevent these unnecessary merge conflicts, Git can be told to run a
712virtual check-out and check-in of all three stages of each file that
713needs a three-way content merge, by setting the `merge.renormalize`
714configuration variable. This prevents changes caused by check-in
715conversion from causing spurious merge conflicts when a converted file
716is merged with an unconverted file.
717
718As long as a "smudge->clean" results in the same output as a "clean"
719even on files that are already smudged, this strategy will
720automatically resolve all filter-related conflicts. Filters that do
721not act in this way may cause additional merge conflicts that must be
722resolved manually.
723
724
725Generating diff text
726~~~~~~~~~~~~~~~~~~~~
727
728`diff`
729^^^^^^
730
731The attribute `diff` affects how Git generates diffs for particular
732files. It can tell Git whether to generate a textual patch for the path
733or to treat the path as a binary file. It can also affect what line is
734shown on the hunk header `@@ -k,l +n,m @@` line, tell Git to use an
735external command to generate the diff, or ask Git to convert binary
736files to a text format before generating the diff.
737
738Set::
739
740 A path to which the `diff` attribute is set is treated
741 as text, even when they contain byte values that
742 normally never appear in text files, such as NUL.
743
744Unset::
745
746 A path to which the `diff` attribute is unset will
747 generate `Binary files differ` (or a binary patch, if
748 binary patches are enabled).
749
750Unspecified::
751
752 A path to which the `diff` attribute is unspecified
753 first gets its contents inspected, and if it looks like
754 text and is smaller than core.bigFileThreshold, it is treated
755 as text. Otherwise it would generate `Binary files differ`.
756
757String::
758
759 Diff is shown using the specified diff driver. Each driver may
760 specify one or more options, as described in the following
761 section. The options for the diff driver "foo" are defined
762 by the configuration variables in the "diff.foo" section of the
763 Git config file.
764
765
766Defining an external diff driver
767^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
768
769The definition of a diff driver is done in `gitconfig`, not
770`gitattributes` file, so strictly speaking this manual page is a
771wrong place to talk about it. However...
772
773To define an external diff driver `jcdiff`, add a section to your
774`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
775
776----------------------------------------------------------------
777[diff "jcdiff"]
778 command = j-c-diff
779----------------------------------------------------------------
780
781When Git needs to show you a diff for the path with `diff`
782attribute set to `jcdiff`, it calls the command you specified
783with the above configuration, i.e. `j-c-diff`, with 7
784parameters, just like `GIT_EXTERNAL_DIFF` program is called.
785See linkgit:git[1] for details.
786
787If the program is able to ignore certain changes (similar to
788`git diff --ignore-space-change`), then also set the option
789`trustExitCode` to true. It is then expected to return exit code 1 if
790it finds significant changes and 0 if it doesn't.
791
792Setting the internal diff algorithm
793^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
794
795The diff algorithm can be set through the `diff.algorithm` config key, but
796sometimes it may be helpful to set the diff algorithm per path. For example,
797one may want to use the `minimal` diff algorithm for .json files, and the
798`histogram` for .c files, and so on without having to pass in the algorithm
799through the command line each time.
800
801First, in `.gitattributes`, assign the `diff` attribute for paths.
802
803------------------------
804*.json diff=<name>
805------------------------
806
807Then, define a "diff.<name>.algorithm" configuration to specify the diff
808algorithm, choosing from `myers`, `patience`, `minimal`, or `histogram`.
809
810----------------------------------------------------------------
811[diff "<name>"]
812 algorithm = histogram
813----------------------------------------------------------------
814
815This diff algorithm applies to user facing diff output like git-diff(1),
816git-show(1) and is used for the `--stat` output as well. The merge machinery
817will not use the diff algorithm set through this method.
818
819NOTE: If `diff.<name>.command` is defined for path with the
820`diff=<name>` attribute, it is executed as an external diff driver
821(see above), and adding `diff.<name>.algorithm` has no effect, as the
822algorithm is not passed to the external diff driver.
823
824Defining a custom hunk-header
825^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
826
827Each group of changes (called a "hunk") in the textual diff output
828is prefixed with a line of the form:
829
830 @@ -k,l +n,m @@ TEXT
831
832This is called a 'hunk header'. The "TEXT" portion is by default a line
833that begins with an alphabet, an underscore or a dollar sign; this
834matches what GNU 'diff -p' output uses. This default selection however
835is not suited for some contents, and you can use a customized pattern
836to make a selection.
837
838First, in .gitattributes, you would assign the `diff` attribute
839for paths.
