Documentation / gitattributes.txton commit Allow checkout -B <current-branch> to update the current branch (39bd6f7)
   1gitattributes(5)
   2================
   3
   4NAME
   5----
   6gitattributes - defining attributes per path
   7
   8SYNOPSIS
   9--------
  10$GIT_DIR/info/attributes, .gitattributes
  11
  12
  13DESCRIPTION
  14-----------
  15
  16A `gitattributes` file is a simple text file that gives
  17`attributes` to pathnames.
  18
  19Each line in `gitattributes` file is of form:
  20
  21        pattern attr1 attr2 ...
  22
  23That is, a pattern followed by an attributes list,
  24separated by whitespaces.  When the pattern matches the
  25path in question, the attributes listed on the line are given to
  26the path.
  27
  28Each attribute can be in one of these states for a given path:
  29
  30Set::
  31
  32        The path has the attribute with special value "true";
  33        this is specified by listing only the name of the
  34        attribute in the attribute list.
  35
  36Unset::
  37
  38        The path has the attribute with special value "false";
  39        this is specified by listing the name of the attribute
  40        prefixed with a dash `-` in the attribute list.
  41
  42Set to a value::
  43
  44        The path has the attribute with specified string value;
  45        this is specified by listing the name of the attribute
  46        followed by an equal sign `=` and its value in the
  47        attribute list.
  48
  49Unspecified::
  50
  51        No pattern matches the path, and nothing says if
  52        the path has or does not have the attribute, the
  53        attribute for the path is said to be Unspecified.
  54
  55When more than one pattern matches the path, a later line
  56overrides an earlier line.  This overriding is done per
  57attribute.  The rules how the pattern matches paths are the
  58same as in `.gitignore` files; see linkgit:gitignore[5].
  59
  60When deciding what attributes are assigned to a path, git
  61consults `$GIT_DIR/info/attributes` file (which has the highest
  62precedence), `.gitattributes` file in the same directory as the
  63path in question, and its parent directories up to the toplevel of the
  64work tree (the further the directory that contains `.gitattributes`
  65is from the path in question, the lower its precedence). Finally
  66global and system-wide files are considered (they have the lowest
  67precedence).
  68
  69If you wish to affect only a single repository (i.e., to assign
  70attributes to files that are particular to
  71one user's workflow for that repository), then
  72attributes should be placed in the `$GIT_DIR/info/attributes` file.
  73Attributes which should be version-controlled and distributed to other
  74repositories (i.e., attributes of interest to all users) should go into
  75`.gitattributes` files. Attributes that should affect all repositories
  76for a single user should be placed in a file specified by the
  77`core.attributesfile` configuration option (see linkgit:git-config[1]).
  78Attributes for all users on a system should be placed in the
  79`$(prefix)/etc/gitattributes` file.
  80
  81Sometimes you would need to override an setting of an attribute
  82for a path to `Unspecified` state.  This can be done by listing
  83the name of the attribute prefixed with an exclamation point `!`.
  84
  85
  86EFFECTS
  87-------
  88
  89Certain operations by git can be influenced by assigning
  90particular attributes to a path.  Currently, the following
  91operations are attributes-aware.
  92
  93Checking-out and checking-in
  94~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  95
  96These attributes affect how the contents stored in the
  97repository are copied to the working tree files when commands
  98such as 'git checkout' and 'git merge' run.  They also affect how
  99git stores the contents you prepare in the working tree in the
 100repository upon 'git add' and 'git commit'.
 101
 102`text`
 103^^^^^^
 104
 105This attribute enables and controls end-of-line normalization.  When a
 106text file is normalized, its line endings are converted to LF in the
 107repository.  To control what line ending style is used in the working
 108directory, use the `eol` attribute for a single file and the
 109`core.eol` configuration variable for all text files.
 110
 111Set::
 112
 113        Setting the `text` attribute on a path enables end-of-line
 114        normalization and marks the path as a text file.  End-of-line
 115        conversion takes place without guessing the content type.
 116
 117Unset::
 118
 119        Unsetting the `text` attribute on a path tells git not to
 120        attempt any end-of-line conversion upon checkin or checkout.
