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+git-merge-base(1)
+=================
+
+NAME
+----
+git-merge-base - Find as good common ancestors as possible for a merge
+
+
+SYNOPSIS
+--------
+[verse]
+'git merge-base' [-a|--all] <commit> <commit>...
+'git merge-base' [-a|--all] --octopus <commit>...
+'git merge-base' --independent <commit>...
+
+DESCRIPTION
+-----------
+
+'git merge-base' finds best common ancestor(s) between two commits to use
+in a three-way merge.  One common ancestor is 'better' than another common
+ancestor if the latter is an ancestor of the former.  A common ancestor
+that does not have any better common ancestor is a 'best common
+ancestor', i.e. a 'merge base'.  Note that there can be more than one
+merge base for a pair of commits.
+
+OPERATION MODE
+--------------
+
+As the most common special case, specifying only two commits on the
+command line means computing the merge base between the given two commits.
+
+More generally, among the two commits to compute the merge base from,
+one is specified by the first commit argument on the command line;
+the other commit is a (possibly hypothetical) commit that is a merge
+across all the remaining commits on the command line.
+
+As a consequence, the 'merge base' is not necessarily contained in each of the
+commit arguments if more than two commits are specified. This is different
+from linkgit:git-show-branch[1] when used with the `--merge-base` option.
+
+--octopus::
+	Compute the best common ancestors of all supplied commits,
+	in preparation for an n-way merge.  This mimics the behavior
+	of 'git show-branch --merge-base'.
+
+--independent::
+	Instead of printing merge bases, print a minimal subset of
+	the supplied commits with the same ancestors.  In other words,
+	among the commits given, list those which cannot be reached
+	from any other.  This mimics the behavior of 'git show-branch
+	--independent'.
+
+OPTIONS
+-------
+-a::
+--all::
+	Output all merge bases for the commits, instead of just one.
+
+DISCUSSION
+----------
+
+Given two commits 'A' and 'B', `git merge-base A B` will output a commit
+which is reachable from both 'A' and 'B' through the parent relationship.
+
+For example, with this topology:
+
+		 o---o---o---B
+		/
+	---o---1---o---o---o---A
+
+the merge base between 'A' and 'B' is '1'.
+
+Given three commits 'A', 'B' and 'C', `git merge-base A B C` will compute the
+merge base between 'A' and a hypothetical commit 'M', which is a merge
+between 'B' and 'C'.  For example, with this topology:
+
+	       o---o---o---o---C
+	      /
+	     /   o---o---o---B
+	    /   /
+	---2---1---o---o---o---A
+
+the result of `git merge-base A B C` is '1'.  This is because the
+equivalent topology with a merge commit 'M' between 'B' and 'C' is:
+
+
+	       o---o---o---o---o
+	      /                 \
+	     /   o---o---o---o---M
+	    /   /
+	---2---1---o---o---o---A
+
+and the result of `git merge-base A M` is '1'.  Commit '2' is also a
+common ancestor between 'A' and 'M', but '1' is a better common ancestor,
+because '2' is an ancestor of '1'.  Hence, '2' is not a merge base.
+
+The result of `git merge-base --octopus A B C` is '2', because '2' is
+the best common ancestor of all commits.
+
+When the history involves criss-cross merges, there can be more than one
+'best' common ancestor for two commits.  For example, with this topology:
+
+       ---1---o---A
+	   \ /
+	    X
+	   / \
+       ---2---o---o---B
+
+both '1' and '2' are merge-bases of A and B.  Neither one is better than
+the other (both are 'best' merge bases).  When the `--all` option is not given,
+it is unspecified which best one is output.
+
+See also
+--------
+linkgit:git-rev-list[1],
+linkgit:git-show-branch[1],
+linkgit:git-merge[1]
+
+GIT
+---
+Part of the linkgit:git[1] suite