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diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt new file mode 100644 index 0000000000..a85b187e04 --- /dev/null +++ b/Documentation/gitattributes.txt @@ -0,0 +1,966 @@ +gitattributes(5) +================ + +NAME +---- +gitattributes - defining attributes per path + +SYNOPSIS +-------- +$GIT_DIR/info/attributes, .gitattributes + + +DESCRIPTION +----------- + +A `gitattributes` file is a simple text file that gives +`attributes` to pathnames. + +Each line in `gitattributes` file is of form: + + pattern attr1 attr2 ... + +That is, a pattern followed by an attributes list, +separated by whitespaces. When the pattern matches the +path in question, the attributes listed on the line are given to +the path. + +Each attribute can be in one of these states for a given path: + +Set:: + + The path has the attribute with special value "true"; + this is specified by listing only the name of the + attribute in the attribute list. + +Unset:: + + The path has the attribute with special value "false"; + this is specified by listing the name of the attribute + prefixed with a dash `-` in the attribute list. + +Set to a value:: + + The path has the attribute with specified string value; + this is specified by listing the name of the attribute + followed by an equal sign `=` and its value in the + attribute list. + +Unspecified:: + + No pattern matches the path, and nothing says if + the path has or does not have the attribute, the + attribute for the path is said to be Unspecified. + +When more than one pattern matches the path, a later line +overrides an earlier line. This overriding is done per +attribute. The rules how the pattern matches paths are the +same as in `.gitignore` files; see linkgit:gitignore[5]. + +When deciding what attributes are assigned to a path, git +consults `$GIT_DIR/info/attributes` file (which has the highest +precedence), `.gitattributes` file in the same directory as the +path in question, and its parent directories up to the toplevel of the +work tree (the further the directory that contains `.gitattributes` +is from the path in question, the lower its precedence). Finally +global and system-wide files are considered (they have the lowest +precedence). + +If you wish to affect only a single repository (i.e., to assign +attributes to files that are particular to +one user's workflow for that repository), then +attributes should be placed in the `$GIT_DIR/info/attributes` file. +Attributes which should be version-controlled and distributed to other +repositories (i.e., attributes of interest to all users) should go into +`.gitattributes` files. Attributes that should affect all repositories +for a single user should be placed in a file specified by the +`core.attributesfile` configuration option (see linkgit:git-config[1]). +Attributes for all users on a system should be placed in the +`$(prefix)/etc/gitattributes` file. + +Sometimes you would need to override an setting of an attribute +for a path to `Unspecified` state. This can be done by listing +the name of the attribute prefixed with an exclamation point `!`. + + +EFFECTS +------- + +Certain operations by git can be influenced by assigning +particular attributes to a path. Currently, the following +operations are attributes-aware. + +Checking-out and checking-in +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +These attributes affect how the contents stored in the +repository are copied to the working tree files when commands +such as 'git checkout' and 'git merge' run. They also affect how +git stores the contents you prepare in the working tree in the +repository upon 'git add' and 'git commit'. + +`text` +^^^^^^ + +This attribute enables and controls end-of-line normalization. When a +text file is normalized, its line endings are converted to LF in the +repository. To control what line ending style is used in the working +directory, use the `eol` attribute for a single file and the +`core.eol` configuration variable for all text files. + +Set:: + + Setting the `text` attribute on a path enables end-of-line + normalization and marks the path as a text file. End-of-line + conversion takes place without guessing the content type. + +Unset:: + + Unsetting the `text` attribute on a path tells git not to + attempt any end-of-line conversion upon checkin or checkout. + +Set to string value "auto":: + + When `text` is set to "auto", the path is marked for automatic + end-of-line normalization. If git decides that the content is + text, its line endings are normalized to LF on checkin. + +Unspecified:: + + If the `text` attribute is unspecified, git uses the + `core.autocrlf` configuration variable to determine if the + file should be converted. + +Any other value causes git to act as if `text` has been left +unspecified. + +`eol` +^^^^^ + +This