Documentation / gitattributes.txton commit Add global and system-wide gitattributes (6df42ab)
   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
 327
 328Interaction between checkin/checkout attributes
 329^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 330
 331In the check-in codepath, the worktree file is first converted
 332with `filter` driver (if specified and corresponding driver
 333defined), then the result is processed with `ident` (if
 334specified), and then finally with `text` (again, if specified
 335and applicable).
 336
 337In the check-out codepath, the blob content is first converted
 338with `text`, and then `ident` and fed to `filter`.
 339
 340
 341Generating diff text
 342~~~~~~~~~~~~~~~~~~~~
 343
 344`diff`
 345^^^^^^
 346
 347The attribute `diff` affects how 'git' generates diffs for particular
 348files. It can tell git whether to generate a textual patch for the path
 349or to treat the path as a binary file.  It can also affect what line is
 350shown on the hunk header `@@ -k,l +n,m @@` line, tell git to use an
 351external command to generate the diff, or ask git to convert binary
 352files to a text format before generating the diff.
 353
 354Set::
 355
 356        A path to which the `diff` attribute is set is treated
 357        as text, even when they contain byte values that
 358        normally never appear in text files, such as NUL.
 359
 360Unset::
 361
 362        A path to which the `diff` attribute is unset will
 363        generate `Binary files differ` (or a binary patch, if
 364        binary patches are enabled).
 365
 366Unspecified::
 367
 368        A path to which the `diff` attribute is unspecified
 369        first gets its contents inspected, and if it looks like
 370        text, it is treated as text.  Otherwise it would
 371        generate `Binary files differ`.
 372
 373String::
 374
 375        Diff is shown using the specified diff driver.  Each driver may
 376        specify one or more options, as described in the following
 377        section. The options for the diff driver "foo" are defined
 378        by the configuration variables in the "diff.foo" section of the
 379        git config file.
 380
 381
 382Defining an external diff driver
 383^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 384
 385The definition of a diff driver is done in `gitconfig`, not
 386`gitattributes` file, so strictly speaking this manual page is a
 387wrong place to talk about it.  However...
 388
 389To define an external diff driver `jcdiff`, add a section to your
 390`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 391
 392----------------------------------------------------------------
 393[diff "jcdiff"]
 394        command = j-c-diff
 395----------------------------------------------------------------
 396
 397When git needs to show you a diff for the path with `diff`
 398attribute set to `jcdiff`, it calls the command you specified
 399with the above configuration, i.e. `j-c-diff`, with 7
 400parameters, just like `GIT_EXTERNAL_DIFF` program is called.
 401See linkgit:git[1] for details.
 402
 403
 404Defining a custom hunk-header
 405^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 406
 407Each group of changes (called a "hunk") in the textual diff output
 408is prefixed with a line of the form:
 409
 410        @@ -k,l +n,m @@ TEXT
 411
 412This is called a 'hunk header'.  The "TEXT" portion is by default a line
 413that begins with an alphabet, an underscore or a dollar sign; this
 414matches what GNU 'diff -p' output uses.  This default selection however
 415is not suited for some contents, and you can use a customized pattern
 416to make a selection.
 417
 418First, in .gitattributes, you would assign the `diff` attribute
 419for paths.
 420
 421------------------------
 422*.tex   diff=tex
 423------------------------
 424
 425Then, you would define a "diff.tex.xfuncname" configuration to
 426specify a regular expression that matches a line that you would
 427want to appear as the hunk header "TEXT". Add a section to your
 428`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 429
 430------------------------
 431[diff "tex"]
 432        xfuncname = "^(\\\\(sub)*section\\{.*)$"
 433------------------------
 434
 435Note.  A single level of backslashes are eaten by the
 436configuration file parser, so you would need to double the
 437backslashes; the pattern above picks a line that begins with a
 438backslash, and zero or more occurrences of `sub` followed by
 439`section` followed by open brace, to the end of line.
 440
 441There are a few built-in patterns to make this easier, and `tex`
 442is one of them, so you do not have to write the above in your
 443configuration file (you still need to enable this with the
 444attribute mechanism, via `.gitattributes`).  The following built in
 445patterns are available:
 446
 447- `bibtex` suitable for files with BibTeX coded references.
 448
 449- `cpp` suitable for source code in the C and C++ languages.
 450
 451- `html` suitable for HTML/XHTML documents.
