git/Documentation/git-diff.txt
Denton Liu 3d09c22869 builtin/diff-tree: learn --merge-base
The previous commit introduced ---merge-base a way to take the diff
between the working tree or index and the merge base between an arbitrary
commit and HEAD. It makes sense to extend this option to support the
case where two commits are given too and behave in a manner identical to
`git diff A...B`.

Introduce the --merge-base flag as an alternative to triple-dot
notation. Thus, we would be able to write the above as
`git diff --merge-base A B`.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-21 13:37:03 -07:00

225 lines
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git-diff(1)
===========
NAME
----
git-diff - Show changes between commits, commit and working tree, etc
SYNOPSIS
--------
[verse]
'git diff' [<options>] [<commit>] [--] [<path>...]
'git diff' [<options>] --cached [--merge-base] [<commit>] [--] [<path>...]
'git diff' [<options>] [--merge-base] <commit> [<commit>...] <commit> [--] [<path>...]
'git diff' [<options>] <commit>...<commit> [--] [<path>...]
'git diff' [<options>] <blob> <blob>
'git diff' [<options>] --no-index [--] <path> <path>
DESCRIPTION
-----------
Show changes between the working tree and the index or a tree, changes
between the index and a tree, changes between two trees, changes resulting
from a merge, changes between two blob objects, or changes between two
files on disk.
'git diff' [<options>] [--] [<path>...]::
This form is to view the changes you made relative to
the index (staging area for the next commit). In other
words, the differences are what you _could_ tell Git to
further add to the index but you still haven't. You can
stage these changes by using linkgit:git-add[1].
'git diff' [<options>] --no-index [--] <path> <path>::
This form is to compare the given two paths on the
filesystem. You can omit the `--no-index` option when
running the command in a working tree controlled by Git and
at least one of the paths points outside the working tree,
or when running the command outside a working tree
controlled by Git. This form implies `--exit-code`.
'git diff' [<options>] --cached [--merge-base] [<commit>] [--] [<path>...]::
This form is to view the changes you staged for the next
commit relative to the named <commit>. Typically you
would want comparison with the latest commit, so if you
do not give <commit>, it defaults to HEAD.
If HEAD does not exist (e.g. unborn branches) and
<commit> is not given, it shows all staged changes.
--staged is a synonym of --cached.
+
If --merge-base is given, instead of using <commit>, use the merge base
of <commit> and HEAD. `git diff --merge-base A` is equivalent to
`git diff $(git merge-base A HEAD)`.
'git diff' [<options>] <commit> [--] [<path>...]::
This form is to view the changes you have in your
working tree relative to the named <commit>. You can
use HEAD to compare it with the latest commit, or a
branch name to compare with the tip of a different
branch.
'git diff' [<options>] [--merge-base] <commit> <commit> [--] [<path>...]::
This is to view the changes between two arbitrary
<commit>.
+
If --merge-base is given, use the merge base of the two commits for the
"before" side. `git diff --merge-base A B` is equivalent to
`git diff $(git merge-base A B) B`.
'git diff' [<options>] <commit> <commit>... <commit> [--] [<path>...]::
This form is to view the results of a merge commit. The first
listed <commit> must be the merge itself; the remaining two or
more commits should be its parents. A convenient way to produce
the desired set of revisions is to use the `^@` suffix.
For instance, if `master` names a merge commit, `git diff master
master^@` gives the same combined diff as `git show master`.
'git diff' [<options>] <commit>..<commit> [--] [<path>...]::
This is synonymous to the earlier form (without the `..`) for
viewing the changes between two arbitrary <commit>. If <commit> on
one side is omitted, it will have the same effect as
using HEAD instead.
'git diff' [<options>] <commit>\...<commit> [--] [<path>...]::
This form is to view the changes on the branch containing
and up to the second <commit>, starting at a common ancestor
of both <commit>. `git diff A...B` is equivalent to
`git diff $(git merge-base A B) B`. You can omit any one
of <commit>, which has the same effect as using HEAD instead.
Just in case you are doing something exotic, it should be
noted that all of the <commit> in the above description, except
in the `--merge-base` case and in the last two forms that use `..`
notations, can be any <tree>.
For a more complete list of ways to spell <commit>, see
"SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
However, "diff" is about comparing two _endpoints_, not ranges,
and the range notations (`<commit>..<commit>` and
`<commit>...<commit>`) do not mean a range as defined in the
"SPECIFYING RANGES" section in linkgit:gitrevisions[7].
'git diff' [<options>] <blob> <blob>::
This form is to view the differences between the raw
contents of two blob objects.
OPTIONS
-------
:git-diff: 1
include::diff-options.txt[]
-1 --base::
-2 --ours::
-3 --theirs::
Compare the working tree with the "base" version (stage #1),
"our branch" (stage #2) or "their branch" (stage #3). The
index contains these stages only for unmerged entries i.e.
while resolving conflicts. See linkgit:git-read-tree[1]
section "3-Way Merge" for detailed information.
-0::
Omit diff output for unmerged entries and just show
"Unmerged". Can be used only when comparing the working tree
with the index.
<path>...::
The <paths> parameters, when given, are used to limit
the diff to the named paths (you can give directory
names and get diff for all files under them).
include::diff-format.txt[]
EXAMPLES
--------
Various ways to check your working tree::
+
------------
$ git diff <1>
$ git diff --cached <2>
$ git diff HEAD <3>
------------
+
<1> Changes in the working tree not yet staged for the next commit.
<2> Changes between the index and your last commit; what you
would be committing if you run `git commit` without `-a` option.
<3> Changes in the working tree since your last commit; what you
would be committing if you run `git commit -a`
Comparing with arbitrary commits::
+
------------
$ git diff test <1>
$ git diff HEAD -- ./test <2>
$ git diff HEAD^ HEAD <3>
------------
+
<1> Instead of using the tip of the current branch, compare with the
tip of "test" branch.
<2> Instead of comparing with the tip of "test" branch, compare with
the tip of the current branch, but limit the comparison to the
file "test".
<3> Compare the version before the last commit and the last commit.
Comparing branches::
+
------------
$ git diff topic master <1>
$ git diff topic..master <2>
$ git diff topic...master <3>
------------
+
<1> Changes between the tips of the topic and the master branches.
<2> Same as above.
<3> Changes that occurred on the master branch since when the topic
branch was started off it.
Limiting the diff output::
+
------------
$ git diff --diff-filter=MRC <1>
$ git diff --name-status <2>
$ git diff arch/i386 include/asm-i386 <3>
------------
+
<1> Show only modification, rename, and copy, but not addition
or deletion.
<2> Show only names and the nature of change, but not actual
diff output.
<3> Limit diff output to named subtrees.
Munging the diff output::
+
------------
$ git diff --find-copies-harder -B -C <1>
$ git diff -R <2>
------------
+
<1> Spend extra cycles to find renames, copies and complete
rewrites (very expensive).
<2> Output diff in reverse.
SEE ALSO
--------
diff(1),
linkgit:git-difftool[1],
linkgit:git-log[1],
linkgit:gitdiffcore[7],
linkgit:git-format-patch[1],
linkgit:git-apply[1],
linkgit:git-show[1]
GIT
---
Part of the linkgit:git[1] suite