attribute sets a specific line-ending style to be used in the +working directory. It enables end-of-line normalization without any +content checks, effectively setting the `text` attribute. + +Set to string value "crlf":: + + This setting forces git to normalize line endings for this + file on checkin and convert them to CRLF when the file is + checked out. + +Set to string value "lf":: + + This setting forces git to normalize line endings to LF on + checkin and prevents conversion to CRLF when the file is + checked out. + +Backwards compatibility with `crlf` attribute +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +For backwards compatibility, the `crlf` attribute is interpreted as +follows: + +------------------------ +crlf text +-crlf -text +crlf=input eol=lf +------------------------ + +End-of-line conversion +^^^^^^^^^^^^^^^^^^^^^^ + +While git normally leaves file contents alone, it can be configured to +normalize line endings to LF in the repository and, optionally, to +convert them to CRLF when files are checked out. + +Here is an example that will make git normalize .txt, .vcproj and .sh +files, ensure that .vcproj files have CRLF and .sh files have LF in +the working directory, and prevent .jpg files from being normalized +regardless of their content. + +------------------------ +*.txt text +*.vcproj eol=crlf +*.sh eol=lf +*.jpg -text +------------------------ + +Other source code management systems normalize all text files in their +repositories, and there are two ways to enable similar automatic +normalization in git. + +If you simply want to have CRLF line endings in your working directory +regardless of the repository you are working with, you can set the +config variable "core.autocrlf" without changing any attributes. + +------------------------ +[core] + autocrlf = true +------------------------ + +This does not force normalization of all text files, but does ensure +that text files that you introduce to the repository have their line +endings normalized to LF when they are added, and that files that are +already normalized in the repository stay normalized. + +If you want to interoperate with a source code management system that +enforces end-of-line normalization, or you simply want all text files +in your repository to be normalized, you should instead set the `text` +attribute to "auto" for _all_ files. + +------------------------ +* text=auto +------------------------ + +This ensures that all files that git considers to be text will have +normalized (LF) line endings in the repository. The `core.eol` +configuration variable controls which line endings git will use for +normalized files in your working directory; the default is to use the +native line ending for your platform, or CRLF if `core.autocrlf` is +set. + +NOTE: When `text=auto` normalization is enabled in an existing +repository, any text files containing CRLFs should be normalized. If +they are not they will be normalized the next time someone tries to +change them, causing unfortunate misattribution. From a clean working +directory: + +------------------------------------------------- +$ echo "* text=auto" >>.gitattributes +$ rm .git/index # Remove the index to force git to +$ git reset # re-scan the working directory +$ git status # Show files that will be normalized +$ git add -u +$ git add .gitattributes +$ git commit -m "Introduce end-of-line normalization" +------------------------------------------------- + +If any files that should not be normalized show up in 'git status', +unset their `text` attribute before running 'git add -u'. + +------------------------ +manual.pdf -text +------------------------ + +Conversely, text files that git does not detect can have normalization +enabled manually. + +------------------------ +weirdchars.txt text +------------------------ + +If `core.safecrlf` is set to "true" or "warn", git verifies if +the conversion is reversible for the current setting of +`core.autocrlf`. For "true", git rejects irreversible +conversions; for "warn", git only prints a warning but accepts +an irreversible conversion. The safety triggers to prevent such +a conversion done to the files in the work tree, but there are a +few exceptions. Even though... + +- 'git add' itself does not touch the files in the work tree, the + next checkout would, so the safety triggers; + +- 'git apply' to update a text file with a patch does touch the files + in the work tree, but the operation is about text files and CRLF + conversion is about fixing the line ending inconsistencies, so the + safety does not trigger; + +- 'git diff' itself does not touch the files in the work tree, it is + often run to inspect the changes you intend to next 'git add'. To + catch potential problems early, safety triggers. + + +`ident` +^^^^^^^ + +When the attribute `ident` is set for a path, git replaces +`$Id$` in the blob object with `$Id:`, followed by the +40-character hexadecimal blob object name, followed by a dollar +sign `$` upon checkout. Any byte sequence that begins with +`$Id:` and ends with `$` in the worktree file is replaced +with `$Id$` upon check-in. + + +`filter` +^^^^^^^^ + +A `filter` attribute can be set to a string value that names a +filter driver specified in the configuration. + +A filter driver consists of a `clean` command and a `smudge` +command, either of which can be left unspecified. Upon +checkout, when the `smudge` command is specified, the command is +fed the blob object from its standard input, and its standard +output is used to update the worktree file. Similarly, the +`clean` command is used to convert the contents of worktree file +upon checkin. + +A missing filter driver definition in the config is not an error +but makes the filter a no-op passthru. + +The content filtering is done to massage the content into a +shape that is more convenient for the platform, filesystem, and +the user to use. The key phrase here is "more convenient" and not +"turning something unusable into usable". In other words, the +intent is that if someone unsets the filter driver definition, +or does not have the appropriate filter program, the project +should still be usable. + +For example, in .gitattributes, you would assign the `filter` +attribute for paths. + +------------------------ +*.c filter=indent +------------------------ + +Then you would define a "filter.indent.clean" and "filter.indent.smudge" +configuration in your .git/config to specify a pair of commands to +modify the contents of C programs when the source files are checked +in ("clean" is run) and checked out (no change is made because the +command is "cat"). + +------------------------ +[filter "indent"] + clean = indent + smudge = cat +------------------------ + +For best results, `clean` should not alter its output further if it is +run twice ("clean->clean" should be equivalent to "clean"), and +multiple `smudge` commands should not alter `clean`'s output +("smudge->smudge->clean" should be equivalent to "clean"). See the +section on merging below. + +The "indent" filter is well-behaved in this regard: it will not modify +input that is already correctly indented. In this case, the lack of a +smudge filter means that the clean filter _must_ accept its own output +without modifying it. + +Sequence "%f" on the filter command line is replaced with the name of +the file the filter is working on. A filter might use this in keyword +substitution. For example: + +------------------------ +[filter "p4"] + clean = git-p4-filter --clean %f + smudge = git-p4-filter --smudge %f +------------------------ + + +Interaction between checkin/checkout attributes +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +In the check-in codepath, the worktree file is first converted +with `filter` driver (if specified and corresponding driver +defined), then the result is processed with `ident` (if +specified), and then finally with `text` (again, if specified +and applicable). + +In the check-out codepath, the blob content is first converted +with `text`, and then `ident` and fed to `filter`. + + +Merging branches with differing checkin/checkout attributes +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If you have added attributes to a file that cause the canonical +repository format for that file to change, such as adding a +clean/smudge filter or text/eol/ident attributes, merging anything +where the attribute is not in place would normally cause merge +conflicts. + +To prevent these unnecessary merge conflicts, git can be told to run a +virtual check-out and check-in of all three stages of a file when +resolving a three-way merge by setting the `merge.renormalize` +configuration variable. This prevents changes caused by check-in +conversion from causing spurious merge conflicts when a converted file +is merged with an unconverted file. + +As long as a "smudge->clean" results in the same output as a "clean" +even on files that are already smudged, this strategy will +automatically resolve all filter-related conflicts. Filters that do +not act in this way may cause additional merge conflicts that must be +resolved manually. + + +Generating diff text +~~~~~~~~~~~~~~~~~~~~ + +`diff` +^^^^^^ + +The attribute `diff` affects how 'git' generates diffs for particular +files. It can tell git whether to generate a textual patch for the path +or to treat the path as a binary file. It can also affect what line is +shown on the hunk header `@@ -k,l +n,m @@` line, tell git to use an +external command to generate the diff, or ask git to convert binary +files to a text format before generating the diff. + +Set:: + + A path to which the `diff` attribute is set is treated + as text, even when they contain byte values