840
841------------------------
842*.tex diff=tex
843------------------------
844
845Then, you would define a "diff.tex.xfuncname" configuration to
846specify a regular expression that matches a line that you would
847want to appear as the hunk header "TEXT". Add a section to your
848`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
849
850------------------------
851[diff "tex"]
852 xfuncname = "^(\\\\(sub)*section\\{.*)$"
853------------------------
854
855Note. A single level of backslashes are eaten by the
856configuration file parser, so you would need to double the
857backslashes; the pattern above picks a line that begins with a
858backslash, and zero or more occurrences of `sub` followed by
859`section` followed by open brace, to the end of line.
860
861There are a few built-in patterns to make this easier, and `tex`
862is one of them, so you do not have to write the above in your
863configuration file (you still need to enable this with the
864attribute mechanism, via `.gitattributes`). The following built in
865patterns are available:
866
867- `ada` suitable for source code in the Ada language.
868
869- `bash` suitable for source code in the Bourne-Again SHell language.
870 Covers a superset of POSIX shell function definitions.
871
872- `bibtex` suitable for files with BibTeX coded references.
873
874- `cpp` suitable for source code in the C and C++ languages.
875
876- `csharp` suitable for source code in the C# language.
877
878- `css` suitable for cascading style sheets.
879
880- `dts` suitable for devicetree (DTS) files.
881
882- `elixir` suitable for source code in the Elixir language.
883
884- `fortran` suitable for source code in the Fortran language.
885
886- `fountain` suitable for Fountain documents.
887
888- `golang` suitable for source code in the Go language.
889
890- `html` suitable for HTML/XHTML documents.
891
892- `java` suitable for source code in the Java language.
893
894- `kotlin` suitable for source code in the Kotlin language.
895
896- `markdown` suitable for Markdown documents.
897
898- `matlab` suitable for source code in the MATLAB and Octave languages.
899
900- `objc` suitable for source code in the Objective-C language.
901
902- `pascal` suitable for source code in the Pascal/Delphi language.
903
904- `perl` suitable for source code in the Perl language.
905
906- `php` suitable for source code in the PHP language.
907
908- `python` suitable for source code in the Python language.
909
910- `ruby` suitable for source code in the Ruby language.
911
912- `rust` suitable for source code in the Rust language.
913
914- `scheme` suitable for source code in the Scheme language.
915
916- `tex` suitable for source code for LaTeX documents.
917
918
919Customizing word diff
920^^^^^^^^^^^^^^^^^^^^^
921
922You can customize the rules that `git diff --word-diff` uses to
923split words in a line, by specifying an appropriate regular expression
924in the "diff.*.wordRegex" configuration variable. For example, in TeX
925a backslash followed by a sequence of letters forms a command, but
926several such commands can be run together without intervening
927whitespace. To separate them, use a regular expression in your
928`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
929
930------------------------
931[diff "tex"]
932 wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+"
933------------------------
934
935A built-in pattern is provided for all languages listed in the
936previous section.
937
938
939Performing text diffs of binary files
940^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
941
942Sometimes it is desirable to see the diff of a text-converted
943version of some binary files. For example, a word processor
944document can be converted to an ASCII text representation, and
945the diff of the text shown. Even though this conversion loses
946some information, the resulting diff is useful for human
947viewing (but cannot be applied directly).
948
949The `textconv` config option is used to define a program for
950performing such a conversion. The program should take a single
951argument, the name of a file to convert, and produce the
952resulting text on stdout.
953
954For example, to show the diff of the exif information of a
955file instead of the binary information (assuming you have the
956exif tool installed), add the following section to your
957`$GIT_DIR/config` file (or `$HOME/.gitconfig` file):
958
959------------------------
960[diff "jpg"]
961 textconv = exif
962------------------------
963
964NOTE: The text conversion is generally a one-way conversion;
965in this example, we lose the actual image contents and focus
966just on the text data. This means that diffs generated by
967textconv are _not_ suitable for applying. For this reason,
968only `git diff` and the `git log` family of commands (i.e.,
969log, whatchanged, show) will perform text conversion. `git
970format-patch` will never generate this output. If you want to
971send somebody a text-converted diff of a binary file (e.g.,
972because it quickly conveys the changes you have made), you
973should generate it separately and send it as a comment _in
974addition to_ the usual binary diff that you might send.
