GIT-MERGE-INDEX(1) Git Manual GIT-MERGE-INDEX(1)NAME
git-merge-index - Run a merge for files needing merging
SYNOPSIS
git merge-index [-o] [-q] <merge-program> (-a | [--] <file>*)
DESCRIPTION
This looks up the <file>(s) in the index and, if there are any merge entries, passes the SHA-1 hash for those files as arguments 1, 2, 3
(empty argument if no file), and <file> as argument 4. File modes for the three files are passed as arguments 5, 6 and 7.
OPTIONS --
Do not interpret any more arguments as options.
-a
Run merge against all files in the index that need merging.
-o
Instead of stopping at the first failed merge, do all of them in one shot - continue with merging even when previous merges returned
errors, and only return the error code after all the merges.
-q
Do not complain about a failed merge program (a merge program failure usually indicates conflicts during the merge). This is for
porcelains which might want to emit custom messages.
If git merge-index is called with multiple <file>s (or -a) then it processes them in turn only stopping if merge returns a non-zero exit
code.
Typically this is run with a script calling Git's imitation of the merge command from the RCS package.
A sample script called git merge-one-file is included in the distribution.
ALERT ALERT ALERT! The Git "merge object order" is different from the RCS merge program merge object order. In the above ordering, the
original is first. But the argument order to the 3-way merge program merge is to have the original in the middle. Don't ask me why.
Examples:
torvalds@ppc970:~/merge-test> git merge-index cat MM
This is MM from the original tree. # original
This is modified MM in the branch A. # merge1
This is modified MM in the branch B. # merge2
This is modified MM in the branch B. # current contents
or
torvalds@ppc970:~/merge-test> git merge-index cat AA MM
cat: : No such file or directory
This is added AA in the branch A.
This is added AA in the branch B.
This is added AA in the branch B.
fatal: merge program failed
where the latter example shows how git merge-index will stop trying to merge once anything has returned an error (i.e., cat returned an
error for the AA file, because it didn't exist in the original, and thus git merge-index didn't even try to merge the MM thing).
GIT
Part of the git(1) suite
Git 1.8.3.1 06/10/2014 GIT-MERGE-INDEX(1)
Check Out this Related Man Page
GIT-MERGE-BASE(1) Git Manual GIT-MERGE-BASE(1)NAME
git-merge-base - Find as good common ancestors as possible for a merge
SYNOPSIS
git merge-base [-a|--all] <commit> <commit>...
git merge-base [-a|--all] --octopus <commit>...
git merge-base --is-ancestor <commit> <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 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.
--is-ancestor
Check if the first <commit> is an ancestor of the second <commit>, and exit with status 0 if true, or with status 1 if not. Errors are
signaled by a non-zero status that is not 1.
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.
A common idiom to check "fast-forward-ness" between two commits A and B is (or at least used to be) to compute the merge base between A and
B, and check if it is the same as A, in which case, A is an ancestor of B. You will see this idiom used often in older scripts.
A=$(git rev-parse --verify A)
if test "$A" = "$(git merge-base A B)"
then
... A is an ancestor of B ...
fi
In modern git, you can say this in a more direct way:
if git merge-base --is-ancestor A B
then
... A is an ancestor of B ...
fi
instead.
SEE ALSO git-rev-list(1), git-show-branch(1), git-merge(1)GIT
Part of the git(1) suite
Git 1.8.5.3 01/14/2014 GIT-MERGE-BASE(1)