 121
 122Set to string value "auto"::
 123
 124        When `text` is set to "auto", the path is marked for automatic
 125        end-of-line normalization.  If git decides that the content is
 126        text, its line endings are normalized to LF on checkin.
 127
 128Unspecified::
 129
 130        If the `text` attribute is unspecified, git uses the
 131        `core.autocrlf` configuration variable to determine if the
 132        file should be converted.
 133
 134Any other value causes git to act as if `text` has been left
 135unspecified.
 136
 137`eol`
 138^^^^^
 139
 140This attribute sets a specific line-ending style to be used in the
 141working directory.  It enables end-of-line normalization without any
 142content checks, effectively setting the `text` attribute.
 143
 144Set to string value "crlf"::
 145
 146        This setting forces git to normalize line endings for this
 147        file on checkin and convert them to CRLF when the file is
 148        checked out.
 149
 150Set to string value "lf"::
 151
 152        This setting forces git to normalize line endings to LF on
 153        checkin and prevents conversion to CRLF when the file is
 154        checked out.
 155
 156Backwards compatibility with `crlf` attribute
 157^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 158
 159For backwards compatibility, the `crlf` attribute is interpreted as
 160follows:
 161
 162------------------------
 163crlf            text
 164-crlf           -text
 165crlf=input      eol=lf
 166------------------------
 167
 168End-of-line conversion
 169^^^^^^^^^^^^^^^^^^^^^^
 170
 171While git normally leaves file contents alone, it can be configured to
 172normalize line endings to LF in the repository and, optionally, to
 173convert them to CRLF when files are checked out.
 174
 175Here is an example that will make git normalize .txt, .vcproj and .sh
 176files, ensure that .vcproj files have CRLF and .sh files have LF in
 177the working directory, and prevent .jpg files from being normalized
 178regardless of their content.
 179
 180------------------------
 181*.txt           text
 182*.vcproj        eol=crlf
 183*.sh            eol=lf
 184*.jpg           -text
 185------------------------
 186
 187Other source code management systems normalize all text files in their
 188repositories, and there are two ways to enable similar automatic
 189normalization in git.
 190
 191If you simply want to have CRLF line endings in your working directory
 192regardless of the repository you are working with, you can set the
 193config variable "core.autocrlf" without changing any attributes.
 194
 195------------------------
 196[core]
 197        autocrlf = true
 198------------------------
 199
 200This does not force normalization of all text files, but does ensure
 201that text files that you introduce to the repository have their line
 202endings normalized to LF when they are added, and that files that are
 203already normalized in the repository stay normalized.
 204
 205If you want to interoperate with a source code management system that
 206enforces end-of-line normalization, or you simply want all text files
 207in your repository to be normalized, you should instead set the `text`
 208attribute to "auto" for _all_ files.
 209
 210------------------------
 211*       text=auto
 212------------------------
 213
 214This ensures that all files that git considers to be text will have
 215normalized (LF) line endings in the repository.  The `core.eol`
 216configuration variable controls which line endings git will use for
 217normalized files in your working directory; the default is to use the
 218native line ending for your platform, or CRLF if `core.autocrlf` is
 219set.
 220
 221NOTE: When `text=auto` normalization is enabled in an existing
 222repository, any text files containing CRLFs should be normalized.  If
 223they are not they will be normalized the next time someone tries to
 224change them, causing unfortunate misattribution.  From a clean working
 225directory:
 226
 227-------------------------------------------------
 228$ echo "* text=auto" >>.gitattributes
 229$ rm .git/index     # Remove the index to force git to
 230$ git reset         # re-scan the working directory
 231$ git status        # Show files that will be normalized
 232$ git add -u
 233$ git add .gitattributes
 234$ git commit -m "Introduce end-of-line normalization"
 235-------------------------------------------------
 236
 237If any files that should not be normalized show up in 'git status',
 238unset their `text` attribute before running 'git add -u'.
 239
 240------------------------
 241manual.pdf      -text
 242------------------------
 243
 244Conversely, text files that git does not detect can have normalization
 245enabled manually.
