`ident`
^^^^^^^
-When the attribute `ident` is set to a path, git replaces
-`$Id$` in the blob object with `$Id:`, followed by
+When the attribute `ident` is set for a path, git replaces
+`$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 `$` in the worktree file is replaced
Generating diff text
~~~~~~~~~~~~~~~~~~~~
-The attribute `diff` affects if 'git-diff' generates textual
-patch for the path or just says `Binary files differ`. It also
-can affect what line is shown on the hunk header `@@ -k,l +n,m @@`
-line.
+`diff`
+^^^^^^
+
+The attribute `diff` affects how 'git' generates diffs for particular
+files. It can tell git whether to generate a textual patch for the path
+or to treat the path as a binary file. It can also affect what line is
+shown on the hunk header `@@ -k,l +n,m @@` line, tell git to use an
+external command to generate the diff, or ask git to convert binary
+files to a text format before generating the diff.
Set::
Unset::
A path to which the `diff` attribute is unset will
- generate `Binary files differ`.
+ generate `Binary files differ` (or a binary patch, if
+ binary patches are enabled).
Unspecified::
String::
- Diff is shown using the specified custom diff driver.
- The driver program is given its input using the same
- calling convention as used for GIT_EXTERNAL_DIFF
- program. This name is also used for custom hunk header
- selection.
+ Diff is shown using the specified diff driver. Each driver may
+ specify one or more options, as described in the following
+ section. The options for the diff driver "foo" are defined
+ by the configuration variables in the "diff.foo" section of the
+ git config file.
-Defining a custom diff driver
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Defining an external diff driver
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The definition of a diff driver is done in `gitconfig`, not
`gitattributes` file, so strictly speaking this manual page is a
wrong place to talk about it. However...
-To define a custom diff driver `jcdiff`, add a section to your
+To define an external diff driver `jcdiff`, add a section to your
`$GIT_DIR/config` file (or `$HOME/.gitconfig` file) like this:
----------------------------------------------------------------
- `tex` suitable for source code for LaTeX documents.
+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):
+
+------------------------
+[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.
+
+
Performing a three-way merge
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+`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`.
commit hash.
+Viewing files in GUI tools
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+`encoding`
+^^^^^^^^^^
+
+The value of this attribute specifies the character encoding that should
+be used by GUI tools (e.g. linkgit:gitk[1] and linkgit:git-gui[1]) to
+display the contents of the relevant file. Note that due to performance
+considerations linkgit: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 linkgit:git-config[1]).
+
+
USING ATTRIBUTE MACROS
----------------------