bionic (5) gitattributes.5.gz

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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. 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.

       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 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).

       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.

       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 !.

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. Note that core.autocrlf overrides core.eol

           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 conversion. If Git
               decides that the content is text, its line endings are converted to LF on checkin. When the file
               has been committed with CRLF, no conversion is done.

           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 conversion without any content checks, effectively setting the text attribute. Note that
           setting this attribute on paths which are in the index with CRLF line endings may make the paths to
           be considered dirty. Adding the path to the index again will normalize the line endings in the index.

           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.

           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.

       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. By default these
           commands process only a single blob and terminate. If a long running process filter is used in place
           of clean and/or smudge filters, then Git can process all blobs with a single filter command
           invocation for the entire life of a single Git command, for example git add --all. If a long running
           process filter is configured then it always takes precedence over a configured single blob filter.
           See section below for the description of the protocol used to communicate with a process filter.

           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 (e.g. a UUID that refers to the true content stored outside Git, or an encrypted content)
           and turn it into a usable form upon checkout (e.g. 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 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 a content that by itself is unusable into a 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

           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, but 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
           technical/long-running-process-protocol.txt).

           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 suppported, 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

           The filter is expected to respond with a list of "key=value" pairs terminated with a flush packet. If
           the filter does not experience problems then the list must contain a "success" status. Right after
           these 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.

               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.

               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.

               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.

               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.

           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.

       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.

               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.

               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.

               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)).

           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.

       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 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.

       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.

           •   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.

           •   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.

           •   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 %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 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.

           The merge driver can learn the pathname in which the merged result will be stored via placeholder %P.

       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 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 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.

   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

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

       git-check-attr(1).

GIT

       Part of the git(1) suite