that + normally never appear in text files, such as NUL. + +Unset:: + + A path to which the `diff` attribute is unset will + generate `Binary files differ` (or a binary patch, if + binary patches are enabled). + +Unspecified:: + + A path to which the `diff` attribute is unspecified + first gets its contents inspected, and if it looks like + text, it is treated as text. Otherwise it would + generate `Binary files differ`. + +String:: + + Diff is shown using the specified diff driver. Each driver may + specify one or more options, as described in the following + section. The options for the diff driver "foo" are defined + by the configuration variables in the "diff.foo" section of the + git config file. + + +Defining an external diff driver +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The definition of a diff driver is done in `gitconfig`, not +`gitattributes` file, so strictly speaking this manual page is a +wrong place to talk about it. However... + +To define an external diff driver `jcdiff`, add a section to your +`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this: + +---------------------------------------------------------------- +[diff "jcdiff"] + command = j-c-diff +---------------------------------------------------------------- + +When git needs to show you a diff for the path with `diff` +attribute set to `jcdiff`, it calls the command you specified +with the above configuration, i.e. `j-c-diff`, with 7 +parameters, just like `GIT_EXTERNAL_DIFF` program is called. +See linkgit:git[1] for details. + + +Defining a custom hunk-header +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Each group of changes (called a "hunk") in the textual diff output +is prefixed with a line of the form: + + @@ -k,l +n,m @@ TEXT + +This is called a 'hunk header'. The "TEXT" portion is by default a line +that begins with an alphabet, an underscore or a dollar sign; this +matches what GNU 'diff -p' output uses. This default selection however +is not suited for some contents, and you can use a customized pattern +to make a selection. + +First, in .gitattributes, you would assign the `diff` attribute +for paths. + +------------------------ +*.tex diff=tex +------------------------ + +Then, you would define a "diff.tex.xfuncname" configuration to +specify a regular expression that matches a line that you would +want to appear as the hunk header "TEXT". Add a section to your +`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this: + +------------------------ +[diff "tex"] + xfuncname = "^(\\\\(sub)*section\\{.*)$" +------------------------ + +Note. A single level of backslashes are eaten by the +configuration file parser, so you would need to double the +backslashes; the pattern above picks a line that begins with a +backslash, and zero or more occurrences of `sub` followed by +`section` followed by open brace, to the end of line. + +There are a few built-in patterns to make this easier, and `tex` +is one of them, so you do not have to write the above in your +configuration file (you still need to enable this with the +attribute mechanism, via `.gitattributes`). The following built in +patterns are available: + +- `bibtex` suitable for files with BibTeX coded references. + +- `cpp` suitable for source code in the C and C++ languages. + +- `csharp` suitable for source code in the C# language. + +- `fortran` suitable for source code in the Fortran language. + +- `html` suitable for HTML/XHTML documents. + +- `java` suitable for source code in the Java language. + +- `matlab` suitable for source code in the MATLAB language. + +- `objc` suitable for source code in the Objective-C language. + +- `pascal` suitable for source code in the Pascal/Delphi language. + +- `perl` suitable for source code in the Perl language. + +- `php` suitable for source code in the PHP language. + +- `python` suitable for source code in the Python language. + +- `ruby` suitable for source code in the Ruby language. + +- `tex` suitable for source code for LaTeX documents. + + +Customizing word diff +^^^^^^^^^^^^^^^^^^^^^ + +You can customize the rules that `git diff --word-diff` uses to +split words in a line, by specifying an appropriate regular expression +in the "diff.*.wordRegex" configuration variable. For example, in TeX +a backslash followed by a sequence of letters forms a command, but +several such commands can be run together without intervening +whitespace. To separate them, use a regular expression in your +`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this: + +------------------------ +[diff "tex"] + wordRegex = "\\\\[a-zA-Z]+|[{}]|\\\\.