You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
113 lines
3.4 KiB
113 lines
3.4 KiB
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] [--octopus] <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. |
|
|
|
Unless `--octopus` is given, 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 the most common |
|
special case, specifying only two commits on the command line means |
|
computing the merge base between the given two commits. |
|
|
|
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. |
|
|
|
OPTIONS |
|
------- |
|
-a:: |
|
--all:: |
|
Output all merge bases for the commits, instead of just one. |
|
|
|
--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'. |
|
|
|
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. |
|
|
|
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
|
|
|