 246
 247------------------------
 248weirdchars.txt  text
 249------------------------
 250
 251If `core.safecrlf` is set to "true" or "warn", git verifies if
 252the conversion is reversible for the current setting of
 253`core.autocrlf`.  For "true", git rejects irreversible
 254conversions; for "warn", git only prints a warning but accepts
 255an irreversible conversion.  The safety triggers to prevent such
 256a conversion done to the files in the work tree, but there are a
 257few exceptions.  Even though...
 258
 259- 'git add' itself does not touch the files in the work tree, the
 260  next checkout would, so the safety triggers;
 261
 262- 'git apply' to update a text file with a patch does touch the files
 263  in the work tree, but the operation is about text files and CRLF
 264  conversion is about fixing the line ending inconsistencies, so the
 265  safety does not trigger;
 266
 267- 'git diff' itself does not touch the files in the work tree, it is
 268  often run to inspect the changes you intend to next 'git add'.  To
 269  catch potential problems early, safety triggers.
 270
 271
 272`ident`
 273^^^^^^^
 274
 275When the attribute `ident` is set for a path, git replaces
 276`$Id$` in the blob object with `$Id:`, followed by the
 27740-character hexadecimal blob object name, followed by a dollar
 278sign `$` upon checkout.  Any byte sequence that begins with
 279`$Id:` and ends with `$` in the worktree file is replaced
 280with `$Id$` upon check-in.
 281
 282
 283`filter`
 284^^^^^^^^
 285
 286A `filter` attribute can be set to a string value that names a
 287filter driver specified in the configuration.
 288
 289A filter driver consists of a `clean` command and a `smudge`
 290command, either of which can be left unspecified.  Upon
 291checkout, when the `smudge` command is specified, the command is
 292fed the blob object from its standard input, and its standard
 293output is used to update the worktree file.  Similarly, the
 294`clean` command is used to convert the contents of worktree file
 295upon checkin.
 296
 297A missing filter driver definition in the config is not an error
 298but makes the filter a no-op passthru.
 299
 300The content filtering is done to massage the content into a
 301shape that is more convenient for the platform, filesystem, and
 302the user to use.  The key phrase here is "more convenient" and not
 303"turning something unusable into usable".  In other words, the
 304intent is that if someone unsets the filter driver definition,
 305or does not have the appropriate filter program, the project
 306should still be usable.
 307
 308For example, in .gitattributes, you would assign the `filter`
 309attribute for paths.
 310
 311------------------------
 312*.c     filter=indent
 313------------------------
 314
 315Then you would define a "filter.indent.clean" and "filter.indent.smudge"
 316configuration in your .git/config to specify a pair of commands to
 317modify the contents of C programs when the source files are checked
 318in ("clean" is run) and checked out (no change is made because the
 319command is "cat").
 320
 321------------------------
 322[filter "indent"]
 323        clean = indent
 324        smudge = cat
 325------------------------
 326
 327For best results, `clean` should not alter its output further if it is
 328run twice ("clean->clean" should be equivalent to "clean"), and
 329multiple `smudge` commands should not alter `clean`'s output
 330("smudge->smudge->clean" should be equivalent to "clean").  See the
 331section on merging below.
 332
 333The "indent" filter is well-behaved in this regard: it will not modify
 334input that is already correctly indented.  In this case, the lack of a
 335smudge filter means that the clean filter _must_ accept its own output
 336without modifying it.
 337
 338Sequence "%f" on the filter command line is replaced with the name of
 339the file the filter is working on.  A filter might use this in keyword
 340substitution.  For example:
 341
 342------------------------
 343[filter "p4"]
 344        clean = git-p4-filter --clean %f
 345        smudge = git-p4-filter --smudge %f
 346------------------------
 347
 348
 349Interaction between checkin/checkout attributes
 350^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 351
 352In the check-in codepath, the worktree file is first converted
 353with `filter` driver (if specified and corresponding driver
 354defined), then the result is processed with `ident` (if
 355specified), and then finally with `text` (again, if specified
 356and applicable).
 357
 358In the check-out codepath, the blob content is first converted
 359with `text`, and then `ident` and fed to `filter`.
