1git-diff-cache(1) 2================= 3v0.1, May 2005 4 5NAME 6---- 7git-diff-cache - Compares content and mode of blobs between the cache and repository 8 9 10SYNOPSIS 11-------- 12'git-diff-cache' [-p] [-r] [-z] [-m] [--cached] [-R] [-B] [-M] [-C] [--find-copies-harder] [-O<orderfile>] [-S<string>] [--pickaxe-all] <tree-ish> [<path>...] 13 14DESCRIPTION 15----------- 16Compares the content and mode of the blobs found via a tree 17object with the content of the current cache and, optionally 18ignoring the stat state of the file on disk. When paths are 19specified, compares only those named paths. Otherwise all 20entries in the cache are compared. 21 22OPTIONS 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--find-copies-harder:: 48 By default, -C option finds copies only if the original 49 file of the copy was modified in the same changeset for 50 performance reasons. This flag makes the command 51 inspect unmodified files as candidates for the source of 52 copy. This is a very expensive operation for large 53 projects, so use it with caution. 54 55-S<string>:: 56 Look for differences that contains the change in <string>. 57 58--pickaxe-all:: 59 When -S finds a change, show all the changes in that 60 changeset, not just the files that contains the change 61 in <string>. 62 63-O<orderfile>:: 64 Output the patch in the order specified in the 65 <orderfile>, which has one shell glob pattern per line. 66 67-R:: 68 Swap two inputs; that is, show differences from cache or 69 on-disk file to tree contents. 70 71--cached:: 72 do not consider the on-disk file at all 73 74-m:: 75 By default, files recorded in the index but not checked 76 out are reported as deleted. This flag makes 77 "git-diff-cache" say that all non-checked-out files are up 78 to date. 79 80Output format 81------------- 82include::diff-format.txt[] 83 84Operating Modes 85--------------- 86You can choose whether you want to trust the index file entirely 87(using the '--cached' flag) or ask the diff logic to show any files 88that don't match the stat state as being "tentatively changed". Both 89of these operations are very useful indeed. 90 91Cached Mode 92----------- 93If '--cached' is specified, it allows you to ask: 94 95 show me the differences between HEAD and the current index 96 contents (the ones I'd write with a "git-write-tree") 97 98For example, let's say that you have worked on your index file, and are 99ready to commit. You want to see eactly *what* you are going to commit is 100without having to write a new tree object and compare it that way, and to 101do that, you just do 102 103 git-diff-cache --cached $(cat .git/HEAD) 104 105Example: let's say I had renamed `commit.c` to `git-commit.c`, and I had 106done an "git-update-cache" to make that effective in the index file. 107"git-diff-files" wouldn't show anything at all, since the index file 108matches my working directory. But doing a "git-diff-cache" does: 109 110 torvalds@ppc970:~/git> git-diff-cache --cached $(cat .git/HEAD) 111 -100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c 112 +100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c 113 114You can trivially see that the above is a rename. 115 116In fact, "git-diff-cache --cached" *should* always be entirely equivalent to 117actually doing a "git-write-tree" and comparing that. Except this one is much 118nicer for the case where you just want to check where you are. 119 120So doing a "git-diff-cache --cached" is basically very useful when you are 121asking yourself "what have I already marked for being committed, and 122what's the difference to a previous tree". 123 124Non-cached Mode 125--------------- 126The "non-cached" mode takes a different approach, and is potentially 127the more useful of the two in that what it does can't be emulated with 128a "git-write-tree" + "git-diff-tree". Thus that's the default mode. 129The non-cached version asks the question: 130 131 show me the differences between HEAD and the currently checked out 132 tree - index contents _and_ files that aren't up-to-date 133 134which is obviously a very useful question too, since that tells you what 135you *could* commit. Again, the output matches the "git-diff-tree -r" 136output to a tee, but with a twist. 137 138The twist is that if some file doesn't match the cache, we don't have 139a backing store thing for it, and we use the magic "all-zero" sha1 to 140show that. So let's say that you have edited `kernel/sched.c`, but 141have not actually done a "git-update-cache" on it yet - there is no 142"object" associated with the new state, and you get: 143 144 torvalds@ppc970:~/v2.6/linux> git-diff-cache $(cat .git/HEAD ) 145 *100644->100664 blob 7476bb......->000000...... kernel/sched.c 146 147ie it shows that the tree has changed, and that `kernel/sched.c` has is 148not up-to-date and may contain new stuff. The all-zero sha1 means that to 149get the real diff, you need to look at the object in the working directory 150directly rather than do an object-to-object diff. 151 152NOTE! As with other commands of this type, "git-diff-cache" does not 153actually look at the contents of the file at all. So maybe 154`kernel/sched.c` hasn't actually changed, and it's just that you 155touched it. In either case, it's a note that you need to 156"git-upate-cache" it to make the cache be in sync. 157 158NOTE 2! You can have a mixture of files show up as "has been updated" 159and "is still dirty in the working directory" together. You can always 160tell which file is in which state, since the "has been updated" ones 161show a valid sha1, and the "not in sync with the index" ones will 162always have the special all-zero sha1. 163 164 165Author 166------ 167Written by Linus Torvalds <torvalds@osdl.org> 168 169Documentation 170-------------- 171Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>. 172 173GIT 174--- 175Part of the link:git.html[git] suite 176