-The output format from "git-diff-cache", "git-diff-tree" and
-"git-diff-files" is very similar.
+The output format from "git-diff-index", "git-diff-tree" and
+"git-diff-files" are very similar.
-These commands all compare two sets of things; what are
-compared are different:
+These commands all compare two sets of things; what is
+compared differs:
-git-diff-cache <tree-ish>::
+git-diff-index <tree-ish>::
compares the <tree-ish> and the files on the filesystem.
-git-diff-cache --cached <tree-ish>::
- compares the <tree-ish> and the cache.
+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 cache and the files on the filesystem.
+ compares the index and the files on the filesystem.
-The following desription uses "old" and "new" to mean those
-compared entities.
-For files in old but not in new (i.e. removed):
+An output line is formatted this way:
- -<mode> \t <type> \t <object> \t <path>
+------------------------------------------------
+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
+------------------------------------------------
-For files not in old but in new (i.e. added):
+That is, from the left to the right:
- +<mode> \t <type> \t <object> \t <path>
+. 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.
-For files that differ:
+<sha1> is shown as all 0's if a file is new on the filesystem
+and it is out of sync with the index.
- *<old-mode>-><new-mode> \t <type> \t <old-sha1>-><new-sha1> \t <path>
+Example:
-<new-sha1> is shown as all 0's if new is a file on the
-filesystem and it is out of sync with the cache. Example:
+------------------------------------------------
+:100644 100644 5be4a4...... 000000...... M file.c
+------------------------------------------------
- *100644->100644 blob 5be4a4.......->000000....... file.c
+When `-z` option is not used, TAB, LF, and backslash characters
+in pathnames are represented as `\t`, `\n`, and `\\`,
+respectively.
Generating patches with -p
--------------------------
-When "git-diff-cache", "git-diff-tree", or "git-diff-files" are run
-with a '-p' option, they do not produce the output described above
+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. This
-customization also applies to "git-diff-tree-helper".
+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
a/<path> -pu <old> <new>
+ 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>
environment variable 'GIT_DIFF_OPTS'. For example, if you
prefer context diff:
- GIT_DIFF_OPTS=-c git-diff-cache -p $(cat .git/HEAD)
+ GIT_DIFF_OPTS=-c git-diff-index -p HEAD
2. When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
where:
<old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
- contents of <old|ne>,
+ 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
-cache). 'GIT_EXTERNAL_DIFF' should not worry about unlinking 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.
+
+
+combined diff format
+--------------------
+
+git-diff-tree and git-diff-files can take '-c' or '--cc' option
+to produce 'combined diff', which looks like this:
+
+------------
+diff --combined describe.c
+@@@ +98,7 @@@
+ return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
+ }
+
+- static void describe(char *arg)
+ -static void describe(struct commit *cmit, int last_one)
+++static void describe(char *arg, int last_one)
+ {
+ + unsigned char sha1[20];
+ + struct commit *cmit;
+------------
+
+Unlike the traditional 'unified' diff format, which shows two
+files A and B with a single column that has `-` (minus --
+appears in A but removed in B), `+` (plus -- missing in A but
+added to B), or ` ` (space -- unchanged) prefix, this format
+compares two or more files file1, file2,... with one file X, and
+shows how X differs from each of fileN. One column for each of
+fileN is prepended to the output line to note how X's line is
+different from it.
+
+A `-` character in the column N means that the line appears in
+fileN but it does not appear in the last file. A `+` character
+in the column N means that the line appears in the last file,
+and fileN does not have that line.
+
+In the above example output, the function signature was changed
+from both files (hence two `-` removals from both file1 and
+file2, plus `++` to mean one line that was added does not appear
+in either file1 nor file2). Also two other lines are the same
+from file1 but do not appear in file2 (hence prefixed with ` +`).
+
+When shown by `git diff-tree -c`, it compares the parents of a
+merge commit with the merge result (i.e. file1..fileN are the
+parents). When shown by `git diff-files -c`, it compares the
+two unresolved merge parents with the working tree file
+(i.e. file1 is stage 2 aka "our version", file2 is stage 3 aka
+"their version").
+