Man page 5 : gitattributes

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.

.it 1 an-trap
.ps +1 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.

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.ps +1 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.

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.ps +1 Backwards compatibility with crlf attribute
    

For backwards compatibility, the crlf attribute is interpreted as follows:


    .

crlf            text
-crlf           -text
crlf=input      eol=lf

.



.it 1 an-trap
.ps +1 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.

.
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.ps +1 Note .ps -1


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...


    .ie n \ \h'-04'\h'+03'\c .

2.3 . git add itself does not touch the files in the work tree, the next checkout would, so the safety triggers;


    .ie n \ \h'-04'\h'+03'\c .

2.3 . 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;


    .ie n \ \h'-04'\h'+03'\c .

2.3 . 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.

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.ps +1 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.

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.ps +1 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

.



.it 1 an-trap
.ps +1 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.

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.ps +1 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.

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.ps +1 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 git(1) for details.

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.ps +1 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:


    .ie n \ \h'-04'\h'+03'\c .

2.3 . bibtex suitable for files with BibTeX coded references.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . cpp suitable for source code in the C and C++ languages.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . html suitable for HTML/XHTML documents.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . java suitable for source code in the Java language.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . objc suitable for source code in the Objective-C language.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . pascal suitable for source code in the Pascal/Delphi language.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . php suitable for source code in the PHP language.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . python suitable for source code in the Python language.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . ruby suitable for source code in the Ruby language.


    .ie n \ \h'-04'\h'+03'\c .

2.3 . tex suitable for source code for LaTeX documents.

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.ps +1 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.

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.ps +1 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

.



.
    .it 1 an-trap
.ps +1 Note .ps -1


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(cqs 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).

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.ps +1 merge
    

The attribute merge affects how three versions of a file is 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 does not have a well-defined merge semantics.

Unspecified
    By default, this uses the same built-in 3-way merge driver as is the case the merge attribute is set. However, merge.default configuration variable can name different merge driver to be used for paths to 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".

.it 1 an-trap
.ps +1 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.

.it 1 an-trap
.ps +1 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 (oqmerge.*.driver` variable(cqs value is used to construct a command to run to merge ancestor(cqs version (%O), current version (%A) and the other branches(cq 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.

.it 1 an-trap
.ps +1 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

.

.it 1 an-trap
.ps +1 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 git-config(1)). This attribute gives you finer control per path.

Set
    Notice all types of potential whitespace errors known to git.

Unset
    Do not notice anything as error.

Unspecified
    Use the value of 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 core.whitespace configuration variable.

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.ps +1 export-ignore
    

Files and directories with the attribute export-ignore won(cqt be added to archive files.

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.ps +1 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 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 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.

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.ps +1 delta
    

Delta compression will not be attempted for blobs for paths with the attribute delta set to false.

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.ps +1 encoding
    

The value of this attribute specifies the character encoding that should be used by GUI tools (e.g. gitk(1) and git-gui(1)) to display the contents of the relevant file. Note that due to performance considerations 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 git-config(1)).