-The output format from "git-diff-index", "git-diff-tree" and
-"git-diff-files" are very similar.
+Raw output format
+-----------------
-These commands all compare two sets of things; what is
+The raw output format from "git-diff-index", "git-diff-tree",
+"git-diff-files" and "git diff --raw" are very similar.
+
+These commands all compare two sets of things; what is
compared differs:
git-diff-index <tree-ish>::
git-diff-files [<pattern>...]::
compares the index and the files on the filesystem.
+The "git-diff-tree" command begins its output by printing the hash of
+what is being compared. After that, all the commands print one output
+line per changed file.
An output line is formatted this way:
. path for "dst"; only exists for C or R.
. an LF or a NUL when '-z' option is used, to terminate the record.
+Possible status letters are:
+
+- A: addition of a file
+- C: copy of a file into a new one
+- D: deletion of a file
+- M: modification of the contents or mode of a file
+- R: renaming of a file
+- T: change in the type of the file
+- U: file is unmerged (you must complete the merge before it can
+be committed)
+- X: "unknown" change type (most probably a bug, please report it)
+
+Status letters C and R are always followed by a score (denoting the
+percentage of similarity between the source and target of the move or
+copy), and are the only ones to be so.
+
<sha1> is shown as all 0's if a file is new on the filesystem
and it is out of sync with the index.
in pathnames are represented as `\t`, `\n`, and `\\`,
respectively.
+diff format for merges
+----------------------
+
+"git-diff-tree", "git-diff-files" and "git-diff --raw"
+can take '-c' or '--cc' option
+to generate diff output also for merge commits. The output differs
+from the format described above in the following way:
+
+. there is a colon for each parent
+. there are more "src" modes and "src" sha1
+. status is concatenated status characters for each parent
+. no optional "score" number
+. single path, only for "dst"
+
+Example:
+
+------------------------------------------------
+::100644 100644 100644 fabadb8... cc95eb0... 4866510... MM describe.c
+------------------------------------------------
+
+Note that 'combined diff' lists only files which were modified from
+all parents.
+
+
+include::diff-generate-patch.txt[]
+
+
+other diff formats
+------------------
+
+The `--summary` option describes newly added, deleted, renamed and
+copied files. The `--stat` option adds diffstat(1) graph to the
+output. These options can be combined with other options, such as
+`-p`, and are meant for human consumption.
+
+When showing a change that involves a rename or a copy, `--stat` output
+formats the pathnames compactly by combining common prefix and suffix of
+the pathnames. For example, a change that moves `arch/i386/Makefile` to
+`arch/x86/Makefile` while modifying 4 lines will be shown like this:
+
+------------------------------------
+arch/{i386 => x86}/Makefile | 4 +--
+------------------------------------
+
+The `--numstat` option gives the diffstat(1) information but is designed
+for easier machine consumption. An entry in `--numstat` output looks
+like this:
+
+----------------------------------------
+1 2 README
+3 1 arch/{i386 => x86}/Makefile
+----------------------------------------
+
+That is, from left to right:
+
+. the number of added lines;
+. a tab;
+. the number of deleted lines;
+. a tab;
+. pathname (possibly with rename/copy information);
+. a newline.
+
+When `-z` output option is in effect, the output is formatted this way:
+
+----------------------------------------
+1 2 README NUL
+3 1 NUL arch/i386/Makefile NUL arch/x86/Makefile NUL
+----------------------------------------
+
+That is:
+
+. the number of added lines;
+. a tab;
+. the number of deleted lines;
+. a tab;
+. a NUL (only exists if renamed/copied);
+. pathname in preimage;
+. a NUL (only exists if renamed/copied);
+. pathname in postimage (only exists if renamed/copied);
+. a NUL.
-Generating patches with -p
---------------------------
-
-When "git-diff-index", "git-diff-tree", or "git-diff-files" are run
-with a '-p' option, they do not produce the output described above;
-instead they produce a patch file.
-
-The patch generation can be customized at two levels.
-
-1. When the environment variable 'GIT_EXTERNAL_DIFF' is not set,
- these commands internally invoke "diff" like this:
-
- diff -L a/<path> -L b/<path> -pu <old> <new>
-+
-For added files, `/dev/null` is used for <old>. For removed
-files, `/dev/null` is used for <new>
-+
-The "diff" formatting options can be customized via the
-environment variable 'GIT_DIFF_OPTS'. For example, if you
-prefer context diff:
-
- GIT_DIFF_OPTS=-c git-diff-index -p HEAD
-
-
-2. When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
- program named by it is called, instead of the diff invocation
- described above.
-+
-For a path that is added, removed, or modified,
-'GIT_EXTERNAL_DIFF' is called with 7 parameters:
-
- path old-file old-hex old-mode new-file new-hex new-mode
-+
-where:
-
- <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
- contents of <old|new>,
- <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
- <old|new>-mode:: are the octal representation of the file modes.
-
-+
-The file parameters can point at the user's working file
-(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
-when a new file is added), or a temporary file (e.g. `old-file` in the
-index). 'GIT_EXTERNAL_DIFF' should not worry about unlinking the
-temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
-
-For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
-parameter, <path>.
-
-
-git specific extension to diff format
--------------------------------------
-
-What -p option produces is slightly different from the
-traditional diff format.
-
-1. It is preceded with a "git diff" header, that looks like
- this:
-
- diff --git a/file1 b/file2
-+
-The `a/` and `b/` filenames are the same unless rename/copy is
-involved. Especially, even for a creation or a deletion,
-`/dev/null` is _not_ used in place of `a/` or `b/` filenames.
-+
-When rename/copy is involved, `file1` and `file2` show the
-name of the source file of the rename/copy and the name of
-the file that rename/copy produces, respectively.
-
-2. It is followed by one or more extended header lines:
-
- old mode <mode>
- new mode <mode>
- deleted file mode <mode>
- new file mode <mode>
- copy from <path>
- copy to <path>
- rename from <path>
- rename to <path>
- similarity index <number>
- dissimilarity index <number>
- index <hash>..<hash> <mode>
-
-3. TAB, LF, and backslash characters in pathnames are
- represented as `\t`, `\n`, and `\\`, respectively.
+The extra `NUL` before the preimage path in renamed case is to allow
+scripts that read the output to tell if the current record being read is
+a single-path record or a rename/copy record without reading ahead.
+After reading added and deleted lines, reading up to `NUL` would yield
+the pathname, but if that is `NUL`, the record will show two paths.