Do not use windows line endings

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).

Any other value causes Git to act as if text has been left
unspecified.

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.

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.

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.

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

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.

Conversely, text files that Git does not detect can have normalization
enabled manually.

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…​

working-tree-encoding

Git recognizes files encoded in ASCII or one of its supersets (e.g.
UTF-8, ISO-8859-1, …​) as text files. Files encoded in certain other
encodings (e.g. UTF-16) are interpreted as binary and consequently
built-in Git text processing tools (e.g. git diff) as well as most Git
web front ends do not visualize the contents of these files by default.

In these cases you can tell Git the encoding of a file in the working
directory with the working-tree-encoding attribute. If a file with this
attribute is added to Git, then Git re-encodes the content from the
specified encoding to UTF-8. Finally, Git stores the UTF-8 encoded
content in its internal data structure (called «the index»). On checkout
the content is re-encoded back to the specified encoding.

Please note that using the working-tree-encoding attribute may have a
number of pitfalls:

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:

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

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.

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
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

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.

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.

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.

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.

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

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.

Each group of changes (called a «hunk») in the textual diff output
is prefixed with a line of the form:

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.

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:

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

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:

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:

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

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.

Built-in merge drivers

There are a few built-in low-level merge drivers defined that
can be asked for via the merge attribute.

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. 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 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

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.

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.

delta

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

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]).