|[^\\{}[:space:]]+" +------------------------ + +A built-in pattern is provided for all languages listed in the +previous section. + + +Performing text diffs of binary files +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Sometimes it is desirable to see the diff of a text-converted +version of some binary files. For example, a word processor +document can be converted to an ASCII text representation, and +the diff of the text shown. Even though this conversion loses +some information, the resulting diff is useful for human +viewing (but cannot be applied directly). + +The `textconv` config option is used to define a program for +performing such a conversion. The program should take a single +argument, the name of a file to convert, and produce the +resulting text on stdout. + +For example, to show the diff of the exif information of a +file instead of the binary information (assuming you have the +exif tool installed), add the following section to your +`$GIT_DIR/config` file (or `$HOME/.gitconfig` file): + +------------------------ +[diff "jpg"] + textconv = exif +------------------------ + +NOTE: The text conversion is generally a one-way conversion; +in this example, we lose the actual image contents and focus +just on the text data. This means that diffs generated by +textconv are _not_ suitable for applying. For this reason, +only `git diff` and the `git log` family of commands (i.e., +log, whatchanged, show) will perform text conversion. `git +format-patch` will never generate this output. If you want to +send somebody a text-converted diff of a binary file (e.g., +because it quickly conveys the changes you have made), you +should generate it separately and send it as a comment _in +addition to_ the usual binary diff that you might send. + +Because text conversion can be slow, especially when doing a +large number of them with `git log -p`, git provides a mechanism +to cache the output and use it in future diffs. To enable +caching, set the "cachetextconv" variable in your diff driver's +config. For example: + +------------------------ +[diff "jpg"] + textconv = exif + cachetextconv = true +------------------------ + +This will cache the result of running "exif" on each blob +indefinitely. If you change the textconv config variable for a +diff driver, git will automatically invalidate the cache entries +and re-run the textconv filter. If you want to invalidate the +cache manually (e.g., because your version of "exif" was updated +and now produces better output), you can remove the cache +manually with `git update-ref -d refs/notes/textconv/jpg` (where +"jpg" is the name of the diff driver, as in the example above). + +Choosing textconv versus external diff +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If you want to show differences between binary or specially-formatted +blobs in your repository, you can choose to use either an external diff +command, or to use textconv to convert them to a diff-able text format. +Which method you choose depends on your exact situation. + +The advantage of using an external diff command is flexibility. You are +not bound to find line-oriented changes, nor is it necessary for the +output to resemble unified diff. You are free to locate and report +changes in the most appropriate way for your data format. + +A textconv, by comparison, is much more limiting. You provide a +transformation of the data into a line-oriented text format, and git +uses its regular diff tools to generate the output. There are several +advantages to choosing this method: + +1. Ease of use. It is often much simpler to write a binary to text + transformation than it is to perform your own diff. In many cases, + existing programs can be used as textconv filters (e.g., exif, + odt2txt). + +2. Git diff features. By performing only the transformation step + yourself, you can still utilize many of git's diff features, + including colorization, word-diff, and combined diffs for merges. + +3. Caching. Textconv caching can speed up repeated diffs, such as those + you might trigger by running `git log -p`. + + +Marking files as binary +^^^^^^^^^^^^^^^^^^^^^^^ + +Git usually guesses correctly whether a blob contains text or binary +data by examining the beginning of the contents. However, sometimes you +may want to override its decision, either because a blob contains binary +data later in the file, or because the content, while technically +composed of text characters, is opaque to a human reader. For example, +many postscript files contain only ascii characters, but produce noisy +and meaningless diffs. + +The simplest way to mark a file as binary is to unset the diff +attribute in the `.gitattributes` file: + +------------------------ +*.ps -diff +------------------------ + +This will cause git to generate `Binary files differ` (or a binary +patch, if binary patches are enabled) instead of a regular diff. + +However, one may also want to specify other diff driver attributes. For +example, you might want to use `textconv` to convert postscript files to +an ascii representation for human viewing, but otherwise treat them as +binary files. You cannot specify both `-diff` and `diff=ps` attributes. +The solution is to use the `diff.