GITATTRIBUTES(5)

🌸 NAME 🌸

okay so bestie, this is gitattributes(5) from the Git Manual — literally gitattributes - Defining attributes per path. It's giving "tiny text file, massive control over how Git treats your files." 💅

✨ SYNOPSIS ✨

$GIT_DIR/info/attributes, .gitattributes

🎀 DESCRIPTION 🎀

A gitattributes file is a simple text file that gives attributes to pathnames. No cap, that's the whole vibe. 🫶

Each line in a gitattributes file is of this form:

pattern attr1 attr2 ...

That is, a pattern followed by an attributes list, separated by whitespaces. Leading and trailing whitespaces are ignored. Lines that begin with # are ignored. Patterns that begin with a double quote are quoted in C style. When the pattern matches the path in question, the attributes listed on the line are given to the path. periodt. ✨

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. Stacked rules? Later one wins. Iconic behavior tbh. 👑

The rules by which the pattern matches paths are the same as in .gitignore files (see gitignore(5)), with a few exceptions:

negative patterns are forbidden
patterns that match a directory do not recursively match paths inside that directory (so using the trailing-slash path/ syntax is pointless in an attributes file; use path/** instead)

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). Precedence drama, but make it organized. 💅

When the .gitattributes file is missing from the work tree, the path in the index is used as a fall-back. During checkout process, .gitattributes in the index is used and then the file in the working tree is used as a fall-back. Fallback queen behavior. 🦋

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 git-config(1)). Its default value is $XDG_CONFIG_HOME/git/attributes. If $XDG_CONFIG_HOME is either not set or empty, $HOME/.config/git/attributes is used instead. Attributes for all users on a system should be placed in the $(prefix)/etc/gitattributes file. 🌈

Sometimes you would need to override a 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 !. boom, unspecified, bye. 💀

🛡️ RESERVED BUILTIN_* ATTRIBUTES 🛡️

builtin_* is a reserved namespace for builtin attribute values. Any user defined attributes under this namespace will be ignored and trigger a warning. do not touch, bestie, it's reserved. 🚫

🔍 builtin_objectmode

This attribute is for filtering files by their file bit modes (40000, 120000, 160000, 100755, 100644). e.g. :(attr:builtin_objectmode=160000). You may also check these values with git check-attr builtin_objectmode -- <file>. If the object is not in the index git check-attr --cached will return unspecified. mode check, slay. ✨

💥 EFFECTS 💥

Certain operations by Git can be influenced by assigning particular attributes to a path. Currently, the following operations are attributes-aware. aka: attributes are lowkey main character energy in Git. 👑

📦 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 switch, 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 marks the path as a text file, which enables end-of-line conversion: When a matching file is added to the index, the file’s line endings are normalized to LF in the index. Conversely, when the file is copied from the index to the working directory, its line endings may be converted from LF to CRLF depending on the eol attribute, the Git config, and the platform (see explanation of eol below). line endings are literally getting a glow-up. ✨

Set — Setting the text attribute on a path enables end-of-line conversion on checkin and checkout as described above. Line endings are normalized to LF in the index every time the file is checked in, even if the file was previously added to Git with CRLF line endings.
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", Git decides by itself whether the file is text or binary. If it is text and the file was not already in Git with CRLF endings, line endings are converted on checkin and checkout as described above. Otherwise, no conversion is done on checkin or checkout.
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. unspecified-ish, but make it Git. 👀

🌊 eol

This attribute marks a path to use a specific line-ending style in the working tree when it is checked out. It has effect only if text or text=auto is set (see above), but specifying eol automatically sets text if text was left unspecified. automatic text setting? she's efficient. 💅

Set to string value "crlf" — This setting converts the file’s line endings in the working directory to CRLF when the file is checked out.
Set to string value "lf" — This setting uses the same line endings in the working directory as in the index when the file is checked out.
Unspecified — If the eol attribute is unspecified for a file, its line endings in the working directory are determined by the core.autocrlf or core.eol configuration variable (see the definitions of those options in git-config(1)). If text is set but neither of those variables is, the default is eol=crlf on Windows and eol=lf on all other platforms.

🔁 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. normalize, optionally convert, stay cute. ✨

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 using any attributes.

