The combination of what is compared with what is determined by
the number of ents given to the command.
-`----------------`--------`-----------------------------`------------------
-Number of ents Options What's Compared Underlying command
----------------------------------------------------------------------------
-0 - index file and working tree git-diff-files
-1 --cached ent and index file git-diff-index
-1 - ent and working tree git-diff-index
-2 - two ents git-diff-tree
----------------------------------------------------------------------------
+* When no <ent> is given, the working tree and the index
+ file is compared, using `git-diff-files`.
+
+* When one <ent> is given, the working tree and the named
+ tree is compared, using `git-diff-index`. The option
+ `--cached` can be given to compare the index file and
+ the named tree.
+
+* When two <ent>s are given, these two trees are compared
+ using `git-diff-tree`.
OPTIONS
-------
commands.
+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 since your last git-update-index.
+<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.
+------------
+
+
+Limiting the diff output::
++
+------------
+$ git diff --diff-filter=MRC <1>
+$ git diff --name-status -r <2>
+$ git diff arch/i386 include/asm-i386 <3>
+
+<1> show only modification, rename and copy, but not addition
+nor deletion.
+<2> show only names and the nature of change, but not actual
+diff output. --name-status disables usual patch generation
+which in turn also disables recursive behaviour, so without -r
+you would only see the directory name if there is a change in a
+file in a subdirectory.
+<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.
+------------
+
+
Author
------
Written by Linus Torvalds <torvalds@osdl.org>