GITATTRIBUTES(5) Git Manual GITATTRIBUTES(5)NAMEgitattributes - defining attributes per path
SYNOPSIS
$GIT_DIR/info/attributes, gitattributesDESCRIPTION
A gitattributes file is a simple text file that gives attributes to
pathnames.
Each line in gitattributes file is of form:
glob attr1 attr2 ...
That is, a glob pattern followed by an attributes list, separated by
whitespaces. When the glob 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 glob 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 glob pattern matches the path, a later line
overrides an earlier line. This overriding is done per
attribute.
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 (the further the
directory that contains .gitattributes is from the path in
question, the lower its precedence).
If you wish to affect only a single repository (i.e., to assign
attributes to files that are particular to one user's workflow),
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.
Sometimes you would need to override an 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.
crlf
This attribute controls the line-ending convention.
Set Setting the crlf attribute on a path is meant to mark the
path as a "text" file. core.autocrlf conversion takes place
without guessing the content type by inspection.
Unset Unsetting the crlf attribute on a path is meant to mark the
path as a "binary" file. The path never goes through line
endings conversion upon checkin/checkout.
Unspecified
Unspecified crlf attribute tells git to apply the
core.autocrlf conversion when the file content looks like
text.
Set to string value "input"
This is similar to setting the attribute to true, but also
forces git to act as if core.autocrlf is set to input for the
path.
Any other value set to crlf attribute is ignored and git acts
as if the attribute is left unspecified.
The core.autocrlf conversion
If the configuration variable core.autocrlf is false, no conversion
is done.
When core.autocrlf is true, it means that the platform wants CRLF
line endings for files in the working tree, and you want to convert
them back to the normal LF line endings when checking in to the
repository.
When core.autocrlf is set to "input", line endings are converted to
LF upon checkin, but there is no conversion done upon checkout.
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 to a path, git replaces $Id$ in the
blob object with $Id:, followed by 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.
A missing filter driver definition in the config is not an error but
makes the filter a no-op passthru.
The content filtering is done to massage the content into a shape
that is more convenient for the platform, filesystem, and the user
to use. The key phrase here is "more convenient" and not "turning
something unusable into usable". In other words, the intent is that
if someone unsets the filter driver definition, or does not have the
appropriate filter program, the project should still be usable.
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 crlf (again, if specified and applicable).
In the check-out codepath, the blob content is first converted with
crlf, and then ident and fed to filter.
Generating diff text
The attribute diff affects if git diff generates textual patch for the
path or just says Binary files differ. It also can affect what line is
shown on the hunk header @@ -k,l +n,m @@ line.
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.
Unspecified
A path to which the diff attribute is unspecified first gets its
contents inspected, and if it looks like text, it is treated as
text. Otherwise it would generate Binary files differ.
String Diff is shown using the specified custom diff driver. The driver
program is given its input using the same calling convention as
used for GIT_EXTERNAL_DIFF program. This name is also used for
custom hunk header selection.
Defining a custom 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 a custom diff driver jcdiff, add a section to your
$GIT_DIR/config file (or $HOME/.gitconfig file) like this:
[diff "jcdiff"]
command = j-c-diff
When git needs to show you a diff for the path with diff attribute
set to jcdiff, it calls the command you specified with the above
configuration, i.e. j-c-diff, with 7 parameters, just like
GIT_EXTERNAL_DIFF program is called. See git(7) for details.
Defining a custom hunk-header
Each group of changes (called "hunk") in the textual diff output is
prefixed with a line of the form:
@@ -k,l +n,m @@ TEXT
The text is called hunk header, and by default a line that begins
with an alphabet, an underscore or a dollar sign is used, which
matches what GNU diff -p output uses. This default selection however
is not suited for some contents, and you can use customized pattern
to make a selection.
First in .gitattributes, you would assign the diff attribute for
paths.
*.tex diff=tex
Then, you would define "diff.tex.funcname" configuration to specify
a regular expression that matches a line that you would want to
appear as the hunk header, like this:
[diff "tex"]
funcname = "^\\(\\\\\\(sub\\)*section{.*\\)$"
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). Another built-in pattern is defined
for java that defines a pattern suitable for program text in Java
language.
Performing a three-way merge
The attribute merge affects how three versions of a file is merged when
a file-level merge is necessary during git merge, and other programs
such as git revert and git cherry-pick.
Set Built-in 3-way merge driver is used to merge the contents in a
way similar to merge command of RCS suite. This is suitable for
ordinary text files.
Unset Take the version from the current branch as the tentative merge
result, and declare that the merge has conflicts. This is
suitable for binary files that does not have a well-defined
merge semantics.
Unspecified
By default, this uses the same built-in 3-way merge driver as is
the case the merge attribute is set. However, merge.default
configuration variable can name different merge driver to be
used for paths to which the merge attribute is unspecified.
String 3-way merge is performed using the specified custom merge
driver. The built-in 3-way merge driver can be explicitly
specified by asking for "text" driver; the built-in "take the
current branch" driver can be requested with "binary".
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
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.
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.
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.
Unset Do not notice anything as error.
Unspecified
Use the value of core.whitespace configuration variable to
decide what to notice as error.
String Specify a comma separate list of common whitespace problems
to notice in the same format as core.whitespace configuration
variable.
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
Creating an archive
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.
GIT
Part of the git(7) suite
Git 1.5.5.2 10/21/2008 GITATTRIBUTES(5)