[core]
    autocrlf = true

This does not force normalization of 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 ensure that text files that any contributor introduces to the repository have their line endings normalized, you can set the text attribute to "auto" for all files.

*       text=auto

The attributes allow a fine-grained control, how the line endings are converted. 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.

*               text=auto
*.txt           text
*.vcproj        text eol=crlf
*.sh            text eol=lf
*.jpg           -text

Note — When text=auto conversion is enabled in a cross-platform project using push and pull to a central repository the text files containing CRLFs should be normalized.

From a clean working directory:

$ echo "* text=auto" >.gitattributes
$ git add --renormalize .
$ git status        # Show files that will be normalized
$ 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.

🧬 working-tree-encoding 🧬

So here's the tea ☕: Git recognizes files encoded in ASCII or one of its supersets (like UTF-8, ISO-8859-1, ...) as text files. But files encoded in certain other encodings (like UTF-16) get read as binary, and consequently the built-in Git text processing tools (like git diff) plus most Git web front ends just do not visualize the contents of those files by default. 😭

That's where the working-tree-encoding attribute comes in, bestie. You use it to tell Git the encoding of a file in the working directory. If a file with this attribute gets added to Git, Git re-encodes the content from the encoding you specified to UTF-8. Then Git stores that UTF-8 encoded content in its internal data structure (called "the index"). On checkout, the content gets re-encoded back to the encoding you specified. Slay. ✨

But please note, using the working-tree-encoding attribute may have a number of pitfalls:

Alternative Git implementations (like JGit or libgit2) and older Git versions (as of March 2018) do not support the working-tree-encoding attribute. If you decide to use the working-tree-encoding attribute in your repository, then it is strongly recommended to ensure that all clients working with the repository support it.
- For example, Microsoft Visual Studio resources files (*.rc) or PowerShell script files (*.ps1) are sometimes encoded in UTF-16. If you declare *.ps1 as files as UTF-16 and you add foo.ps1 with a working-tree-encoding enabled Git client, then foo.ps1 will be stored as UTF-8 internally. A client without working-tree-encoding support will checkout foo.ps1 as a UTF-8 encoded file. This will typically cause trouble for the users of this file. 💀
- If a Git client that does not support the working-tree-encoding attribute adds a new file bar.ps1, then bar.ps1 will be stored "as-is" internally (in this example probably as UTF-16). A client with working-tree-encoding support will interpret the internal contents as UTF-8 and try to convert it to UTF-16 on checkout. That operation will fail and cause an error. 🙈
Reencoding content to non-UTF encodings can cause errors as the conversion might not be UTF-8 round trip safe. If you suspect your encoding to not be round trip safe, then add it to core.checkRoundtripEncoding to make Git check the round trip encoding (see git-config(1)). SHIFT-JIS (Japanese character set) is known to have round trip issues with UTF-8 and is checked by default.
Reencoding content requires resources that might slow down certain Git operations (like git checkout or git add).

Use the working-tree-encoding attribute only if you cannot store a file in UTF-8 encoding and if you want Git to be able to process the content as text.

As an example, use the following attributes if your *.ps1 files are UTF-16 encoded with byte order mark (BOM) and you want Git to perform automatic line ending conversion based on your platform.

*.ps1           text working-tree-encoding=UTF-16

Use the following attributes if your *.ps1 files are UTF-16 little endian encoded without BOM and you want Git to use Windows line endings in the working directory (use UTF-16LE-BOM instead of UTF-16LE if you want UTF-16 little endian with BOM). Please note, it is highly recommended to explicitly define the line endings with eol if the working-tree-encoding attribute is used to avoid ambiguity. 🎀

*.ps1           text working-tree-encoding=UTF-16LE eol=crlf

You can get a list of all available encodings on your platform with the following command:

iconv --list

If you do not know the encoding of a file, then you can use the file command to guess the encoding:

file foo.ps1

💅 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. It's giving keyword-substitution main character energy, honestly. 👑

🦋 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 the worktree file upon checkin. By default these commands process only a single blob and terminate. But if a long running process filter is used in place of clean and/or smudge filters, then Git can process all the blobs with a single filter command invocation for the entire life of a single Git command — git add --all, for example. If a long running process filter is configured then it always takes precedence over a configured single blob filter. (The section below has the full description of the protocol used to communicate with a process filter, iykyk.)