 360
 361
 362Merging branches with differing checkin/checkout attributes
 363^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 364
 365If you have added attributes to a file that cause the canonical
 366repository format for that file to change, such as adding a
 367clean/smudge filter or text/eol/ident attributes, merging anything
 368where the attribute is not in place would normally cause merge
 369conflicts.
 370
 371To prevent these unnecessary merge conflicts, git can be told to run a
 372virtual check-out and check-in of all three stages of a file when
 373resolving a three-way merge by setting the `merge.renormalize`
 374configuration variable.  This prevents changes caused by check-in
 375conversion from causing spurious merge conflicts when a converted file
 376is merged with an unconverted file.
 377
 378As long as a "smudge->clean" results in the same output as a "clean"
 379even on files that are already smudged, this strategy will
 380automatically resolve all filter-related conflicts.  Filters that do
 381not act in this way may cause additional merge conflicts that must be
 382resolved manually.
 383
 384
 385Generating diff text
 386~~~~~~~~~~~~~~~~~~~~
 387
 388`diff`
 389^^^^^^
 390
 391The attribute `diff` affects how 'git' generates diffs for particular
 392files. It can tell git whether to generate a textual patch for the path
 393or to treat the path as a binary file.  It can also affect what line is
 394shown on the hunk header `@@ -k,l +n,m @@` line, tell git to use an
 395external command to generate the diff, or ask git to convert binary
 396files to a text format before generating the diff.
 397
 398Set::
 399
 400        A path to which the `diff` attribute is set is treated
 401        as text, even when they contain byte values that
 402        normally never appear in text files, such as NUL.
 403
 404Unset::
 405
 406        A path to which the `diff` attribute is unset will
 407        generate `Binary files differ` (or a binary patch, if
 408        binary patches are enabled).
 409
 410Unspecified::
 411
 412        A path to which the `diff` attribute is unspecified
 413        first gets its contents inspected, and if it looks like
 414        text, it is treated as text.  Otherwise it would
 415        generate `Binary files differ`.
 416
 417String::
 418
 419        Diff is shown using the specified diff driver.  Each driver may
 420        specify one or more options, as described in the following
 421        section. The options for the diff driver "foo" are defined
 422        by the configuration variables in the "diff.foo" section of the
 423        git config file.
 424
 425
 426Defining an external diff driver
 427^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 428
 429The definition of a diff driver is done in `gitconfig`, not
 430`gitattributes` file, so strictly speaking this manual page is a
 431wrong place to talk about it.  However...
 432
 433To define an external diff driver `jcdiff`, add a section to your
 434`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 435
 436----------------------------------------------------------------
 437[diff "jcdiff"]
 438        command = j-c-diff
 439----------------------------------------------------------------
 440
 441When git needs to show you a diff for the path with `diff`
 442attribute set to `jcdiff`, it calls the command you specified
 443with the above configuration, i.e. `j-c-diff`, with 7
 444parameters, just like `GIT_EXTERNAL_DIFF` program is called.
 445See linkgit:git[1] for details.
 446
 447
 448Defining a custom hunk-header
 449^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 450
 451Each group of changes (called a "hunk") in the textual diff output
 452is prefixed with a line of the form:
 453
 454        @@ -k,l +n,m @@ TEXT
 455
 456This is called a 'hunk header'.  The "TEXT" portion is by default a line
 457that begins with an alphabet, an underscore or a dollar sign; this
 458matches what GNU 'diff -p' output uses.  This default selection however
 459is not suited for some contents, and you can use a customized pattern
 460to make a selection.
 461
 462First, in .gitattributes, you would assign the `diff` attribute
 463for paths.
 464
 465------------------------
 466*.tex   diff=tex
 467------------------------
 468
 469Then, you would define a "diff.tex.xfuncname" configuration to
 470specify a regular expression that matches a line that you would
 471want to appear as the hunk header "TEXT". Add a section to your
 472`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 473
 474------------------------
 475[diff "tex"]
 476        xfuncname = "^(\\\\(sub)*section\\{.*)$"
 477------------------------
 478
 479Note.  A single level of backslashes are eaten by the
 480configuration file parser, so you would need to double the
 481backslashes; the pattern above picks a line that begins with a
 482backslash, and zero or more occurrences of `sub` followed by
 483`section` followed by open brace, to the end of line.