975
976Because text conversion can be slow, especially when doing a
977large number of them with `git log -p`, Git provides a mechanism
978to cache the output and use it in future diffs. To enable
979caching, set the "cachetextconv" variable in your diff driver's
980config. For example:
981
982------------------------
983[diff "jpg"]
984 textconv = exif
985 cachetextconv = true
986------------------------
987
988This will cache the result of running "exif" on each blob
989indefinitely. If you change the textconv config variable for a
990diff driver, Git will automatically invalidate the cache entries
991and re-run the textconv filter. If you want to invalidate the
992cache manually (e.g., because your version of "exif" was updated
993and now produces better output), you can remove the cache
994manually with `git update-ref -d refs/notes/textconv/jpg` (where
995"jpg" is the name of the diff driver, as in the example above).
996
997Choosing textconv versus external diff
998^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
999
1000If you want to show differences between binary or specially-formatted
1001blobs in your repository, you can choose to use either an external diff
1002command, or to use textconv to convert them to a diff-able text format.
1003Which method you choose depends on your exact situation.
1004
1005The advantage of using an external diff command is flexibility. You are
1006not bound to find line-oriented changes, nor is it necessary for the
1007output to resemble unified diff. You are free to locate and report
1008changes in the most appropriate way for your data format.
1009
1010A textconv, by comparison, is much more limiting. You provide a
1011transformation of the data into a line-oriented text format, and Git
1012uses its regular diff tools to generate the output. There are several
1013advantages to choosing this method:
1014
10151. Ease of use. It is often much simpler to write a binary to text
1016 transformation than it is to perform your own diff. In many cases,
1017 existing programs can be used as textconv filters (e.g., exif,
1018 odt2txt).
1019
10202. Git diff features. By performing only the transformation step
1021 yourself, you can still utilize many of Git's diff features,
1022 including colorization, word-diff, and combined diffs for merges.
1023
10243. Caching. Textconv caching can speed up repeated diffs, such as those
1025 you might trigger by running `git log -p`.
1026
1027
1028Marking files as binary
1029^^^^^^^^^^^^^^^^^^^^^^^
1030
1031Git usually guesses correctly whether a blob contains text or binary
1032data by examining the beginning of the contents. However, sometimes you
1033may want to override its decision, either because a blob contains binary
1034data later in the file, or because the content, while technically
1035composed of text characters, is opaque to a human reader. For example,
1036many postscript files contain only ASCII characters, but produce noisy
1037and meaningless diffs.
1038
1039The simplest way to mark a file as binary is to unset the diff
1040attribute in the `.gitattributes` file:
1041
1042------------------------
1043*.ps -diff
1044------------------------
1045
1046This will cause Git to generate `Binary files differ` (or a binary
1047patch, if binary patches are enabled) instead of a regular diff.
1048
1049However, one may also want to specify other diff driver attributes. For
1050example, you might want to use `textconv` to convert postscript files to
1051an ASCII representation for human viewing, but otherwise treat them as
1052binary files. You cannot specify both `-diff` and `diff=ps` attributes.
1053The solution is to use the `diff.*.binary` config option:
1054
1055------------------------
1056[diff "ps"]
1057 textconv = ps2ascii
1058 binary = true
1059------------------------
1060
1061Performing a three-way merge
1062~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1063
1064`merge`
1065^^^^^^^
1066
1067The attribute `merge` affects how three versions of a file are
1068merged when a file-level merge is necessary during `git merge`,
1069and other commands such as `git revert` and `git cherry-pick`.
1070
1071Set::
1072
1073 Built-in 3-way merge driver is used to merge the
1074 contents in a way similar to 'merge' command of `RCS`
1075 suite. This is suitable for ordinary text files.
1076
1077Unset::
1078
1079 Take the version from the current branch as the
1080 tentative merge result, and declare that the merge has
1081 conflicts. This is suitable for binary files that do
1082 not have a well-defined merge semantics.
1083
1084Unspecified::
1085
1086 By default, this uses the same built-in 3-way merge
1087 driver as is the case when the `merge` attribute is set.
1088 However, the `merge.default` configuration variable can name
1089 different merge driver to be used with paths for which the
1090 `merge` attribute is unspecified.
1091
1092String::
1093
1094 3-way merge is performed using the specified custom
1095 merge driver. The built-in 3-way merge driver can be
1096 explicitly specified by asking for "text" driver; the
1097 built-in "take the current branch" driver can be
1098 requested with "binary".
1099
1100
1101Built-in merge drivers
1102^^^^^^^^^^^^^^^^^^^^^^
1103
1104There are a few built-in low-level merge drivers defined that
1105can be asked for via the `merge` attribute.
