Documentation / gitattributes.txton commit Merge branch 'nd/maint-hide-checkout-index-from-error' into maint (5b57076)
   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).
  66
  67If you wish to affect only a single repository (i.e., to assign
  68attributes to files that are particular to one user's workflow), then
  69attributes should be placed in the `$GIT_DIR/info/attributes` file.
  70Attributes which should be version-controlled and distributed to other
  71repositories (i.e., attributes of interest to all users) should go into
  72`.gitattributes` files.
  73
  74Sometimes you would need to override an setting of an attribute
  75for a path to `unspecified` state.  This can be done by listing
  76the name of the attribute prefixed with an exclamation point `!`.
  77
  78
  79EFFECTS
  80-------
  81
  82Certain operations by git can be influenced by assigning
  83particular attributes to a path.  Currently, the following
  84operations are attributes-aware.
  85
  86Checking-out and checking-in
  87~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  88
  89These attributes affect how the contents stored in the
  90repository are copied to the working tree files when commands
  91such as 'git checkout' and 'git merge' run.  They also affect how
  92git stores the contents you prepare in the working tree in the
  93repository upon 'git add' and 'git commit'.
  94
  95`text`
  96^^^^^^
  97
  98This attribute enables and controls end-of-line normalization.  When a
  99text file is normalized, its line endings are converted to LF in the
 100repository.  To control what line ending style is used in the working
 101directory, use the `eol` attribute for a single file and the
 102`core.eol` configuration variable for all text files.
 103
 104Set::
 105
 106        Setting the `text` attribute on a path enables end-of-line
 107        normalization and marks the path as a text file.  End-of-line
 108        conversion takes place without guessing the content type.
 109
 110Unset::
 111
 112        Unsetting the `text` attribute on a path tells git not to
 113        attempt any end-of-line conversion upon checkin or checkout.
 114
 115Set to string value "auto"::
 116
 117        When `text` is set to "auto", the path is marked for automatic
 118        end-of-line normalization.  If git decides that the content is
 119        text, its line endings are normalized to LF on checkin.
 120
 121Unspecified::
 122
 123        If the `text` attribute is unspecified, git uses the
 124        `core.autocrlf` configuration variable to determine if the
 125        file should be converted.
 126
 127Any other value causes git to act as if `text` has been left
 128unspecified.
 129
 130`eol`
 131^^^^^
 132
 133This attribute sets a specific line-ending style to be used in the
 134working directory.  It enables end-of-line normalization without any
 135content checks, effectively setting the `text` attribute.
 136
 137Set to string value "crlf"::
 138
 139        This setting forces git to normalize line endings for this
 140        file on checkin and convert them to CRLF when the file is
 141        checked out.
 142
 143Set to string value "lf"::
 144
 145        This setting forces git to normalize line endings to LF on
 146        checkin and prevents conversion to CRLF when the file is
 147        checked out.
 148
 149Backwards compatibility with `crlf` attribute
 150^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 151
 152For backwards compatibility, the `crlf` attribute is interpreted as
 153follows:
 154
 155------------------------
 156crlf            text
 157-crlf           -text
 158crlf=input      eol=lf
 159------------------------
 160
 161End-of-line conversion
 162^^^^^^^^^^^^^^^^^^^^^^
 163
 164While git normally leaves file contents alone, it can be configured to
 165normalize line endings to LF in the repository and, optionally, to
 166convert them to CRLF when files are checked out.
 167
 168Here is an example that will make git normalize .txt, .vcproj and .sh
 169files, ensure that .vcproj files have CRLF and .sh files have LF in
 170the working directory, and prevent .jpg files from being normalized
 171regardless of their content.
 172
 173------------------------
 174*.txt           text
 175*.vcproj        eol=crlf
 176*.sh            eol=lf
 177*.jpg           -text
 178------------------------
 179
 180Other source code management systems normalize all text files in their
 181repositories, and there are two ways to enable similar automatic
 182normalization in git.