One use of the content filtering is to massage the content into a shape that is more convenient for the platform, filesystem, and the user to use. For this mode of operation, 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. 💅

Another use of the content filtering is to store the content that cannot be directly used in the repository (like a UUID that refers to the true content stored outside Git, or an encrypted content) and turn it into a usable form upon checkout (like download the external content, or decrypt the encrypted content).

These two filters behave differently, and by default, a filter is taken as the former — massaging the contents into a more convenient shape. A missing filter driver definition in the config, or a filter driver that exits with a non-zero status, is not an error but makes the filter a no-op passthru.

You can declare that a filter turns content that by itself is unusable into usable content by setting the filter.<driver>.required configuration variable to true.

Note: whenever the clean filter is changed, the repo should be renormalized: $ git add --renormalize .

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.

If a filter must succeed in order to make the stored contents usable, you can declare that the filter is required, in the configuration:

[filter "crypt"]
        clean = openssl enc ...
        smudge = openssl enc -d ...
        required

The 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

Note that "%f" is the name of the path that is being worked on. Depending on the version that is being filtered, the corresponding file on disk may not exist, or may have different contents. So, smudge and clean commands should not try to access the file on disk — they only act as filters on the content provided to them on standard input. 🙅‍♀️

🌈 Long Running Filter Process 🌈

If the filter command (a string value) is defined via filter.<driver>.process then Git can process all blobs with a single filter invocation for the entire life of a single Git command. This is achieved by using the long-running process protocol (described in Documentation/technical/long-running-process-protocol.adoc).

When Git encounters the first file that needs to be cleaned or smudged, it starts the filter and performs the handshake. In the handshake, the welcome message sent by Git is "git-filter-client", only version 2 is supported, and the supported capabilities are "clean", "smudge", and "delay".

Afterwards Git sends a list of "key=value" pairs terminated with a flush packet. The list will contain at least the filter command (based on the supported capabilities) and the pathname of the file to filter relative to the repository root. Right after the flush packet Git sends the content split in zero or more pkt-line packets and a flush packet to terminate content. Please note, that the filter must not send any response before it received the content and the final flush packet. Also note that the "value" of a "key=value" pair can contain the "=" character whereas the key would never contain that character. 🫶

packet:          git> command=smudge
packet:          git> pathname=path/testfile.dat
packet:          git> 0000
packet:          git> CONTENT
packet:          git> 0000

okay so the filter is supposed to clap back with a list of key=value pairs, and that list is terminated with a flush packet. If the filter is having zero problems, then the list must contain a success status. Right after those packets, the filter is expected to send the content in zero or more pkt-line packets and a flush packet at the end. Finally, a second list of key=value pairs terminated with a flush packet is expected. The filter can change the status in the second list or keep the status as is with an empty list. Please note that the empty list must be terminated with a flush packet regardless. 💅

packet:          git< status=success
packet:          git< 0000
packet:          git< SMUDGED_CONTENT
packet:          git< 0000
packet:          git< 0000  # empty list, keep "status=success" unchanged!

If the result content is empty, then the filter is expected to respond with a success status and a flush packet to signal the empty content. Not me forgetting the flush packet — couldn’t be me. 😭

packet:          git< status=success
packet:          git< 0000
packet:          git< 0000  # empty content!
packet:          git< 0000  # empty list, keep "status=success" unchanged!

In case the filter cannot or does not want to process the content, it is expected to respond with an error status. respect the boundary, bestie 🫶

packet:          git< status=error
packet:          git< 0000

If the filter experiences an error during processing, then it can send the status error after the content was (partially or completely) sent. messy, but valid 💀

packet:          git< status=success
packet:          git< 0000
packet:          git< HALF_WRITTEN_ERRONEOUS_CONTENT
packet:          git< 0000
packet:          git< status=error
packet:          git< 0000

In case the filter cannot or does not want to process the content as well as any future content for the lifetime of the Git process, then it is expected to respond with an abort status at any point in the protocol. it’s giving “I’m done here” energy, and honestly? iconic. 👑

packet:          git< status=abort
packet:          git< 0000

Git neither stops nor restarts the filter process in case the error/abort status is set. However, Git sets its exit code according to the filter.<driver>.required flag, mimicking the behavior of the filter.<driver>.clean / filter.<driver>.smudge mechanism. so the exit code still has main character energy, even when the filter is being dramatic. ✨