 452
 453- `java` suitable for source code in the Java language.
 454
 455- `objc` suitable for source code in the Objective-C language.
 456
 457- `pascal` suitable for source code in the Pascal/Delphi language.
 458
 459- `php` suitable for source code in the PHP language.
 460
 461- `python` suitable for source code in the Python language.
 462
 463- `ruby` suitable for source code in the Ruby language.
 464
 465- `tex` suitable for source code for LaTeX documents.
 466
 467
 468Customizing word diff
 469^^^^^^^^^^^^^^^^^^^^^
 470
 471You can customize the rules that `git diff --word-diff` uses to
 472split words in a line, by specifying an appropriate regular expression
 473in the "diff.*.wordRegex" configuration variable.  For example, in TeX
 474a backslash followed by a sequence of letters forms a command, but
 475several such commands can be run together without intervening
 476whitespace.  To separate them, use a regular expression in your
 477`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 478
 479------------------------
 480[diff "tex"]
 481        wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+"
 482------------------------
 483
 484A built-in pattern is provided for all languages listed in the
 485previous section.
 486
 487
 488Performing text diffs of binary files
 489^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 490
 491Sometimes it is desirable to see the diff of a text-converted
 492version of some binary files. For example, a word processor
 493document can be converted to an ASCII text representation, and
 494the diff of the text shown. Even though this conversion loses
 495some information, the resulting diff is useful for human
 496viewing (but cannot be applied directly).
 497
 498The `textconv` config option is used to define a program for
 499performing such a conversion. The program should take a single
 500argument, the name of a file to convert, and produce the
 501resulting text on stdout.
 502
 503For example, to show the diff of the exif information of a
 504file instead of the binary information (assuming you have the
 505exif tool installed), add the following section to your
 506`$GIT_DIR/config` file (or `$HOME/.gitconfig` file):
 507
 508------------------------
 509[diff "jpg"]
 510        textconv = exif
 511------------------------
 512
 513NOTE: The text conversion is generally a one-way conversion;
 514in this example, we lose the actual image contents and focus
 515just on the text data. This means that diffs generated by
 516textconv are _not_ suitable for applying. For this reason,
 517only `git diff` and the `git log` family of commands (i.e.,
 518log, whatchanged, show) will perform text conversion. `git
 519format-patch` will never generate this output. If you want to
 520send somebody a text-converted diff of a binary file (e.g.,
 521because it quickly conveys the changes you have made), you
 522should generate it separately and send it as a comment _in
 523addition to_ the usual binary diff that you might send.
 524
 525Because text conversion can be slow, especially when doing a
 526large number of them with `git log -p`, git provides a mechanism
 527to cache the output and use it in future diffs.  To enable
 528caching, set the "cachetextconv" variable in your diff driver's
 529config. For example:
 530
 531------------------------
 532[diff "jpg"]
 533        textconv = exif
 534        cachetextconv = true
 535------------------------
 536
 537This will cache the result of running "exif" on each blob
 538indefinitely. If you change the textconv config variable for a
 539diff driver, git will automatically invalidate the cache entries
 540and re-run the textconv filter. If you want to invalidate the
 541cache manually (e.g., because your version of "exif" was updated
 542and now produces better output), you can remove the cache
 543manually with `git update-ref -d refs/notes/textconv/jpg` (where
 544"jpg" is the name of the diff driver, as in the example above).
 545
 546Performing a three-way merge
 547~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 548
 549`merge`
 550^^^^^^^
 551
 552The attribute `merge` affects how three versions of a file is
 553merged when a file-level merge is necessary during `git merge`,
 554and other commands such as `git revert` and `git cherry-pick`.
 555
 556Set::
 557
 558        Built-in 3-way merge driver is used to merge the
 559        contents in a way similar to 'merge' command of `RCS`
 560        suite.  This is suitable for ordinary text files.
 561
 562Unset::
 563
 564        Take the version from the current branch as the
 565        tentative merge result, and declare that the merge has
 566        conflicts.  This is suitable for binary files that does
 567        not have a well-defined merge semantics.
 568
 569Unspecified::
 570
 571        By default, this uses the same built-in 3-way merge
 572        driver as is the case the `merge` attribute is set.
 573        However, `merge.default` configuration variable can name
 574        different merge driver to be used for paths to which the
 575        `merge` attribute is unspecified.
