Provided by:
git-core_1.5.4.3-1ubuntu2_i386 
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:
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).
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.
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