122 lines
4.5 KiB
Text
122 lines
4.5 KiB
Text
git-diff-index(1)
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=================
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NAME
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----
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git-diff-index - Compare a tree to the working tree or index
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SYNOPSIS
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--------
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[verse]
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'git diff-index' [-m] [--cached] [<common diff options>] <tree-ish> [<path>...]
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DESCRIPTION
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-----------
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Compares the content and mode of the blobs found in a tree object
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with the corresponding tracked files in the working tree, or with the
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corresponding paths in the index. When <path> arguments are present,
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compares only paths matching those patterns. Otherwise all tracked
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files are compared.
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OPTIONS
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-------
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include::diff-options.txt[]
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<tree-ish>::
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The id of a tree object to diff against.
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--cached::
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do not consider the on-disk file at all
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-m::
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By default, files recorded in the index but not checked
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out are reported as deleted. This flag makes
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'git diff-index' say that all non-checked-out files are up
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to date.
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include::diff-format.txt[]
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OPERATING MODES
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---------------
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You can choose whether you want to trust the index file entirely
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(using the `--cached` flag) or ask the diff logic to show any files
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that don't match the stat state as being "tentatively changed". Both
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of these operations are very useful indeed.
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CACHED MODE
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-----------
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If `--cached` is specified, it allows you to ask:
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show me the differences between HEAD and the current index
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contents (the ones I'd write using 'git write-tree')
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For example, let's say that you have worked on your working directory, updated
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some files in the index and are ready to commit. You want to see exactly
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*what* you are going to commit, without having to write a new tree
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object and compare it that way, and to do that, you just do
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git diff-index --cached HEAD
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Example: let's say I had renamed `commit.c` to `git-commit.c`, and I had
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done an `update-index` to make that effective in the index file.
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`git diff-files` wouldn't show anything at all, since the index file
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matches my working directory. But doing a 'git diff-index' does:
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torvalds@ppc970:~/git> git diff-index --cached HEAD
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-100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 commit.c
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+100644 blob 4161aecc6700a2eb579e842af0b7f22b98443f74 git-commit.c
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You can see easily that the above is a rename.
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In fact, `git diff-index --cached` *should* always be entirely equivalent to
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actually doing a 'git write-tree' and comparing that. Except this one is much
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nicer for the case where you just want to check where you are.
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So doing a `git diff-index --cached` is basically very useful when you are
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asking yourself "what have I already marked for being committed, and
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what's the difference to a previous tree".
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NON-CACHED MODE
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---------------
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The "non-cached" mode takes a different approach, and is potentially
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the more useful of the two in that what it does can't be emulated with
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a 'git write-tree' + 'git diff-tree'. Thus that's the default mode.
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The non-cached version asks the question:
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show me the differences between HEAD and the currently checked out
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tree - index contents _and_ files that aren't up to date
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which is obviously a very useful question too, since that tells you what
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you *could* commit. Again, the output matches the 'git diff-tree -r'
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output to a tee, but with a twist.
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The twist is that if some file doesn't match the index, we don't have
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a backing store thing for it, and we use the magic "all-zero" sha1 to
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show that. So let's say that you have edited `kernel/sched.c`, but
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have not actually done a 'git update-index' on it yet - there is no
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"object" associated with the new state, and you get:
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torvalds@ppc970:~/v2.6/linux> git diff-index --abbrev HEAD
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:100644 100664 7476bb... 000000... kernel/sched.c
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i.e., it shows that the tree has changed, and that `kernel/sched.c` is
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not up to date and may contain new stuff. The all-zero sha1 means that to
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get the real diff, you need to look at the object in the working directory
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directly rather than do an object-to-object diff.
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NOTE: As with other commands of this type, 'git diff-index' does not
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actually look at the contents of the file at all. So maybe
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`kernel/sched.c` hasn't actually changed, and it's just that you
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touched it. In either case, it's a note that you need to
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'git update-index' it to make the index be in sync.
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NOTE: You can have a mixture of files show up as "has been updated"
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and "is still dirty in the working directory" together. You can always
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tell which file is in which state, since the "has been updated" ones
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show a valid sha1, and the "not in sync with the index" ones will
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always have the special all-zero sha1.
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GIT
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---
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Part of the linkgit:git[1] suite
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