 484
 485There are a few built-in patterns to make this easier, and `tex`
 486is one of them, so you do not have to write the above in your
 487configuration file (you still need to enable this with the
 488attribute mechanism, via `.gitattributes`).  The following built in
 489patterns are available:
 490
 491- `bibtex` suitable for files with BibTeX coded references.
 492
 493- `cpp` suitable for source code in the C and C++ languages.
 494
 495- `csharp` suitable for source code in the C# language.
 496
 497- `fortran` suitable for source code in the Fortran language.
 498
 499- `html` suitable for HTML/XHTML documents.
 500
 501- `java` suitable for source code in the Java language.
 502
 503- `objc` suitable for source code in the Objective-C language.
 504
 505- `pascal` suitable for source code in the Pascal/Delphi language.
 506
 507- `perl` suitable for source code in the Perl language.
 508
 509- `php` suitable for source code in the PHP language.
 510
 511- `python` suitable for source code in the Python language.
 512
 513- `ruby` suitable for source code in the Ruby language.
 514
 515- `tex` suitable for source code for LaTeX documents.
 516
 517
 518Customizing word diff
 519^^^^^^^^^^^^^^^^^^^^^
 520
 521You can customize the rules that `git diff --word-diff` uses to
 522split words in a line, by specifying an appropriate regular expression
 523in the "diff.*.wordRegex" configuration variable.  For example, in TeX
 524a backslash followed by a sequence of letters forms a command, but
 525several such commands can be run together without intervening
 526whitespace.  To separate them, use a regular expression in your
 527`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 528
 529------------------------
 530[diff "tex"]
 531        wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+"
 532------------------------
 533
 534A built-in pattern is provided for all languages listed in the
 535previous section.
 536
 537
 538Performing text diffs of binary files
 539^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 540
 541Sometimes it is desirable to see the diff of a text-converted
 542version of some binary files. For example, a word processor
 543document can be converted to an ASCII text representation, and
 544the diff of the text shown. Even though this conversion loses
 545some information, the resulting diff is useful for human
 546viewing (but cannot be applied directly).
 547
 548The `textconv` config option is used to define a program for
 549performing such a conversion. The program should take a single
 550argument, the name of a file to convert, and produce the
 551resulting text on stdout.
 552
 553For example, to show the diff of the exif information of a
 554file instead of the binary information (assuming you have the
 555exif tool installed), add the following section to your
 556`$GIT_DIR/config` file (or `$HOME/.gitconfig` file):
 557
 558------------------------
 559[diff "jpg"]
 560        textconv = exif
 561------------------------
 562
 563NOTE: The text conversion is generally a one-way conversion;
 564in this example, we lose the actual image contents and focus
 565just on the text data. This means that diffs generated by
 566textconv are _not_ suitable for applying. For this reason,
 567only `git diff` and the `git log` family of commands (i.e.,
 568log, whatchanged, show) will perform text conversion. `git
 569format-patch` will never generate this output. If you want to
 570send somebody a text-converted diff of a binary file (e.g.,
 571because it quickly conveys the changes you have made), you
 572should generate it separately and send it as a comment _in
 573addition to_ the usual binary diff that you might send.
 574
 575Because text conversion can be slow, especially when doing a
 576large number of them with `git log -p`, git provides a mechanism
 577to cache the output and use it in future diffs.  To enable
 578caching, set the "cachetextconv" variable in your diff driver's
 579config. For example:
 580
 581------------------------
 582[diff "jpg"]
 583        textconv = exif
 584        cachetextconv = true
 585------------------------
 586
 587This will cache the result of running "exif" on each blob
 588indefinitely. If you change the textconv config variable for a
 589diff driver, git will automatically invalidate the cache entries
 590and re-run the textconv filter. If you want to invalidate the
 591cache manually (e.g., because your version of "exif" was updated
 592and now produces better output), you can remove the cache
 593manually with `git update-ref -d refs/notes/textconv/jpg` (where
 594"jpg" is the name of the diff driver, as in the example above).