*.binary` config option: + +------------------------ +[diff "ps"] + textconv = ps2ascii + binary = true +------------------------ + +Performing a three-way merge +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +`merge` +^^^^^^^ + +The attribute `merge` affects how three versions of a file are +merged when a file-level merge is necessary during `git merge`, +and other commands such as `git revert` and `git cherry-pick`. + +Set:: + + Built-in 3-way merge driver is used to merge the + contents in a way similar to 'merge' command of `RCS` + suite. This is suitable for ordinary text files. + +Unset:: + + Take the version from the current branch as the + tentative merge result, and declare that the merge has + conflicts. This is suitable for binary files that do + not have a well-defined merge semantics. + +Unspecified:: + + By default, this uses the same built-in 3-way merge + driver as is the case when the `merge` attribute is set. + However, the `merge.default` configuration variable can name + different merge driver to be used with paths for which the + `merge` attribute is unspecified. + +String:: + + 3-way merge is performed using the specified custom + merge driver. The built-in 3-way merge driver can be + explicitly specified by asking for "text" driver; the + built-in "take the current branch" driver can be + requested with "binary". + + +Built-in merge drivers +^^^^^^^^^^^^^^^^^^^^^^ + +There are a few built-in low-level merge drivers defined that +can be asked for via the `merge` attribute. + +text:: + + Usual 3-way file level merge for text files. Conflicted + regions are marked with conflict markers `<<<<<<<`, + `=======` and `>>>>>>>`. The version from your branch + appears before the `=======` marker, and the version + from the merged branch appears after the `=======` + marker. + +binary:: + + Keep the version from your branch in the work tree, but + leave the path in the conflicted state for the user to + sort out. + +union:: + + Run 3-way file level merge for text files, but take + lines from both versions, instead of leaving conflict + markers. This tends to leave the added lines in the + resulting file in random order and the user should + verify the result. Do not use this if you do not + understand the implications. + + +Defining a custom merge driver +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The definition of a merge driver is done in the `.git/config` +file, not in the `gitattributes` file, so strictly speaking this +manual page is a wrong place to talk about it. However... + +To define a custom merge driver `filfre`, add a section to your +`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this: + +---------------------------------------------------------------- +[merge "filfre"] + name = feel-free merge driver + driver = filfre %O %A %B + recursive = binary +---------------------------------------------------------------- + +The `merge.*.name` variable gives the driver a human-readable +name. + +The `merge.*.driver` variable's value is used to construct a +command to run to merge ancestor's version (`%O`), current +version (`%A`) and the other branches' version (`%B`). These +three tokens are replaced with the names of temporary files that +hold the contents of these versions when the command line is +built. Additionally, %L will be replaced with the conflict marker +size (see below). + +The merge driver is expected to leave the result of the merge in +the file named with `%A` by overwriting it, and exit with zero +status if it managed to merge them cleanly, or non-zero if there +were conflicts. + +The `merge.*.recursive` variable specifies what other merge +driver to use when the merge driver is called for an internal +merge between common ancestors, when there are more than one. +When left unspecified, the driver itself is used for both +internal merge and the final merge. + + +`conflict-marker-size` +^^^^^^^^^^^^^^^^^^^^^^ + +This attribute controls the length of conflict markers left in +the work tree file during a conflicted merge. Only setting to +the value to a positive integer has any meaningful effect. + +For example, this line in `.gitattributes` can be used to tell the merge +machinery to leave much longer (instead of the usual 7-character-long) +conflict markers when merging the file `Documentation/git-merge.txt` +results in a conflict. + +------------------------ +Documentation/git-merge.txt conflict-marker-size=32 +------------------------ + + +Checking whitespace errors +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +`whitespace` +^^^^^^^^^^^^ + +The `core.whitespace` configuration variable allows you to define what +'diff' and 'apply' should consider whitespace errors for all