These commands all compare two sets of things; what is compared differs:
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 file6That is, from the left to the right:
Example:
:100644 100644 5be4a4...... 000000...... M file.cWhen -z option is not used, TAB, LF, and backslash characters in pathnames are represented as \t, \n, and \\, respectively.
The patch generation can be customized at two levels.
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
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-modewhere: <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>.
diff --git a/file1 b/file2The 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.
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>
diff --combined describe.c
index fabadb8,cc95eb0..4866510
--- a/describe.c
+++ b/describe.c
@@@ -98,20 -98,12 +98,20 @@@
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;
struct commit_list *list;
static int initialized = 0;
struct commit_name *n;
+ if (get_sha1(arg, sha1) < 0)
+ usage(describe_usage);
+ cmit = lookup_commit_reference(sha1);
+ if (!cmit)
+ usage(describe_usage);
+
if (!initialized) {
initialized = 1;
for_each_ref(get_name);
diff --combined fileor like this (when --cc option is used):
diff --c file
index <hash>,<hash>..<hash> mode <mode>,<mode>..<mode> new file mode <mode> deleted file mode <mode>,<mode>The mode <mode>,<mode>..<mode> line appears only if at least one of the <mode> is diferent from the rest. Extended headers with information about detected contents movement (renames and copying detection) are designed to work with diff of two <tree-ish> and are not used by combined diff format.
--- a/file +++ b/fileSimilar to two-line header for traditional unified diff format, /dev/null is used to signal created or deleted files.
@@@ <from-file-range> <from-file-range> <to-file-range> @@@There are (number of parents + 1) @ characters in the chunk header for combined diff format. 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 result. A + character in the column N means that the line appears in the last file, and fileN does not have that line (in other words, the line was added, from the point of view of that parent).
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").
show me the differences between HEAD and the current index contents (the ones I'd write with a "git-write-tree")For example, let's say that you have worked on your working directory, updated some files in the index and are ready to commit. You want to see exactly what you are going to commit, without having to write a new tree object and compare it that way, and to do that, you just do
git-diff-index --cached HEADExample: let's say I had renamed commit.c to git-commit.c, and I had done an "git-update-index" to make that effective in the index file. "git-diff-files" wouldn't show anything at all, since the index file matches my working directory. But doing a "git-diff-index" does:
torvalds@ppc970:~/git> git-diff-index --cached HEAD -100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c +100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.cYou can see easily that the above is a rename.
In fact, "git-diff-index --cached" should always be entirely equivalent to actually doing a "git-write-tree" and comparing that. Except this one is much nicer for the case where you just want to check where you are.
So doing a "git-diff-index --cached" is basically very useful when you are asking yourself "what have I already marked for being committed, and what's the difference to a previous tree".
show me the differences between HEAD and the currently checked out tree - index contents _and_ files that aren't up-to-datewhich is obviously a very useful question too, since that tells you what you could commit. Again, the output matches the "git-diff-tree -r" output to a tee, but with a twist.
The twist is that if some file doesn't match the index, we don't have a backing store thing for it, and we use the magic "all-zero" sha1 to show that. So let's say that you have edited kernel/sched.c, but have not actually done a "git-update-index" on it yet - there is no "object" associated with the new state, and you get:
torvalds@ppc970:~/v2.6/linux> git-diff-index HEAD *100644->100664 blob 7476bb......->000000...... kernel/sched.ci.e., it shows that the tree has changed, and that kernel/sched.c has is not up-to-date and may contain new stuff. The all-zero sha1 means that to get the real diff, you need to look at the object in the working directory directly rather than do an object-to-object diff.
Note As with other commands of this type, "git-diff-index" does not actually look at the contents of the file at all. So maybe kernel/sched.c hasn't actually changed, and it's just that you touched it. In either case, it's a note that you need to "git-update-index" it to make the index be in sync.
Note You can have a mixture of files show up as "has been updated" and "is still dirty in the working directory" together. You can always tell which file is in which state, since the "has been updated" ones show a valid sha1, and the "not in sync with the index" ones will always have the special all-zero sha1.