 183
 184If you simply want to have CRLF line endings in your working directory
 185regardless of the repository you are working with, you can set the
 186config variable "core.autocrlf" without changing any attributes.
 187
 188------------------------
 189[core]
 190        autocrlf = true
 191------------------------
 192
 193This does not force normalization of all text files, but does ensure
 194that text files that you introduce to the repository have their line
 195endings normalized to LF when they are added, and that files that are
 196already normalized in the repository stay normalized.
 197
 198If you want to interoperate with a source code management system that
 199enforces end-of-line normalization, or you simply want all text files
 200in your repository to be normalized, you should instead set the `text`
 201attribute to "auto" for _all_ files.
 202
 203------------------------
 204*       text=auto
 205------------------------
 206
 207This ensures that all files that git considers to be text will have
 208normalized (LF) line endings in the repository.  The `core.eol`
 209configuration variable controls which line endings git will use for
 210normalized files in your working directory; the default is to use the
 211native line ending for your platform, or CRLF if `core.autocrlf` is
 212set.
 213
 214NOTE: When `text=auto` normalization is enabled in an existing
 215repository, any text files containing CRLFs should be normalized.  If
 216they are not they will be normalized the next time someone tries to
 217change them, causing unfortunate misattribution.  From a clean working
 218directory:
 219
 220-------------------------------------------------
 221$ echo "* text=auto" >>.gitattributes
 222$ rm .git/index     # Remove the index to force git to
 223$ git reset         # re-scan the working directory
 224$ git status        # Show files that will be normalized
 225$ git add -u
 226$ git add .gitattributes
 227$ git commit -m "Introduce end-of-line normalization"
 228-------------------------------------------------
 229
 230If any files that should not be normalized show up in 'git status',
 231unset their `text` attribute before running 'git add -u'.
 232
 233------------------------
 234manual.pdf      -text
 235------------------------
 236
 237Conversely, text files that git does not detect can have normalization
 238enabled manually.
 239
 240------------------------
 241weirdchars.txt  text
 242------------------------
 243
 244If `core.safecrlf` is set to "true" or "warn", git verifies if
 245the conversion is reversible for the current setting of
 246`core.autocrlf`.  For "true", git rejects irreversible
 247conversions; for "warn", git only prints a warning but accepts
 248an irreversible conversion.  The safety triggers to prevent such
 249a conversion done to the files in the work tree, but there are a
 250few exceptions.  Even though...
 251
 252- 'git add' itself does not touch the files in the work tree, the
 253  next checkout would, so the safety triggers;
 254
 255- 'git apply' to update a text file with a patch does touch the files
 256  in the work tree, but the operation is about text files and CRLF
 257  conversion is about fixing the line ending inconsistencies, so the
 258  safety does not trigger;
 259
 260- 'git diff' itself does not touch the files in the work tree, it is
 261  often run to inspect the changes you intend to next 'git add'.  To
 262  catch potential problems early, safety triggers.
 263
 264
 265`ident`
 266^^^^^^^
 267
 268When the attribute `ident` is set for a path, git replaces
 269`$Id$` in the blob object with `$Id:`, followed by the
 27040-character hexadecimal blob object name, followed by a dollar
 271sign `$` upon checkout.  Any byte sequence that begins with
 272`$Id:` and ends with `$` in the worktree file is replaced
 273with `$Id$` upon check-in.
 274
 275
 276`filter`
 277^^^^^^^^
 278
 279A `filter` attribute can be set to a string value that names a
 280filter driver specified in the configuration.
 281
 282A filter driver consists of a `clean` command and a `smudge`
 283command, either of which can be left unspecified.  Upon
 284checkout, when the `smudge` command is specified, the command is
 285fed the blob object from its standard input, and its standard
 286output is used to update the worktree file.  Similarly, the
 287`clean` command is used to convert the contents of worktree file
 288upon checkin.
 289
 290A missing filter driver definition in the config is not an error
 291but makes the filter a no-op passthru.