1106
1107text::
1108
1109 Usual 3-way file level merge for text files. Conflicted
1110 regions are marked with conflict markers `<<<<<<<`,
1111 `=======` and `>>>>>>>`. The version from your branch
1112 appears before the `=======` marker, and the version
1113 from the merged branch appears after the `=======`
1114 marker.
1115
1116binary::
1117
1118 Keep the version from your branch in the work tree, but
1119 leave the path in the conflicted state for the user to
1120 sort out.
1121
1122union::
1123
1124 Run 3-way file level merge for text files, but take
1125 lines from both versions, instead of leaving conflict
1126 markers. This tends to leave the added lines in the
1127 resulting file in random order and the user should
1128 verify the result. Do not use this if you do not
1129 understand the implications.
1130
1131
1132Defining a custom merge driver
1133^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1134
1135The definition of a merge driver is done in the `.git/config`
1136file, not in the `gitattributes` file, so strictly speaking this
1137manual page is a wrong place to talk about it. However...
1138
1139To define a custom merge driver `filfre`, add a section to your
1140`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
1141
1142----------------------------------------------------------------
1143[merge "filfre"]
1144 name = feel-free merge driver
1145 driver = filfre %O %A %B %L %P
1146 recursive = binary
1147----------------------------------------------------------------
1148
1149The `merge.*.name` variable gives the driver a human-readable
1150name.
1151
1152The `merge.*.driver` variable's value is used to construct a
1153command to run to common ancestor's version (`%O`), current
1154version (`%A`) and the other branches' version (`%B`). These
1155three tokens are replaced with the names of temporary files that
1156hold the contents of these versions when the command line is
1157built. Additionally, `%L` will be replaced with the conflict marker
1158size (see below).
1159
1160The merge driver is expected to leave the result of the merge in
1161the file named with `%A` by overwriting it, and exit with zero
1162status if it managed to merge them cleanly, or non-zero if there
1163were conflicts. When the driver crashes (e.g. killed by SEGV),
1164it is expected to exit with non-zero status that are higher than
1165128, and in such a case, the merge results in a failure (which is
1166different from producing a conflict).
1167
1168The `merge.*.recursive` variable specifies what other merge
1169driver to use when the merge driver is called for an internal
1170merge between common ancestors, when there are more than one.
1171When left unspecified, the driver itself is used for both
1172internal merge and the final merge.
1173
1174The merge driver can learn the pathname in which the merged result
1175will be stored via placeholder `%P`. The conflict labels to be used
1176for the common ancestor, local head and other head can be passed by
1177using `%S`, `%X` and `%Y` respectively.
1178
1179`conflict-marker-size`
1180^^^^^^^^^^^^^^^^^^^^^^
1181
1182This attribute controls the length of conflict markers left in
1183the work tree file during a conflicted merge. Only a positive
1184integer has a meaningful effect.
1185
1186For example, this line in `.gitattributes` can be used to tell the merge
1187machinery to leave much longer (instead of the usual 7-character-long)
1188conflict markers when merging the file `Documentation/git-merge.adoc`
1189results in a conflict.
1190
1191------------------------
1192Documentation/git-merge.adoc conflict-marker-size=32
1193------------------------
1194
1195
1196Checking whitespace errors
1197~~~~~~~~~~~~~~~~~~~~~~~~~~
1198
1199`whitespace`
1200^^^^^^^^^^^^
1201
1202The `core.whitespace` configuration variable allows you to define what
1203'diff' and 'apply' should consider whitespace errors for all paths in
1204the project (See linkgit:git-config[1]). This attribute gives you finer
1205control per path.
1206
1207Set::
1208
1209 Notice all types of potential whitespace errors known to Git.
1210 The tab width is taken from the value of the `core.whitespace`
1211 configuration variable.
1212
1213Unset::
1214
1215 Do not notice anything as error.
1216
1217Unspecified::
1218
1219 Use the value of the `core.whitespace` configuration variable to
1220 decide what to notice as error.
1221
1222String::
1223
1224 Specify a comma separated list of common whitespace problems to
1225 notice in the same format as the `core.whitespace` configuration
1226 variable.
1227
1228
1229Creating an archive
1230~~~~~~~~~~~~~~~~~~~
1231
1232`export-ignore`
1233^^^^^^^^^^^^^^^
1234
1235Files and directories with the attribute `export-ignore` won't be added to
1236archive files.