If the filter dies during the communication or does not adhere to the protocol, then Git will stop the filter process and restart it with the next file that needs to be processed. Depending on the filter.<driver>.required flag Git will interpret that as error. vibe check failed → Git moves on with its life. 🦋

⏳ Delay

If the filter supports the delay capability, then Git can send the flag can-delay after the filter command and pathname. This flag denotes that the filter can delay filtering the current blob (e.g. to compensate network latencies) by responding with no content but with the status delayed and a flush packet. lowkey a little “brb” moment. 🌸

packet:          git> command=smudge
packet:          git> pathname=path/testfile.dat
packet:          git> can-delay=1
packet:          git> 0000
packet:          git> CONTENT
packet:          git> 0000
packet:          git< status=delayed
packet:          git< 0000

If the filter supports the delay capability then it must support the list_available_blobs command. If Git sends this command, then the filter is expected to return a list of pathnames representing blobs that have been delayed earlier and are now available. The list must be terminated with a flush packet followed by a success status that is also terminated with a flush packet. If no blobs for the delayed paths are available, yet, then the filter is expected to block the response until at least one blob becomes available. The filter can tell Git that it has no more delayed blobs by sending an empty list. As soon as the filter responds with an empty list, Git stops asking. All blobs that Git has not received at this point are considered missing and will result in an error. no cap, missing blobs are a whole situation. 😭

packet:          git> command=list_available_blobs
packet:          git> 0000
packet:          git< pathname=path/testfile.dat
packet:          git< pathname=path/otherfile.dat
packet:          git< 0000
packet:          git< status=success
packet:          git< 0000

After Git received the pathnames, it will request the corresponding blobs again. These requests contain a pathname and an empty content section. The filter is expected to respond with the smudged content in the usual way as explained above. round two, but make it smudged. 🌀

packet:          git> command=smudge
packet:          git> pathname=path/testfile.dat
packet:          git> 0000
packet:          git> 0000  # empty content!
packet:          git< status=success
packet:          git< 0000
packet:          git< SMUDGED_CONTENT
packet:          git< 0000
packet:          git< 0000  # empty list, keep "status=success" unchanged!

🧪 Example

A long running filter demo implementation can be found in contrib/long-running-filter/example.pl located in the Git core repository. If you develop your own long running filter process then the GIT_TRACE_PACKET environment variables can be very helpful for debugging (see git(1)). debugging fuel, fr fr. 🔥

Please note that you cannot use an existing filter.<driver>.clean or filter.<driver>.smudge command with filter.<driver>.process because the former two use a different inter process communication protocol than the latter one. different protocol, different era. periodt. 💅

🔁 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). pipeline order matters, bestie — do not shuffle it. 🎀

In the check-out codepath, the blob content is first converted with text, and then ident and fed to filter. same energy, opposite direction. 🦋

🧬 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. the drama. 💀

To prevent these unnecessary merge conflicts, Git can be told to run a virtual check-out and check-in of all three stages of each file that needs a three-way content 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. virtual check-in? she’s organized. ✨

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. manual conflict resolution is not the vibe, but sometimes it’s the assignment. 😭

💅 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. diff customization is highkey a superpower. 👑

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 and is smaller than core.bigFileThreshold, 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 git(1) for details. seven parameters, no notes. 🎀

If the program is able to ignore certain changes (similar to git diff --ignore-space-change), then also set the option trustExitCode to true. It is then expected to return exit code 1 if it finds significant changes and 0 if it doesn’t. trust the exit code, but only when you mean it. 🫶

🧠 Setting the internal diff algorithm

The diff algorithm can be set through the diff.algorithm config key, but sometimes it may be helpful to set the diff algorithm per path. For example, one may want to use the minimal diff algorithm for .json files, and the histogram for .c files, and so on without having to pass in the algorithm through the command line each time. per-path algorithm choices are lowkey gourmet. 🍓

First, in .gitattributes, assign the diff attribute for paths.

*.json diff=<name>

Then, define a diff.<name>.algorithm configuration to specify the diff algorithm, choosing from myers, patience, minimal, or histogram.