 292
 293The content filtering is done to massage the content into a
 294shape that is more convenient for the platform, filesystem, and
 295the user to use.  The key phrase here is "more convenient" and not
 296"turning something unusable into usable".  In other words, the
 297intent is that if someone unsets the filter driver definition,
 298or does not have the appropriate filter program, the project
 299should still be usable.
 300
 301For example, in .gitattributes, you would assign the `filter`
 302attribute for paths.
 303
 304------------------------
 305*.c     filter=indent
 306------------------------
 307
 308Then you would define a "filter.indent.clean" and "filter.indent.smudge"
 309configuration in your .git/config to specify a pair of commands to
 310modify the contents of C programs when the source files are checked
 311in ("clean" is run) and checked out (no change is made because the
 312command is "cat").
 313
 314------------------------
 315[filter "indent"]
 316        clean = indent
 317        smudge = cat
 318------------------------
 319
 320For best results, `clean` should not alter its output further if it is
 321run twice ("clean->clean" should be equivalent to "clean"), and
 322multiple `smudge` commands should not alter `clean`'s output
 323("smudge->smudge->clean" should be equivalent to "clean").  See the
 324section on merging below.
 325
 326The "indent" filter is well-behaved in this regard: it will not modify
 327input that is already correctly indented.  In this case, the lack of a
 328smudge filter means that the clean filter _must_ accept its own output
 329without modifying it.
 330
 331
 332Interaction between checkin/checkout attributes
 333^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 334
 335In the check-in codepath, the worktree file is first converted
 336with `filter` driver (if specified and corresponding driver
 337defined), then the result is processed with `ident` (if
 338specified), and then finally with `text` (again, if specified
 339and applicable).
 340
 341In the check-out codepath, the blob content is first converted
 342with `text`, and then `ident` and fed to `filter`.
 343
 344
 345Merging branches with differing checkin/checkout attributes
 346^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 347
 348If you have added attributes to a file that cause the canonical
 349repository format for that file to change, such as adding a
 350clean/smudge filter or text/eol/ident attributes, merging anything
 351where the attribute is not in place would normally cause merge
 352conflicts.
 353
 354To prevent these unnecessary merge conflicts, git can be told to run a
 355virtual check-out and check-in of all three stages of a file when
 356resolving a three-way merge by setting the `merge.renormalize`
 357configuration variable.  This prevents changes caused by check-in
 358conversion from causing spurious merge conflicts when a converted file
 359is merged with an unconverted file.
 360
 361As long as a "smudge->clean" results in the same output as a "clean"
 362even on files that are already smudged, this strategy will
 363automatically resolve all filter-related conflicts.  Filters that do
 364not act in this way may cause additional merge conflicts that must be
 365resolved manually.
 366
 367
 368Generating diff text
 369~~~~~~~~~~~~~~~~~~~~
 370
 371`diff`
 372^^^^^^
 373
 374The attribute `diff` affects how 'git' generates diffs for particular
 375files. It can tell git whether to generate a textual patch for the path
 376or to treat the path as a binary file.  It can also affect what line is
 377shown on the hunk header `@@ -k,l +n,m @@` line, tell git to use an
 378external command to generate the diff, or ask git to convert binary
 379files to a text format before generating the diff.
 380
 381Set::
 382
 383        A path to which the `diff` attribute is set is treated
 384        as text, even when they contain byte values that
 385        normally never appear in text files, such as NUL.
 386
 387Unset::
 388
 389        A path to which the `diff` attribute is unset will
 390        generate `Binary files differ` (or a binary patch, if
 391        binary patches are enabled).
 392
 393Unspecified::
 394
 395        A path to which the `diff` attribute is unspecified
 396        first gets its contents inspected, and if it looks like
 397        text, it is treated as text.  Otherwise it would
 398        generate `Binary files differ`.
