path: root/Documentation/git-diff-index.txt
diff options
authorJunio C Hamano <>2005-09-08 00:26:23 (GMT)
committerJunio C Hamano <>2005-09-08 00:45:20 (GMT)
commit215a7ad1ef790467a4cd3f0dcffbd6e5f04c38f7 (patch)
tree6bc7aa4f652d0ef49108d9e30a7ea7fbf8e44639 /Documentation/git-diff-index.txt
parent99977bd5fdeabbd0608a70e9411c243007ec4ea2 (diff)
Big tool rename.
As promised, this is the "big tool rename" patch. The primary differences since 0.99.6 are: (1) git-*-script are no more. The commands installed do not have any such suffix so users do not have to remember if something is implemented as a shell script or not. (2) Many command names with 'cache' in them are renamed with 'index' if that is what they mean. There are backward compatibility symblic links so that you and Porcelains can keep using the old names, but the backward compatibility support is expected to be removed in the near future. Signed-off-by: Junio C Hamano <>
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+v0.1, May 2005
+git-diff-index - Compares content and mode of blobs between the cache and repository
+'git-diff-index' [-m] [--cached] [<common diff options>] <tree-ish> [<path>...]
+Compares the content and mode of the blobs found via a tree
+object with the content of the current cache and, optionally
+ignoring the stat state of the file on disk. When paths are
+specified, compares only those named paths. Otherwise all
+entries in the cache are compared.
+ The id of a tree object to diff against.
+ do not consider the on-disk file at all
+ By default, files recorded in the index but not checked
+ out are reported as deleted. This flag makes
+ "git-diff-index" say that all non-checked-out files are up
+ to date.
+Output format
+Operating Modes
+You can choose whether you want to trust the index file entirely
+(using the '--cached' flag) or ask the diff logic to show any files
+that don't match the stat state as being "tentatively changed". Both
+of these operations are very useful indeed.
+Cached Mode
+If '--cached' is specified, it allows you to ask:
+ show me the differences between HEAD and the current cache
+ 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 cache and are ready to commit. You want to see eactly
+*what* you are going to commit is without having to write a new tree
+object and compare it that way, and to do that, you just do
+ git-diff-index --cached $(cat .git/HEAD)
+Example: 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 $(cat .git/HEAD)
+ -100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c
+ +100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c
+You can trivially see 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".
+Non-cached Mode
+The "non-cached" mode takes a different approach, and is potentially
+the more useful of the two in that what it does can't be emulated with
+a "git-write-tree" + "git-diff-tree". Thus that's the default mode.
+The non-cached version asks the question:
+ show me the differences between HEAD and the currently checked out
+ tree - index contents _and_ files that aren't up-to-date
+which 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 cache, 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 $(cat .git/HEAD )
+ *100644->100664 blob 7476bb......->000000...... kernel/sched.c
+ie 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-upate-cache" it to make the cache be in sync.
+NOTE 2! 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.
+Written by Linus Torvalds <>
+Documentation by David Greaves, Junio C Hamano and the git-list <>.
+Part of the link:git.html[git] suite