7 git-diff-cache - Compares content and mode of blobs between the cache and repository
12 'git-diff-cache' [-p] [-r] [-z] [-m] [-B] [-M] [-R] [-C] [-S<string>] [--pickaxe-all] [--cached] <tree-ish> [<path>...]
16 Compares the content and mode of the blobs found via a tree
17 object with the content of the current cache and, optionally
18 ignoring the stat state of the file on disk. When paths are
19 specified, compares only those named paths. Otherwise all
20 entries in the cache are compared.
25 The id of a tree object to diff against.
28 Generate patch (see section on generating patches)
31 This flag does not mean anything. It is there only to match
32 "git-diff-tree". Unlike "git-diff-tree", "git-diff-cache"
33 always looks at all the subdirectories.
36 \0 line termination on output
39 Break complete rewrite changes into pairs of delete and create.
45 Detect copies as well as renames.
48 Look for differences that contains the change in <string>.
51 When -S finds a change, show all the changes in that
52 changeset, not just the files that contains the change
56 Output diff in reverse.
59 do not consider the on-disk file at all
62 By default, files recorded in the index but not checked
63 out are reported as deleted. This flag makes
64 "git-diff-cache" say that all non-checked-out files are up
69 include::diff-format.txt[]
73 You can choose whether you want to trust the index file entirely
74 (using the '--cached' flag) or ask the diff logic to show any files
75 that don't match the stat state as being "tentatively changed". Both
76 of these operations are very useful indeed.
80 If '--cached' is specified, it allows you to ask:
82 show me the differences between HEAD and the current index
83 contents (the ones I'd write with a "git-write-tree")
85 For example, let's say that you have worked on your index file, and are
86 ready to commit. You want to see eactly *what* you are going to commit is
87 without having to write a new tree object and compare it that way, and to
90 git-diff-cache --cached $(cat .git/HEAD)
92 Example: let's say I had renamed `commit.c` to `git-commit.c`, and I had
93 done an "git-update-cache" to make that effective in the index file.
94 "git-diff-files" wouldn't show anything at all, since the index file
95 matches my working directory. But doing a "git-diff-cache" does:
97 torvalds@ppc970:~/git> git-diff-cache --cached $(cat .git/HEAD)
98 -100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c
99 +100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c
101 You can trivially see that the above is a rename.
103 In fact, "git-diff-cache --cached" *should* always be entirely equivalent to
104 actually doing a "git-write-tree" and comparing that. Except this one is much
105 nicer for the case where you just want to check where you are.
107 So doing a "git-diff-cache --cached" is basically very useful when you are
108 asking yourself "what have I already marked for being committed, and
109 what's the difference to a previous tree".
113 The "non-cached" mode takes a different approach, and is potentially
114 the more useful of the two in that what it does can't be emulated with
115 a "git-write-tree" + "git-diff-tree". Thus that's the default mode.
116 The non-cached version asks the question:
118 show me the differences between HEAD and the currently checked out
119 tree - index contents _and_ files that aren't up-to-date
121 which is obviously a very useful question too, since that tells you what
122 you *could* commit. Again, the output matches the "git-diff-tree -r"
123 output to a tee, but with a twist.
125 The twist is that if some file doesn't match the cache, we don't have
126 a backing store thing for it, and we use the magic "all-zero" sha1 to
127 show that. So let's say that you have edited `kernel/sched.c`, but
128 have not actually done a "git-update-cache" on it yet - there is no
129 "object" associated with the new state, and you get:
131 torvalds@ppc970:~/v2.6/linux> git-diff-cache $(cat .git/HEAD )
132 *100644->100664 blob 7476bb......->000000...... kernel/sched.c
134 ie it shows that the tree has changed, and that `kernel/sched.c` has is
135 not up-to-date and may contain new stuff. The all-zero sha1 means that to
136 get the real diff, you need to look at the object in the working directory
137 directly rather than do an object-to-object diff.
139 NOTE! As with other commands of this type, "git-diff-cache" does not
140 actually look at the contents of the file at all. So maybe
141 `kernel/sched.c` hasn't actually changed, and it's just that you
142 touched it. In either case, it's a note that you need to
143 "git-upate-cache" it to make the cache be in sync.
145 NOTE 2! You can have a mixture of files show up as "has been updated"
146 and "is still dirty in the working directory" together. You can always
147 tell which file is in which state, since the "has been updated" ones
148 show a valid sha1, and the "not in sync with the index" ones will
149 always have the special all-zero sha1.
154 Written by Linus Torvalds <torvalds@osdl.org>
158 Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
162 Part of the link:git.html[git] suite