 399
 400String::
 401
 402        Diff is shown using the specified diff driver.  Each driver may
 403        specify one or more options, as described in the following
 404        section. The options for the diff driver "foo" are defined
 405        by the configuration variables in the "diff.foo" section of the
 406        git config file.
 407
 408
 409Defining an external diff driver
 410^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 411
 412The definition of a diff driver is done in `gitconfig`, not
 413`gitattributes` file, so strictly speaking this manual page is a
 414wrong place to talk about it.  However...
 415
 416To define an external diff driver `jcdiff`, add a section to your
 417`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 418
 419----------------------------------------------------------------
 420[diff "jcdiff"]
 421        command = j-c-diff
 422----------------------------------------------------------------
 423
 424When git needs to show you a diff for the path with `diff`
 425attribute set to `jcdiff`, it calls the command you specified
 426with the above configuration, i.e. `j-c-diff`, with 7
 427parameters, just like `GIT_EXTERNAL_DIFF` program is called.
 428See linkgit:git[1] for details.
 429
 430
 431Defining a custom hunk-header
 432^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 433
 434Each group of changes (called a "hunk") in the textual diff output
 435is prefixed with a line of the form:
 436
 437        @@ -k,l +n,m @@ TEXT
 438
 439This is called a 'hunk header'.  The "TEXT" portion is by default a line
 440that begins with an alphabet, an underscore or a dollar sign; this
 441matches what GNU 'diff -p' output uses.  This default selection however
 442is not suited for some contents, and you can use a customized pattern
 443to make a selection.
 444
 445First, in .gitattributes, you would assign the `diff` attribute
 446for paths.
 447
 448------------------------
 449*.tex   diff=tex
 450------------------------
 451
 452Then, you would define a "diff.tex.xfuncname" configuration to
 453specify a regular expression that matches a line that you would
 454want to appear as the hunk header "TEXT". Add a section to your
 455`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 456
 457------------------------
 458[diff "tex"]
 459        xfuncname = "^(\\\\(sub)*section\\{.*)$"
 460------------------------
 461
 462Note.  A single level of backslashes are eaten by the
 463configuration file parser, so you would need to double the
 464backslashes; the pattern above picks a line that begins with a
 465backslash, and zero or more occurrences of `sub` followed by
 466`section` followed by open brace, to the end of line.
 467
 468There are a few built-in patterns to make this easier, and `tex`
 469is one of them, so you do not have to write the above in your
 470configuration file (you still need to enable this with the
 471attribute mechanism, via `.gitattributes`).  The following built in
 472patterns are available:
 473
 474- `bibtex` suitable for files with BibTeX coded references.
 475
 476- `cpp` suitable for source code in the C and C++ languages.
 477
 478- `csharp` suitable for source code in the C# language.
 479
 480- `fortran` suitable for source code in the Fortran language.
 481
 482- `html` suitable for HTML/XHTML documents.
 483
 484- `java` suitable for source code in the Java language.
 485
 486- `objc` suitable for source code in the Objective-C language.
 487
 488- `pascal` suitable for source code in the Pascal/Delphi language.
 489
 490- `php` suitable for source code in the PHP language.
 491
 492- `python` suitable for source code in the Python language.
 493
 494- `ruby` suitable for source code in the Ruby language.
 495
 496- `tex` suitable for source code for LaTeX documents.
 497
 498
 499Customizing word diff
 500^^^^^^^^^^^^^^^^^^^^^
 501
 502You can customize the rules that `git diff --word-diff` uses to
 503split words in a line, by specifying an appropriate regular expression
 504in the "diff.*.wordRegex" configuration variable.  For example, in TeX
 505a backslash followed by a sequence of letters forms a command, but
 506several such commands can be run together without intervening
 507whitespace.  To separate them, use a regular expression in your
 508`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 509
 510------------------------
 511[diff "tex"]
 512        wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+"
 513------------------------
 514
 515A built-in pattern is provided for all languages listed in the
 516previous section.