 595
 596Choosing textconv versus external diff
 597^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 598
 599If you want to show differences between binary or specially-formatted
 600blobs in your repository, you can choose to use either an external diff
 601command, or to use textconv to convert them to a diff-able text format.
 602Which method you choose depends on your exact situation.
 603
 604The advantage of using an external diff command is flexibility. You are
 605not bound to find line-oriented changes, nor is it necessary for the
 606output to resemble unified diff. You are free to locate and report
 607changes in the most appropriate way for your data format.
 608
 609A textconv, by comparison, is much more limiting. You provide a
 610transformation of the data into a line-oriented text format, and git
 611uses its regular diff tools to generate the output. There are several
 612advantages to choosing this method:
 613
 6141. Ease of use. It is often much simpler to write a binary to text
 615   transformation than it is to perform your own diff. In many cases,
 616   existing programs can be used as textconv filters (e.g., exif,
 617   odt2txt).
 618
 6192. Git diff features. By performing only the transformation step
 620   yourself, you can still utilize many of git's diff features,
 621   including colorization, word-diff, and combined diffs for merges.
 622
 6233. Caching. Textconv caching can speed up repeated diffs, such as those
 624   you might trigger by running `git log -p`.
 625
 626
 627Marking files as binary
 628^^^^^^^^^^^^^^^^^^^^^^^
 629
 630Git usually guesses correctly whether a blob contains text or binary
 631data by examining the beginning of the contents. However, sometimes you
 632may want to override its decision, either because a blob contains binary
 633data later in the file, or because the content, while technically
 634composed of text characters, is opaque to a human reader. For example,
 635many postscript files contain only ascii characters, but produce noisy
 636and meaningless diffs.
 637
 638The simplest way to mark a file as binary is to unset the diff
 639attribute in the `.gitattributes` file:
 640
 641------------------------
 642*.ps -diff
 643------------------------
 644
 645This will cause git to generate `Binary files differ` (or a binary
 646patch, if binary patches are enabled) instead of a regular diff.
 647
 648However, one may also want to specify other diff driver attributes. For
 649example, you might want to use `textconv` to convert postscript files to
 650an ascii representation for human viewing, but otherwise treat them as
 651binary files. You cannot specify both `-diff` and `diff=ps` attributes.
 652The solution is to use the `diff.*.binary` config option:
 653
 654------------------------
 655[diff "ps"]
 656  textconv = ps2ascii
 657  binary = true
 658------------------------
 659
 660Performing a three-way merge
 661~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 662
 663`merge`
 664^^^^^^^
 665
 666The attribute `merge` affects how three versions of a file are
 667merged when a file-level merge is necessary during `git merge`,
 668and other commands such as `git revert` and `git cherry-pick`.
 669
 670Set::
 671
 672        Built-in 3-way merge driver is used to merge the
 673        contents in a way similar to 'merge' command of `RCS`
 674        suite.  This is suitable for ordinary text files.
 675
 676Unset::
 677
 678        Take the version from the current branch as the
 679        tentative merge result, and declare that the merge has
 680        conflicts.  This is suitable for binary files that do
 681        not have a well-defined merge semantics.
 682
 683Unspecified::
 684
 685        By default, this uses the same built-in 3-way merge
 686        driver as is the case when the `merge` attribute is set.
 687        However, the `merge.default` configuration variable can name
 688        different merge driver to be used with paths for which the
 689        `merge` attribute is unspecified.
 690
 691String::
 692
 693        3-way merge is performed using the specified custom
 694        merge driver.  The built-in 3-way merge driver can be
 695        explicitly specified by asking for "text" driver; the
 696        built-in "take the current branch" driver can be
 697        requested with "binary".
 698
 699
 700Built-in merge drivers
 701^^^^^^^^^^^^^^^^^^^^^^
 702
 703There are a few built-in low-level merge drivers defined that
 704can be asked for via the `merge` attribute.
 705
 706text::
 707
 708        Usual 3-way file level merge for text files.  Conflicted
 709        regions are marked with conflict markers `<<<<<<<`,
 710        `=======` and `>>>>>>>`.  The version from your branch
 711        appears before the `=======` marker, and the version
 712        from the merged branch appears after the `=======`
 713        marker.