paths in +the project (See linkgit:git-config[1]). This attribute gives you finer +control per path. + +Set:: + + Notice all types of potential whitespace errors known to git. + The tab width is taken from the value of the `core.whitespace` + configuration variable. + +Unset:: + + Do not notice anything as error. + +Unspecified:: + + Use the value of the `core.whitespace` configuration variable to + decide what to notice as error. + +String:: + + Specify a comma separate list of common whitespace problems to + notice in the same format as the `core.whitespace` configuration + variable. + + +Creating an archive +~~~~~~~~~~~~~~~~~~~ + +`export-ignore` +^^^^^^^^^^^^^^^ + +Files and directories with the attribute `export-ignore` won't be added to +archive files. + +`export-subst` +^^^^^^^^^^^^^^ + +If the attribute `export-subst` is set for a file then git will expand +several placeholders when adding this file to an archive. The +expansion depends on the availability of a commit ID, i.e., if +linkgit:git-archive[1] has been given a tree instead of a commit or a +tag then no replacement will be done. The placeholders are the same +as those for the option `--pretty=format:` of linkgit:git-log[1], +except that they need to be wrapped like this: `$Format:PLACEHOLDERS$` +in the file. E.g. the string `$Format:%H$` will be replaced by the +commit hash. + + +Packing objects +~~~~~~~~~~~~~~~ + +`delta` +^^^^^^^ + +Delta compression will not be attempted for blobs for paths with the +attribute `delta` set to false. + + +Viewing files in GUI tools +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +`encoding` +^^^^^^^^^^ + +The value of this attribute specifies the character encoding that should +be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to +display the contents of the relevant file. Note that due to performance +considerations linkgit:gitk[1] does not use this attribute unless you +manually enable per-file encodings in its options. + +If this attribute is not set or has an invalid value, the value of the +`gui.encoding` configuration variable is used instead +(See linkgit:git-config[1]). + + +USING MACRO ATTRIBUTES +---------------------- + +You do not want any end-of-line conversions applied to, nor textual diffs +produced for, any binary file you track. You would need to specify e.g. + +------------ +*.jpg -text -diff +------------ + +but that may become cumbersome, when you have many attributes. Using +macro attributes, you can define an attribute that, when set, also +sets or unsets a number of other attributes at the same time. The +system knows a built-in macro attribute, `binary`: + +------------ +*.jpg binary +------------ + +Setting the "binary" attribute also unsets the "text" and "diff" +attributes as above. Note that macro attributes can only be "Set", +though setting one might have the effect of setting or unsetting other +attributes or even returning other attributes to the "Unspecified" +state. + + +DEFINING MACRO ATTRIBUTES +------------------------- + +Custom macro attributes can be defined only in the `.gitattributes` +file at the toplevel (i.e. not in any subdirectory). The built-in +macro attribute "binary" is equivalent to: + +------------ +[attr]binary -diff -text +------------ + + +EXAMPLE +------- + +If you have these three `gitattributes` file: + +---------------------------------------------------------------- +(in $GIT_DIR/info/attributes) + +a* foo !bar -baz + +(in .gitattributes) +abc foo bar baz + +(in t/.gitattributes) +ab* merge=filfre +abc -foo -bar +*.c frotz +---------------------------------------------------------------- + +the attributes given to path `t/abc` are computed as follows: + +1. By examining `t/.gitattributes` (which is in the same + directory as the path in question), git finds that the first + line matches. `merge` attribute is set. It also finds that + the second line matches, and attributes `foo` and `bar` + are unset. + +2. Then it examines `.gitattributes` (which is in the parent + directory), and finds that the first line matches, but + `t/.gitattributes` file already decided how `merge`, `foo` + and `bar` attributes should be given to this path, so it + leaves `foo` and `bar` unset. Attribute `baz` is set. + +3. Finally it examines `$GIT_DIR/info/attributes`. This file + is used to override the in-tree settings. The first line is + a match, and `foo` is set, `bar` is reverted to unspecified + state, and `baz` is unset. + +As the result, the attributes assignment to `t/abc` becomes: + +---------------------------------------------------------------- +foo set to true +bar unspecified +baz set to false +merge set to string value "filfre" +frotz unspecified +---------------------------------------------------------------- + + +SEE ALSO +-------- +linkgit:git-check-attr[1]. + +GIT +--- +Part of the linkgit:git[1] suite |