gitattributes - Defining attributes per path
$GIT_DIR/info/attributes, .gitattributes
A
gitattributes file is a simple text file that gives
attributes
to pathnames.
Each line in
gitattributes file is of form:
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
!.
Certain operations by Git can be influenced by assigning particular attributes
to a path. Currently, the following operations are attributes-aware.
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 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 setting
core.autocrlf to
true or
input overrides
core.eol (see the definitions of
those options in
git-config(1)).
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. This attribute has effect only if the
text attribute is set
or unspecified, or if it is set to
auto, the file is detected as text,
and it is stored with LF endings in the index. Note that setting this
attribute on paths which are in the index with CRLF line endings may make the
paths to be considered dirty unless
text=auto is set. 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.
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
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.
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...
•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
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:
•Alternative Git implementations (e.g.
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 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 (e.g 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:
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.
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:
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:
•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 the Scheme 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:
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.
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
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.
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)).
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.
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:
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.
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
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.
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
git-check-attr(1).
Part of the
git(1) suite