 576
 577String::
 578
 579        3-way merge is performed using the specified custom
 580        merge driver.  The built-in 3-way merge driver can be
 581        explicitly specified by asking for "text" driver; the
 582        built-in "take the current branch" driver can be
 583        requested with "binary".
 584
 585
 586Built-in merge drivers
 587^^^^^^^^^^^^^^^^^^^^^^
 588
 589There are a few built-in low-level merge drivers defined that
 590can be asked for via the `merge` attribute.
 591
 592text::
 593
 594        Usual 3-way file level merge for text files.  Conflicted
 595        regions are marked with conflict markers `<<<<<<<`,
 596        `=======` and `>>>>>>>`.  The version from your branch
 597        appears before the `=======` marker, and the version
 598        from the merged branch appears after the `=======`
 599        marker.
 600
 601binary::
 602
 603        Keep the version from your branch in the work tree, but
 604        leave the path in the conflicted state for the user to
 605        sort out.
 606
 607union::
 608
 609        Run 3-way file level merge for text files, but take
 610        lines from both versions, instead of leaving conflict
 611        markers.  This tends to leave the added lines in the
 612        resulting file in random order and the user should
 613        verify the result. Do not use this if you do not
 614        understand the implications.
 615
 616
 617Defining a custom merge driver
 618^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 619
 620The definition of a merge driver is done in the `.git/config`
 621file, not in the `gitattributes` file, so strictly speaking this
 622manual page is a wrong place to talk about it.  However...
 623
 624To define a custom merge driver `filfre`, add a section to your
 625`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
 626
 627----------------------------------------------------------------
 628[merge "filfre"]
 629        name = feel-free merge driver
 630        driver = filfre %O %A %B
 631        recursive = binary
 632----------------------------------------------------------------
 633
 634The `merge.*.name` variable gives the driver a human-readable
 635name.
 636
 637The `merge.*.driver` variable's value is used to construct a
 638command to run to merge ancestor's version (`%O`), current
 639version (`%A`) and the other branches' version (`%B`).  These
 640three tokens are replaced with the names of temporary files that
 641hold the contents of these versions when the command line is
 642built. Additionally, %L will be replaced with the conflict marker
 643size (see below).
 644
 645The merge driver is expected to leave the result of the merge in
 646the file named with `%A` by overwriting it, and exit with zero
 647status if it managed to merge them cleanly, or non-zero if there
 648were conflicts.
 649
 650The `merge.*.recursive` variable specifies what other merge
 651driver to use when the merge driver is called for an internal
 652merge between common ancestors, when there are more than one.
 653When left unspecified, the driver itself is used for both
 654internal merge and the final merge.
 655
 656
 657`conflict-marker-size`
 658^^^^^^^^^^^^^^^^^^^^^^
 659
 660This attribute controls the length of conflict markers left in
 661the work tree file during a conflicted merge.  Only setting to
 662the value to a positive integer has any meaningful effect.
 663
 664For example, this line in `.gitattributes` can be used to tell the merge
 665machinery to leave much longer (instead of the usual 7-character-long)
 666conflict markers when merging the file `Documentation/git-merge.txt`
 667results in a conflict.
 668
 669------------------------
 670Documentation/git-merge.txt     conflict-marker-size=32
 671------------------------
 672
 673
 674Checking whitespace errors
 675~~~~~~~~~~~~~~~~~~~~~~~~~~
 676
 677`whitespace`
 678^^^^^^^^^^^^
 679
 680The `core.whitespace` configuration variable allows you to define what
 681'diff' and 'apply' should consider whitespace errors for all paths in
 682the project (See linkgit:git-config[1]).  This attribute gives you finer
 683control per path.
 684
 685Set::
 686
 687        Notice all types of potential whitespace errors known to git.
 688
 689Unset::
 690
 691        Do not notice anything as error.
 692
 693Unspecified::
 694
 695        Use the value of `core.whitespace` configuration variable to
 696        decide what to notice as error.
 697
 698String::
 699
 700        Specify a comma separate list of common whitespace problems to
 701        notice in the same format as `core.whitespace` configuration
 702        variable.
 703
 704
 705Creating an archive
 706~~~~~~~~~~~~~~~~~~~
 707
 708`export-ignore`
 709^^^^^^^^^^^^^^^
 710
 711Files and directories with the attribute `export-ignore` won't be added to
 712archive files.