 517
 518
 519Performing text diffs of binary files
 520^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 521
 522Sometimes it is desirable to see the diff of a text-converted
 523version of some binary files. For example, a word processor
 524document can be converted to an ASCII text representation, and
 525the diff of the text shown. Even though this conversion loses
 526some information, the resulting diff is useful for human
 527viewing (but cannot be applied directly).
 528
 529The `textconv` config option is used to define a program for
 530performing such a conversion. The program should take a single
 531argument, the name of a file to convert, and produce the
 532resulting text on stdout.
 533
 534For example, to show the diff of the exif information of a
 535file instead of the binary information (assuming you have the
 536exif tool installed), add the following section to your
 537`$GIT_DIR/config` file (or `$HOME/.gitconfig` file):
 538
 539------------------------
 540[diff "jpg"]
 541        textconv = exif
 542------------------------
 543
 544NOTE: The text conversion is generally a one-way conversion;
 545in this example, we lose the actual image contents and focus
 546just on the text data. This means that diffs generated by
 547textconv are _not_ suitable for applying. For this reason,
 548only `git diff` and the `git log` family of commands (i.e.,
 549log, whatchanged, show) will perform text conversion. `git
 550format-patch` will never generate this output. If you want to
 551send somebody a text-converted diff of a binary file (e.g.,
 552because it quickly conveys the changes you have made), you
 553should generate it separately and send it as a comment _in
 554addition to_ the usual binary diff that you might send.
 555
 556Because text conversion can be slow, especially when doing a
 557large number of them with `git log -p`, git provides a mechanism
 558to cache the output and use it in future diffs.  To enable
 559caching, set the "cachetextconv" variable in your diff driver's
 560config. For example:
 561
 562------------------------
 563[diff "jpg"]
 564        textconv = exif
 565        cachetextconv = true
 566------------------------
 567
 568This will cache the result of running "exif" on each blob
 569indefinitely. If you change the textconv config variable for a
 570diff driver, git will automatically invalidate the cache entries
 571and re-run the textconv filter. If you want to invalidate the
 572cache manually (e.g., because your version of "exif" was updated
 573and now produces better output), you can remove the cache
 574manually with `git update-ref -d refs/notes/textconv/jpg` (where
 575"jpg" is the name of the diff driver, as in the example above).
 576
 577Performing a three-way merge
 578~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 579
 580`merge`
 581^^^^^^^
 582
 583The attribute `merge` affects how three versions of a file is
 584merged when a file-level merge is necessary during `git merge`,
 585and other commands such as `git revert` and `git cherry-pick`.
 586
 587Set::
 588
 589        Built-in 3-way merge driver is used to merge the
 590        contents in a way similar to 'merge' command of `RCS`
 591        suite.  This is suitable for ordinary text files.
 592
 593Unset::
 594
 595        Take the version from the current branch as the
 596        tentative merge result, and declare that the merge has
 597        conflicts.  This is suitable for binary files that does
 598        not have a well-defined merge semantics.
 599
 600Unspecified::
 601
 602        By default, this uses the same built-in 3-way merge
 603        driver as is the case the `merge` attribute is set.
 604        However, `merge.default` configuration variable can name
 605        different merge driver to be used for paths to which the
 606        `merge` attribute is unspecified.
 607
 608String::
 609
 610        3-way merge is performed using the specified custom
 611        merge driver.  The built-in 3-way merge driver can be
 612        explicitly specified by asking for "text" driver; the
 613        built-in "take the current branch" driver can be
 614        requested with "binary".
 615
 616
 617Built-in merge drivers
 618^^^^^^^^^^^^^^^^^^^^^^
 619
 620There are a few built-in low-level merge drivers defined that
 621can be asked for via the `merge` attribute.
 622
 623text::
 624
 625        Usual 3-way file level merge for text files.  Conflicted
 626        regions are marked with conflict markers `<<<<<<<`,
 627        `=======` and `>>>>>>>`.  The version from your branch
 628        appears before the `=======` marker, and the version
 629        from the merged branch appears after the `=======`
 630        marker.
