[PATCH] Add -O<orderfile> option to diff-* brothers.
[git/git.git] / Documentation / git-diff-cache.txt
1 git-diff-cache(1)
2 =================
3 v0.1, May 2005
4
5 NAME
6 ----
7 git-diff-cache - Compares content and mode of blobs between the cache and repository
8
9
10 SYNOPSIS
11 --------
12 'git-diff-cache' [-p] [-r] [-z] [-m] [-B] [-M] [-R] [-C] [-O<orderfile>] [-S<string>] [--pickaxe-all] [--cached] <tree-ish> [<path>...]
13
14 DESCRIPTION
15 -----------
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.
21
22 OPTIONS
23 -------
24 <tree-ish>::
25 The id of a tree object to diff against.
26
27 -p::
28 Generate patch (see section on generating patches)
29
30 -r::
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.
34
35 -z::
36 \0 line termination on output
37
38 -B::
39 Break complete rewrite changes into pairs of delete and create.
40
41 -M::
42 Detect renames.
43
44 -C::
45 Detect copies as well as renames.
46
47 -S<string>::
48 Look for differences that contains the change in <string>.
49
50 --pickaxe-all::
51 When -S finds a change, show all the changes in that
52 changeset, not just the files that contains the change
53 in <string>.
54
55 -O<orderfile>::
56 Output the patch in the order specified in the
57 <orderfile>, which has one shell glob pattern per line.
58
59 -R::
60 Output diff in reverse.
61
62 --cached::
63 do not consider the on-disk file at all
64
65 -m::
66 By default, files recorded in the index but not checked
67 out are reported as deleted. This flag makes
68 "git-diff-cache" say that all non-checked-out files are up
69 to date.
70
71 Output format
72 -------------
73 include::diff-format.txt[]
74
75 Operating Modes
76 ---------------
77 You can choose whether you want to trust the index file entirely
78 (using the '--cached' flag) or ask the diff logic to show any files
79 that don't match the stat state as being "tentatively changed". Both
80 of these operations are very useful indeed.
81
82 Cached Mode
83 -----------
84 If '--cached' is specified, it allows you to ask:
85
86 show me the differences between HEAD and the current index
87 contents (the ones I'd write with a "git-write-tree")
88
89 For example, let's say that you have worked on your index file, and are
90 ready to commit. You want to see eactly *what* you are going to commit is
91 without having to write a new tree object and compare it that way, and to
92 do that, you just do
93
94 git-diff-cache --cached $(cat .git/HEAD)
95
96 Example: let's say I had renamed `commit.c` to `git-commit.c`, and I had
97 done an "git-update-cache" to make that effective in the index file.
98 "git-diff-files" wouldn't show anything at all, since the index file
99 matches my working directory. But doing a "git-diff-cache" does:
100
101 torvalds@ppc970:~/git> git-diff-cache --cached $(cat .git/HEAD)
102 -100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c
103 +100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c
104
105 You can trivially see that the above is a rename.
106
107 In fact, "git-diff-cache --cached" *should* always be entirely equivalent to
108 actually doing a "git-write-tree" and comparing that. Except this one is much
109 nicer for the case where you just want to check where you are.
110
111 So doing a "git-diff-cache --cached" is basically very useful when you are
112 asking yourself "what have I already marked for being committed, and
113 what's the difference to a previous tree".
114
115 Non-cached Mode
116 ---------------
117 The "non-cached" mode takes a different approach, and is potentially
118 the more useful of the two in that what it does can't be emulated with
119 a "git-write-tree" + "git-diff-tree". Thus that's the default mode.
120 The non-cached version asks the question:
121
122 show me the differences between HEAD and the currently checked out
123 tree - index contents _and_ files that aren't up-to-date
124
125 which is obviously a very useful question too, since that tells you what
126 you *could* commit. Again, the output matches the "git-diff-tree -r"
127 output to a tee, but with a twist.
128
129 The twist is that if some file doesn't match the cache, we don't have
130 a backing store thing for it, and we use the magic "all-zero" sha1 to
131 show that. So let's say that you have edited `kernel/sched.c`, but
132 have not actually done a "git-update-cache" on it yet - there is no
133 "object" associated with the new state, and you get:
134
135 torvalds@ppc970:~/v2.6/linux> git-diff-cache $(cat .git/HEAD )
136 *100644->100664 blob 7476bb......->000000...... kernel/sched.c
137
138 ie it shows that the tree has changed, and that `kernel/sched.c` has is
139 not up-to-date and may contain new stuff. The all-zero sha1 means that to
140 get the real diff, you need to look at the object in the working directory
141 directly rather than do an object-to-object diff.
142
143 NOTE! As with other commands of this type, "git-diff-cache" does not
144 actually look at the contents of the file at all. So maybe
145 `kernel/sched.c` hasn't actually changed, and it's just that you
146 touched it. In either case, it's a note that you need to
147 "git-upate-cache" it to make the cache be in sync.
148
149 NOTE 2! You can have a mixture of files show up as "has been updated"
150 and "is still dirty in the working directory" together. You can always
151 tell which file is in which state, since the "has been updated" ones
152 show a valid sha1, and the "not in sync with the index" ones will
153 always have the special all-zero sha1.
154
155
156 Author
157 ------
158 Written by Linus Torvalds <torvalds@osdl.org>
159
160 Documentation
161 --------------
162 Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
163
164 GIT
165 ---
166 Part of the link:git.html[git] suite
167