 713
 714`export-subst`
 715^^^^^^^^^^^^^^
 716
 717If the attribute `export-subst` is set for a file then git will expand
 718several placeholders when adding this file to an archive.  The
 719expansion depends on the availability of a commit ID, i.e., if
 720linkgit:git-archive[1] has been given a tree instead of a commit or a
 721tag then no replacement will be done.  The placeholders are the same
 722as those for the option `--pretty=format:` of linkgit:git-log[1],
 723except that they need to be wrapped like this: `$Format:PLACEHOLDERS$`
 724in the file.  E.g. the string `$Format:%H$` will be replaced by the
 725commit hash.
 726
 727
 728Packing objects
 729~~~~~~~~~~~~~~~
 730
 731`delta`
 732^^^^^^^
 733
 734Delta compression will not be attempted for blobs for paths with the
 735attribute `delta` set to false.
 736
 737
 738Viewing files in GUI tools
 739~~~~~~~~~~~~~~~~~~~~~~~~~~
 740
 741`encoding`
 742^^^^^^^^^^
 743
 744The value of this attribute specifies the character encoding that should
 745be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to
 746display the contents of the relevant file. Note that due to performance
 747considerations linkgit:gitk[1] does not use this attribute unless you
 748manually enable per-file encodings in its options.
 749
 750If this attribute is not set or has an invalid value, the value of the
 751`gui.encoding` configuration variable is used instead
 752(See linkgit:git-config[1]).
 753
 754
 755USING ATTRIBUTE MACROS
 756----------------------
 757
 758You do not want any end-of-line conversions applied to, nor textual diffs
 759produced for, any binary file you track.  You would need to specify e.g.
 760
 761------------
 762*.jpg -text -diff
 763------------
 764
 765but that may become cumbersome, when you have many attributes.  Using
 766attribute macros, you can specify groups of attributes set or unset at
 767the same time.  The system knows a built-in attribute macro, `binary`:
 768
 769------------
 770*.jpg binary
 771------------
 772
 773which is equivalent to the above.  Note that the attribute macros can only
 774be "Set" (see the above example that sets "binary" macro as if it were an
 775ordinary attribute --- setting it in turn unsets "text" and "diff").
 776
 777
 778DEFINING ATTRIBUTE MACROS
 779-------------------------
 780
 781Custom attribute macros can be defined only in the `.gitattributes` file
 782at the toplevel (i.e. not in any subdirectory).  The built-in attribute
 783macro "binary" is equivalent to:
 784
 785------------
 786[attr]binary -diff -text
 787------------
 788
 789
 790EXAMPLE
 791-------
 792
 793If you have these three `gitattributes` file:
 794
 795----------------------------------------------------------------
 796(in $GIT_DIR/info/attributes)
 797
 798a*      foo !bar -baz
 799
 800(in .gitattributes)
 801abc     foo bar baz
 802
 803(in t/.gitattributes)
 804ab*     merge=filfre
 805abc     -foo -bar
 806*.c     frotz
 807----------------------------------------------------------------
 808
 809the attributes given to path `t/abc` are computed as follows:
 810
 8111. By examining `t/.gitattributes` (which is in the same
 812   directory as the path in question), git finds that the first
 813   line matches.  `merge` attribute is set.  It also finds that
 814   the second line matches, and attributes `foo` and `bar`
 815   are unset.
 816
 8172. Then it examines `.gitattributes` (which is in the parent
 818   directory), and finds that the first line matches, but
 819   `t/.gitattributes` file already decided how `merge`, `foo`
 820   and `bar` attributes should be given to this path, so it
 821   leaves `foo` and `bar` unset.  Attribute `baz` is set.
 822
 8233. Finally it examines `$GIT_DIR/info/attributes`.  This file
 824   is used to override the in-tree settings.  The first line is
 825   a match, and `foo` is set, `bar` is reverted to unspecified
 826   state, and `baz` is unset.
 827
 828As the result, the attributes assignment to `t/abc` becomes:
 829
 830----------------------------------------------------------------
 831foo     set to true
 832bar     unspecified
 833baz     set to false
 834merge   set to string value "filfre"
 835frotz   unspecified
 836----------------------------------------------------------------
 837
 838
 839
 840GIT
 841---
 842Part of the linkgit:git[1] suite