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] [-B] [-M] [-R] [-C] [-O<orderfile>] [-S<string>] [--pickaxe-all] [--cached] <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-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 Swap two inputs; that is, show differences from cache or 61 on-disk file to tree contents. 62 63--cached:: 64 do not consider the on-disk file at all 65 66-m:: 67 By default, files recorded in the index but not checked 68 out are reported as deleted. This flag makes 69 "git-diff-cache" say that all non-checked-out files are up 70 to date. 71 72Output format 73------------- 74include::diff-format.txt[] 75 76Operating Modes 77--------------- 78You can choose whether you want to trust the index file entirely 79(using the '--cached' flag) or ask the diff logic to show any files 80that don't match the stat state as being "tentatively changed". Both 81of these operations are very useful indeed. 82 83Cached Mode 84----------- 85If '--cached' is specified, it allows you to ask: 86 87 show me the differences between HEAD and the current index 88 contents (the ones I'd write with a "git-write-tree") 89 90For example, let's say that you have worked on your index file, and are 91ready to commit. You want to see eactly *what* you are going to commit is 92without having to write a new tree object and compare it that way, and to 93do that, you just do 94 95 git-diff-cache --cached $(cat .git/HEAD) 96 97Example: let's say I had renamed `commit.c` to `git-commit.c`, and I had 98done an "git-update-cache" to make that effective in the index file. 99"git-diff-files" wouldn't show anything at all, since the index file 100matches my working directory. But doing a "git-diff-cache" does: 101 102 torvalds@ppc970:~/git> git-diff-cache --cached $(cat .git/HEAD) 103 -100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c 104 +100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c 105 106You can trivially see that the above is a rename. 107 108In fact, "git-diff-cache --cached" *should* always be entirely equivalent to 109actually doing a "git-write-tree" and comparing that. Except this one is much 110nicer for the case where you just want to check where you are. 111 112So doing a "git-diff-cache --cached" is basically very useful when you are 113asking yourself "what have I already marked for being committed, and 114what's the difference to a previous tree". 115 116Non-cached Mode 117--------------- 118The "non-cached" mode takes a different approach, and is potentially 119the more useful of the two in that what it does can't be emulated with 120a "git-write-tree" + "git-diff-tree". Thus that's the default mode. 121The non-cached version asks the question: 122 123 show me the differences between HEAD and the currently checked out 124 tree - index contents _and_ files that aren't up-to-date 125 126which is obviously a very useful question too, since that tells you what 127you *could* commit. Again, the output matches the "git-diff-tree -r" 128output to a tee, but with a twist. 129 130The twist is that if some file doesn't match the cache, we don't have 131a backing store thing for it, and we use the magic "all-zero" sha1 to 132show that. So let's say that you have edited `kernel/sched.c`, but 133have not actually done a "git-update-cache" on it yet - there is no 134"object" associated with the new state, and you get: 135 136 torvalds@ppc970:~/v2.6/linux> git-diff-cache $(cat .git/HEAD ) 137 *100644->100664 blob 7476bb......->000000...... kernel/sched.c 138 139ie it shows that the tree has changed, and that `kernel/sched.c` has is 140not up-to-date and may contain new stuff. The all-zero sha1 means that to 141get the real diff, you need to look at the object in the working directory 142directly rather than do an object-to-object diff. 143 144NOTE! As with other commands of this type, "git-diff-cache" does not 145actually look at the contents of the file at all. So maybe 146`kernel/sched.c` hasn't actually changed, and it's just that you 147touched it. In either case, it's a note that you need to 148"git-upate-cache" it to make the cache be in sync. 149 150NOTE 2! You can have a mixture of files show up as "has been updated" 151and "is still dirty in the working directory" together. You can always 152tell which file is in which state, since the "has been updated" ones 153show a valid sha1, and the "not in sync with the index" ones will 154always have the special all-zero sha1. 155 156 157Author 158------ 159Written by Linus Torvalds <torvalds@osdl.org> 160 161Documentation 162-------------- 163Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>. 164 165GIT 166--- 167Part of the link:git.html[git] suite 168