 631
 632binary::
 633
 634        Keep the version from your branch in the work tree, but
 635        leave the path in the conflicted state for the user to
 636        sort out.
 637
 638union::
 639
 640        Run 3-way file level merge for text files, but take
 641        lines from both versions, instead of leaving conflict
 642        markers.  This tends to leave the added lines in the
 643        resulting file in random order and the user should
 644        verify the result. Do not use this if you do not
 645        understand the implications.
 646
 647
 648Defining a custom merge driver
 649^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 650
 651The definition of a merge driver is done in the `.git/config`
 652file, not in the `gitattributes` file, so strictly speaking this
 653manual page is a wrong place to talk about it.  However...
 654
 655To define a custom merge driver `filfre`, add a section to your
 656`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 657
 658----------------------------------------------------------------
 659[merge "filfre"]
 660        name = feel-free merge driver
 661        driver = filfre %O %A %B
 662        recursive = binary
 663----------------------------------------------------------------
 664
 665The `merge.*.name` variable gives the driver a human-readable
 666name.
 667
 668The `merge.*.driver` variable's value is used to construct a
 669command to run to merge ancestor's version (`%O`), current
 670version (`%A`) and the other branches' version (`%B`).  These
 671three tokens are replaced with the names of temporary files that
 672hold the contents of these versions when the command line is
 673built. Additionally, %L will be replaced with the conflict marker
 674size (see below).
 675
 676The merge driver is expected to leave the result of the merge in
 677the file named with `%A` by overwriting it, and exit with zero
 678status if it managed to merge them cleanly, or non-zero if there
 679were conflicts.
 680
 681The `merge.*.recursive` variable specifies what other merge
 682driver to use when the merge driver is called for an internal
 683merge between common ancestors, when there are more than one.
 684When left unspecified, the driver itself is used for both
 685internal merge and the final merge.
 686
 687
 688`conflict-marker-size`
 689^^^^^^^^^^^^^^^^^^^^^^
 690
 691This attribute controls the length of conflict markers left in
 692the work tree file during a conflicted merge.  Only setting to
 693the value to a positive integer has any meaningful effect.
 694
 695For example, this line in `.gitattributes` can be used to tell the merge
 696machinery to leave much longer (instead of the usual 7-character-long)
 697conflict markers when merging the file `Documentation/git-merge.txt`
 698results in a conflict.
 699
 700------------------------
 701Documentation/git-merge.txt     conflict-marker-size=32
 702------------------------
 703
 704
 705Checking whitespace errors
 706~~~~~~~~~~~~~~~~~~~~~~~~~~
 707
 708`whitespace`
 709^^^^^^^^^^^^
 710
 711The `core.whitespace` configuration variable allows you to define what
 712'diff' and 'apply' should consider whitespace errors for all paths in
 713the project (See linkgit:git-config[1]).  This attribute gives you finer
 714control per path.
 715
 716Set::
 717
 718        Notice all types of potential whitespace errors known to git.
 719
 720Unset::
 721
 722        Do not notice anything as error.
 723
 724Unspecified::
 725
 726        Use the value of `core.whitespace` configuration variable to
 727        decide what to notice as error.
 728
 729String::
 730
 731        Specify a comma separate list of common whitespace problems to
 732        notice in the same format as `core.whitespace` configuration
 733        variable.
 734
 735
 736Creating an archive
 737~~~~~~~~~~~~~~~~~~~
 738
 739`export-ignore`
 740^^^^^^^^^^^^^^^
 741
 742Files and directories with the attribute `export-ignore` won't be added to
 743archive files.
 744
 745`export-subst`
 746^^^^^^^^^^^^^^
 747
 748If the attribute `export-subst` is set for a file then git will expand
 749several placeholders when adding this file to an archive.  The
 750expansion depends on the availability of a commit ID, i.e., if
 751linkgit:git-archive[1] has been given a tree instead of a commit or a
 752tag then no replacement will be done.  The placeholders are the same
 753as those for the option `--pretty=format:` of linkgit:git-log[1],
 754except that they need to be wrapped like this: `$Format:PLACEHOLDERS$`
 755in the file.  E.g. the string `$Format:%H$` will be replaced by the
 756commit hash.