 714
 715binary::
 716
 717        Keep the version from your branch in the work tree, but
 718        leave the path in the conflicted state for the user to
 719        sort out.
 720
 721union::
 722
 723        Run 3-way file level merge for text files, but take
 724        lines from both versions, instead of leaving conflict
 725        markers.  This tends to leave the added lines in the
 726        resulting file in random order and the user should
 727        verify the result. Do not use this if you do not
 728        understand the implications.
 729
 730
 731Defining a custom merge driver
 732^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 733
 734The definition of a merge driver is done in the `.git/config`
 735file, not in the `gitattributes` file, so strictly speaking this
 736manual page is a wrong place to talk about it.  However...
 737
 738To define a custom merge driver `filfre`, add a section to your
 739`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 740
 741----------------------------------------------------------------
 742[merge "filfre"]
 743        name = feel-free merge driver
 744        driver = filfre %O %A %B
 745        recursive = binary
 746----------------------------------------------------------------
 747
 748The `merge.*.name` variable gives the driver a human-readable
 749name.
 750
 751The `merge.*.driver` variable's value is used to construct a
 752command to run to merge ancestor's version (`%O`), current
 753version (`%A`) and the other branches' version (`%B`).  These
 754three tokens are replaced with the names of temporary files that
 755hold the contents of these versions when the command line is
 756built. Additionally, %L will be replaced with the conflict marker
 757size (see below).
 758
 759The merge driver is expected to leave the result of the merge in
 760the file named with `%A` by overwriting it, and exit with zero
 761status if it managed to merge them cleanly, or non-zero if there
 762were conflicts.
 763
 764The `merge.*.recursive` variable specifies what other merge
 765driver to use when the merge driver is called for an internal
 766merge between common ancestors, when there are more than one.
 767When left unspecified, the driver itself is used for both
 768internal merge and the final merge.
 769
 770
 771`conflict-marker-size`
 772^^^^^^^^^^^^^^^^^^^^^^
 773
 774This attribute controls the length of conflict markers left in
 775the work tree file during a conflicted merge.  Only setting to
 776the value to a positive integer has any meaningful effect.
 777
 778For example, this line in `.gitattributes` can be used to tell the merge
 779machinery to leave much longer (instead of the usual 7-character-long)
 780conflict markers when merging the file `Documentation/git-merge.txt`
 781results in a conflict.
 782
 783------------------------
 784Documentation/git-merge.txt     conflict-marker-size=32
 785------------------------
 786
 787
 788Checking whitespace errors
 789~~~~~~~~~~~~~~~~~~~~~~~~~~
 790
 791`whitespace`
 792^^^^^^^^^^^^
 793
 794The `core.whitespace` configuration variable allows you to define what
 795'diff' and 'apply' should consider whitespace errors for all paths in
 796the project (See linkgit:git-config[1]).  This attribute gives you finer
 797control per path.
 798
 799Set::
 800
 801        Notice all types of potential whitespace errors known to git.
 802        The tab width is taken from the value of the `core.whitespace`
 803        configuration variable.
 804
 805Unset::
 806
 807        Do not notice anything as error.
 808
 809Unspecified::
 810
 811        Use the value of the `core.whitespace` configuration variable to
 812        decide what to notice as error.
 813
 814String::
 815
 816        Specify a comma separate list of common whitespace problems to
 817        notice in the same format as the `core.whitespace` configuration
 818        variable.
 819
 820
 821Creating an archive
 822~~~~~~~~~~~~~~~~~~~
 823
 824`export-ignore`
 825^^^^^^^^^^^^^^^
 826
 827Files and directories with the attribute `export-ignore` won't be added to
 828archive files.
 829
 830`export-subst`
 831^^^^^^^^^^^^^^
 832
 833If the attribute `export-subst` is set for a file then git will expand
 834several placeholders when adding this file to an archive.  The
 835expansion depends on the availability of a commit ID, i.e., if
 836linkgit:git-archive[1] has been given a tree instead of a commit or a
 837tag then no replacement will be done.  The placeholders are the same
 838as those for the option `--pretty=format:` of linkgit:git-log[1],
 839except that they need to be wrapped like this: `$Format:PLACEHOLDERS$`
 840in the file.  E.g. the string `$Format:%H$` will be replaced by the
 841commit hash.