[diff "<name>"]
  algorithm = histogram

This diff algorithm applies to user facing diff output like git-diff(1), git-show(1) and is used for the --stat output as well. The merge machinery will not use the diff algorithm set through this method. user-facing slay only; merge machinery is on its own path. 💅

📝 Note

Okay so if diff.<name>.command is defined for a path with the diff=<name> attribute, it is executed as an external diff driver (see above), and adding diff.<name>.algorithm has no effect, because the algorithm is not passed to the external diff driver. That’s just how it is, bestie. 💅

✨ 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:

ada — suitable for source code in the Ada language.
bash — suitable for source code in the Bourne-Again SHell language. Covers a superset of POSIX shell function definitions.
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.
css — suitable for cascading style sheets.
dts — suitable for devicetree (DTS) files.
elixir — suitable for source code in the Elixir language.
fortran — suitable for source code in the Fortran language.
fountain — suitable for Fountain documents.
golang — suitable for source code in the Go language.
html — suitable for HTML/XHTML documents.
java — suitable for source code in the Java language.
kotlin — suitable for source code in the Kotlin language.
markdown — suitable for Markdown documents.
matlab — suitable for source code in the MATLAB and Octave languages.
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.
rust — suitable for source code in the Rust language.
scheme — suitable for source code in most Lisp dialects, including Scheme, Emacs Lisp, Common Lisp, and Clojure.
swift — suitable for source code in the Swift 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:

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).
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.
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 — okay so with this value, the 3-way merge runs through the custom merge driver you picked. You can explicitly ask for the built-in 3-way merge driver by requesting the "text" driver, and the built-in “take the current branch” driver by asking for "binary". 💅

✨ Built-in merge drivers ✨

There are a few built-in low-level merge drivers you can request via the merge attribute:

text — the usual 3-way file-level merge for text files. Conflicted regions get marked with <<<<<<<, =======, and >>>>>>>. The version from your branch shows up before the ======= marker, and the version from the merged branch shows up after it.
binary — keep the version from your branch in the work tree, but leave the path in the conflicted state so the user can sort it out.
union — run a 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. Fr fr, it’s giving “chaos with a bow on top” 💀

🛠️ Defining a custom merge driver 🛠️

The definition of a merge driver happens 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 %L %P
        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 against the common ancestor’s version (%O), the current version (%A), and the other branch’s version (%B). These three tokens get replaced with the names of temporary files that hold the contents of those 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. When the driver crashes (e.g. killed by SEGV), it is expected to exit with non-zero status that are higher than 128, and in such a case, the merge results in a failure — which is different from producing a conflict.

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 is more than one. When left unspecified, the driver itself is used for both the internal merge and the final merge.

The merge driver can learn the pathname in which the merged result will be stored via placeholder %P. The conflict labels to be used for the common ancestor, local head, and other head can be passed by using %S, %X, and %Y respectively.

🎀 conflict-marker-size 🎀

This attribute controls the length of conflict markers left in the work tree file during a conflicted merge. Only a positive integer has a 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.adoc results in a conflict:

Documentation/git-merge.adoc    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 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-separated 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 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. However, only one %(describe) placeholder is expanded per archive to avoid denial-of-service attacks.

🗜️ 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. 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)).

🌈 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 top-level gitattributes files ($GIT_DIR/info/attributes, the .gitattributes file at the top level of the working tree, or the global or system-wide gitattributes files), not in .gitattributes files in working tree subdirectories. The built-in macro attribute "binary" is equivalent to:

[attr]binary -diff -merge -text

📝 NOTES 📝

Git does not follow symbolic links when accessing a .gitattributes file in the working tree. This keeps behavior consistent when the file is accessed from the index or a tree versus from the filesystem.

💖 EXAMPLES 💖

If you have these three gitattributes files:

(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:

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.
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.
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 👀

git-check-attr(1).

🏁 GIT 🏁

Part of the git(1) suite.

💖 That’s the whole page, bestie — straight from Git 2.56.0, dated 2026-09-27. Now go forth and slay those attributes 💅✨

📦 where this page comes from

arch rolling: git 2.56.0-1 · GPL-2.0-only
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-06: a language model's rewrite of the original, under its terms