 757
 758
 759Packing objects
 760~~~~~~~~~~~~~~~
 761
 762`delta`
 763^^^^^^^
 764
 765Delta compression will not be attempted for blobs for paths with the
 766attribute `delta` set to false.
 767
 768
 769Viewing files in GUI tools
 770~~~~~~~~~~~~~~~~~~~~~~~~~~
 771
 772`encoding`
 773^^^^^^^^^^
 774
 775The value of this attribute specifies the character encoding that should
 776be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to
 777display the contents of the relevant file. Note that due to performance
 778considerations linkgit:gitk[1] does not use this attribute unless you
 779manually enable per-file encodings in its options.
 780
 781If this attribute is not set or has an invalid value, the value of the
 782`gui.encoding` configuration variable is used instead
 783(See linkgit:git-config[1]).
 784
 785
 786USING ATTRIBUTE MACROS
 787----------------------
 788
 789You do not want any end-of-line conversions applied to, nor textual diffs
 790produced for, any binary file you track.  You would need to specify e.g.
 791
 792------------
 793*.jpg -text -diff
 794------------
 795
 796but that may become cumbersome, when you have many attributes.  Using
 797attribute macros, you can specify groups of attributes set or unset at
 798the same time.  The system knows a built-in attribute macro, `binary`:
 799
 800------------
 801*.jpg binary
 802------------
 803
 804which is equivalent to the above.  Note that the attribute macros can only
 805be "Set" (see the above example that sets "binary" macro as if it were an
 806ordinary attribute --- setting it in turn unsets "text" and "diff").
 807
 808
 809DEFINING ATTRIBUTE MACROS
 810-------------------------
 811
 812Custom attribute macros can be defined only in the `.gitattributes` file
 813at the toplevel (i.e. not in any subdirectory).  The built-in attribute
 814macro "binary" is equivalent to:
 815
 816------------
 817[attr]binary -diff -text
 818------------
 819
 820
 821EXAMPLE
 822-------
 823
 824If you have these three `gitattributes` file:
 825
 826----------------------------------------------------------------
 827(in $GIT_DIR/info/attributes)
 828
 829a*      foo !bar -baz
 830
 831(in .gitattributes)
 832abc     foo bar baz
 833
 834(in t/.gitattributes)
 835ab*     merge=filfre
 836abc     -foo -bar
 837*.c     frotz
 838----------------------------------------------------------------
 839
 840the attributes given to path `t/abc` are computed as follows:
 841
 8421. By examining `t/.gitattributes` (which is in the same
 843   directory as the path in question), git finds that the first
 844   line matches.  `merge` attribute is set.  It also finds that
 845   the second line matches, and attributes `foo` and `bar`
 846   are unset.
 847
 8482. Then it examines `.gitattributes` (which is in the parent
 849   directory), and finds that the first line matches, but
 850   `t/.gitattributes` file already decided how `merge`, `foo`
 851   and `bar` attributes should be given to this path, so it
 852   leaves `foo` and `bar` unset.  Attribute `baz` is set.
 853
 8543. Finally it examines `$GIT_DIR/info/attributes`.  This file
 855   is used to override the in-tree settings.  The first line is
 856   a match, and `foo` is set, `bar` is reverted to unspecified
 857   state, and `baz` is unset.
 858
 859As the result, the attributes assignment to `t/abc` becomes:
 860
 861----------------------------------------------------------------
 862foo     set to true
 863bar     unspecified
 864baz     set to false
 865merge   set to string value "filfre"
 866frotz   unspecified
 867----------------------------------------------------------------
 868
 869
 870
 871GIT
 872---
 873Part of the linkgit:git[1] suite