 842
 843
 844Packing objects
 845~~~~~~~~~~~~~~~
 846
 847`delta`
 848^^^^^^^
 849
 850Delta compression will not be attempted for blobs for paths with the
 851attribute `delta` set to false.
 852
 853
 854Viewing files in GUI tools
 855~~~~~~~~~~~~~~~~~~~~~~~~~~
 856
 857`encoding`
 858^^^^^^^^^^
 859
 860The value of this attribute specifies the character encoding that should
 861be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to
 862display the contents of the relevant file. Note that due to performance
 863considerations linkgit:gitk[1] does not use this attribute unless you
 864manually enable per-file encodings in its options.
 865
 866If this attribute is not set or has an invalid value, the value of the
 867`gui.encoding` configuration variable is used instead
 868(See linkgit:git-config[1]).
 869
 870
 871USING MACRO ATTRIBUTES
 872----------------------
 873
 874You do not want any end-of-line conversions applied to, nor textual diffs
 875produced for, any binary file you track.  You would need to specify e.g.
 876
 877------------
 878*.jpg -text -diff
 879------------
 880
 881but that may become cumbersome, when you have many attributes.  Using
 882macro attributes, you can define an attribute that, when set, also
 883sets or unsets a number of other attributes at the same time.  The
 884system knows a built-in macro attribute, `binary`:
 885
 886------------
 887*.jpg binary
 888------------
 889
 890Setting the "binary" attribute also unsets the "text" and "diff"
 891attributes as above.  Note that macro attributes can only be "Set",
 892though setting one might have the effect of setting or unsetting other
 893attributes or even returning other attributes to the "Unspecified"
 894state.
 895
 896
 897DEFINING MACRO ATTRIBUTES
 898-------------------------
 899
 900Custom macro attributes can be defined only in the `.gitattributes`
 901file at the toplevel (i.e. not in any subdirectory).  The built-in
 902macro attribute "binary" is equivalent to:
 903
 904------------
 905[attr]binary -diff -text
 906------------
 907
 908
 909EXAMPLE
 910-------
 911
 912If you have these three `gitattributes` file:
 913
 914----------------------------------------------------------------
 915(in $GIT_DIR/info/attributes)
 916
 917a*      foo !bar -baz
 918
 919(in .gitattributes)
 920abc     foo bar baz
 921
 922(in t/.gitattributes)
 923ab*     merge=filfre
 924abc     -foo -bar
 925*.c     frotz
 926----------------------------------------------------------------
 927
 928the attributes given to path `t/abc` are computed as follows:
 929
 9301. By examining `t/.gitattributes` (which is in the same
 931   directory as the path in question), git finds that the first
 932   line matches.  `merge` attribute is set.  It also finds that
 933   the second line matches, and attributes `foo` and `bar`
 934   are unset.
 935
 9362. Then it examines `.gitattributes` (which is in the parent
 937   directory), and finds that the first line matches, but
 938   `t/.gitattributes` file already decided how `merge`, `foo`
 939   and `bar` attributes should be given to this path, so it
 940   leaves `foo` and `bar` unset.  Attribute `baz` is set.
 941
 9423. Finally it examines `$GIT_DIR/info/attributes`.  This file
 943   is used to override the in-tree settings.  The first line is
 944   a match, and `foo` is set, `bar` is reverted to unspecified
 945   state, and `baz` is unset.
 946
 947As the result, the attributes assignment to `t/abc` becomes:
 948
 949----------------------------------------------------------------
 950foo     set to true
 951bar     unspecified
 952baz     set to false
 953merge   set to string value "filfre"
 954frotz   unspecified
 955----------------------------------------------------------------
 956
 957
 958SEE ALSO
 959--------
 960linkgit:git-check-attr[1].
 961
 962GIT
 963---
 964Part of the linkgit:git[1] suite