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git/Documentation/diff-format.txt
Junio C Hamano f604652e05 git-diff --numstat -z: make it machine readable
The "-z" format is all about machine parsability, but showing renamed
paths as "common/{a => b}/suffix" makes it impossible.  The scripts would
never have successfully parsed "--numstat -z -M" in the old format.

This fixes the output format in a (hopefully minimally) backward
incompatible way.

 * The output without -z is not changed.  This has given a good way for
   humans to view added and deleted lines separately, and showing the
   path in combined, shorter way would preserve readability.

 * The output with -z is unchanged for paths that do not involve renames.
   Existing scripts that do not pass -M/-C are not affected at all.

 * The output with -z for a renamed path is shown in a format that can
   easily be distinguished from an unrenamed path.

This is based on Jakub Narebski's patch.  Bugs and documentation typos
are mine.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-12-12 10:59:22 -08:00

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The 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>::
compares the <tree-ish> and the files on the filesystem.
git-diff-index --cached <tree-ish>::
compares the <tree-ish> and the index.
git-diff-tree [-r] <tree-ish-1> <tree-ish-2> [<pattern>...]::
compares the trees named by the two arguments.
git-diff-files [<pattern>...]::
compares the index and the files on the filesystem.
An output line is formatted this way:
------------------------------------------------
in-place edit :100644 100644 bcd1234... 0123456... M file0
copy-edit :100644 100644 abcd123... 1234567... C68 file1 file2
rename-edit :100644 100644 abcd123... 1234567... R86 file1 file3
create :000000 100644 0000000... 1234567... A file4
delete :100644 000000 1234567... 0000000... D file5
unmerged :000000 000000 0000000... 0000000... U file6
------------------------------------------------
That is, from the left to the right:
. a colon.
. mode for "src"; 000000 if creation or unmerged.
. a space.
. mode for "dst"; 000000 if deletion or unmerged.
. a space.
. sha1 for "src"; 0\{40\} if creation or unmerged.
. a space.
. sha1 for "dst"; 0\{40\} if creation, unmerged or "look at work tree".
. a space.
. status, followed by optional "score" number.
. a tab or a NUL when '-z' option is used.
. path for "src"
. a tab or a NUL when '-z' option is used; only exists for C or R.
. path for "dst"; only exists for C or R.
. an LF or a NUL when '-z' option is used, to terminate the record.
<sha1> is shown as all 0's if a file is new on the filesystem
and it is out of sync with the index.
Example:
------------------------------------------------
:100644 100644 5be4a4...... 000000...... M file.c
------------------------------------------------
When `-z` option is not used, TAB, LF, and backslash characters
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.
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.