57fe64a40d
This cleans up the way calls are made into the diff core from diff-tree family and diff-helper. Earlier, these programs had "if (generating_patch)" sprinkled all over the place, but those ugliness are gone and handled uniformly from the diff core, even when not generating patch format. This also allowed diff-cache and diff-files to acquire -R (reverse) option to generate diff in reverse. Users of diff-tree can swap two trees easily so I did not add -R there. [ Linus' note: I'll add -R to "diff-tree" too, since a "commit diff" doesn't have another tree to switch around: the other tree is always the parent(s) of the commit ] Also -M<digits-as-mantissa> suggestion made by Linus has been implemented. Documentation updates are also included. Signed-off-by: Junio C Hamano <junkio@cox.net> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
148 lines
4.9 KiB
Plaintext
148 lines
4.9 KiB
Plaintext
git-diff-cache(1)
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=================
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v0.1, May 2005
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NAME
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----
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git-diff-cache - Compares content and mode of blobs between the cache and repository
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SYNOPSIS
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--------
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'git-diff-cache' [-p] [-r] [-z] [-m] [-M] [-R] [--cached] <tree-ish>
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DESCRIPTION
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-----------
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Compares the content and mode of the blobs found via a tree object
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with the content of the current cache and, optionally ignoring the
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stat state of the file on disk.
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OPTIONS
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-------
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<tree-ish>::
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The id of a tree object to diff against.
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-p::
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Generate patch (see section on generating patches)
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-r::
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This flag does not mean anything. It is there only to match
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"git-diff-tree". Unlike "git-diff-tree", "git-diff-cache"
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always looks at all the subdirectories.
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-z::
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\0 line termination on output
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-M::
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Detect renames; implies -p.
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-R::
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Output diff in reverse.
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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-cache" say that all non-checked-out files are up
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to date.
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Output format
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-------------
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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 with a "git-write-tree")
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For example, let's say that you have worked on your index file, and are
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ready to commit. You want to see eactly *what* you are going to commit is
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without having to write a new tree object and compare it that way, and to
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do that, you just do
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git-diff-cache --cached $(cat .git/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 "git-update-cache" 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-cache" does:
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torvalds@ppc970:~/git> git-diff-cache --cached $(cat .git/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 trivially see that the above is a rename.
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In fact, "git-diff-cache --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-cache --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 cache, 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-cache" 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-cache $(cat .git/HEAD )
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*100644->100664 blob 7476bb......->000000...... kernel/sched.c
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ie it shows that the tree has changed, and that `kernel/sched.c` has 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-cache" 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-upate-cache" it to make the cache be in sync.
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NOTE 2! 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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Author
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------
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Written by Linus Torvalds <torvalds@osdl.org>
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Documentation
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--------------
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Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
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GIT
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---
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Part of the link:git.html[git] suite
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