1237
1238`export-subst`
1239^^^^^^^^^^^^^^
1240
1241If the attribute `export-subst` is set for a file then Git will expand
1242several placeholders when adding this file to an archive. The
1243expansion depends on the availability of a commit ID, i.e., if
1244linkgit:git-archive[1] has been given a tree instead of a commit or a
1245tag then no replacement will be done. The placeholders are the same
1246as those for the option `--pretty=format:` of linkgit:git-log[1],
1247except that they need to be wrapped like this: `$Format:PLACEHOLDERS$`
1248in the file. E.g. the string `$Format:%H$` will be replaced by the
1249commit hash. However, only one `%(describe)` placeholder is expanded
1250per archive to avoid denial-of-service attacks.
1251
1252
1253Packing objects
1254~~~~~~~~~~~~~~~
1255
1256`delta`
1257^^^^^^^
1258
1259Delta compression will not be attempted for blobs for paths with the
1260attribute `delta` set to false.
1261
1262
1263Viewing files in GUI tools
1264~~~~~~~~~~~~~~~~~~~~~~~~~~
1265
1266`encoding`
1267^^^^^^^^^^
1268
1269The value of this attribute specifies the character encoding that should
1270be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to
1271display the contents of the relevant file. Note that due to performance
1272considerations linkgit:gitk[1] does not use this attribute unless you
1273manually enable per-file encodings in its options.
1274
1275If this attribute is not set or has an invalid value, the value of the
1276`gui.encoding` configuration variable is used instead
1277(See linkgit:git-config[1]).
1278
1279
1280USING MACRO ATTRIBUTES
1281----------------------
1282
1283You do not want any end-of-line conversions applied to, nor textual diffs
1284produced for, any binary file you track. You would need to specify e.g.
1285
1286------------
1287*.jpg -text -diff
1288------------
1289
1290but that may become cumbersome, when you have many attributes. Using
1291macro attributes, you can define an attribute that, when set, also
1292sets or unsets a number of other attributes at the same time. The
1293system knows a built-in macro attribute, `binary`:
1294
1295------------
1296*.jpg binary
1297------------
1298
1299Setting the "binary" attribute also unsets the "text" and "diff"
1300attributes as above. Note that macro attributes can only be "Set",
1301though setting one might have the effect of setting or unsetting other
1302attributes or even returning other attributes to the "Unspecified"
1303state.
1304
1305
1306DEFINING MACRO ATTRIBUTES
1307-------------------------
1308
1309Custom macro attributes can be defined only in top-level gitattributes
1310files (`$GIT_DIR/info/attributes`, the `.gitattributes` file at the
1311top level of the working tree, or the global or system-wide
1312gitattributes files), not in `.gitattributes` files in working tree
1313subdirectories. The built-in macro attribute "binary" is equivalent
1314to:
1315
1316------------
1317[attr]binary -diff -merge -text
1318------------
1319
1320NOTES
1321-----
1322
1323Git does not follow symbolic links when accessing a `.gitattributes`
1324file in the working tree. This keeps behavior consistent when the file
1325is accessed from the index or a tree versus from the filesystem.
1326
1327EXAMPLES
1328--------
1329
1330If you have these three `gitattributes` file:
1331
1332----------------------------------------------------------------
1333(in $GIT_DIR/info/attributes)
1334
1335a* foo !bar -baz
1336
1337(in .gitattributes)
1338abc foo bar baz
1339
1340(in t/.gitattributes)
1341ab* merge=filfre
1342abc -foo -bar
1343*.c frotz
1344----------------------------------------------------------------
1345
1346the attributes given to path `t/abc` are computed as follows:
1347
13481. By examining `t/.gitattributes` (which is in the same
1349 directory as the path in question), Git finds that the first
1350 line matches. `merge` attribute is set. It also finds that
1351 the second line matches, and attributes `foo` and `bar`
1352 are unset.
1353
13542. Then it examines `.gitattributes` (which is in the parent
1355 directory), and finds that the first line matches, but
1356 `t/.gitattributes` file already decided how `merge`, `foo`
1357 and `bar` attributes should be given to this path, so it
1358 leaves `foo` and `bar` unset. Attribute `baz` is set.
1359
13603. Finally it examines `$GIT_DIR/info/attributes`. This file
1361 is used to override the in-tree settings. The first line is
1362 a match, and `foo` is set, `bar` is reverted to unspecified
1363 state, and `baz` is unset.
1364
1365As the result, the attributes assignment to `t/abc` becomes:
1366
1367----------------------------------------------------------------
1368foo set to true
1369bar unspecified
1370baz set to false
1371merge set to string value "filfre"
1372frotz unspecified
1373----------------------------------------------------------------
1374
1375
1376SEE ALSO
1377--------
1378linkgit:git-check-attr[1].
1379
1380GIT
1381---
1382Part of the linkgit:git[1] suite