|1.||The HEAD pointer stays the same.|
2. The MERGE_HEAD ref is set to point to the other branch head.
3. Paths that merged cleanly are updated both in the index file and in your working tree.
4. For conflicting paths, the index file records up to three versions: stage 1 stores the version from the common ancestor, stage 2 from HEAD, and stage 3 from MERGE_HEAD (you can inspect the stages with git ls-files -u). The working tree files contain the result of the "merge" program; i.e. 3-way merge results with familiar conflict markers <<<===>>>.
5. No other changes are made. In particular, the local modifications you had before you started merge will stay the same and the index entries for them stay as they were, i.e. matching HEAD.
If you tried a merge which resulted in complex conflicts and want to start over, you can recover with git merge --abort.
When merging an annotated (and possibly signed) tag, Git always creates a merge commit even if a fast-forward merge is possible, and the commit message template is prepared with the tag message. Additionally, if the tag is signed, the signature check is reported as a comment in the message template. See also git-tag(1).
When you want to just integrate with the work leading to the commit that happens to be tagged, e.g. synchronizing with an upstream release point, you may not want to make an unnecessary merge commit.
In such a case, you can "unwrap" the tag yourself before feeding it to git merge, or pass --ff-only when you do not have any work on your own. e.g.
git fetch origin git merge v1.2.3^0 git merge --ff-only v1.2.3
During a merge, the working tree files are updated to reflect the result of the merge. Among the changes made to the common ancestors version, non-overlapping ones (that is, you changed an area of the file while the other side left that area intact, or vice versa) are incorporated in the final result verbatim. When both sides made changes to the same area, however, Git cannot randomly pick one side over the other, and asks you to resolve it by leaving what both sides did to that area.
By default, Git uses the same style as the one used by the "merge" program from the RCS suite to present such a conflicted hunk, like this:
Here are lines that are either unchanged from the common ancestor, or cleanly resolved because only one side changed. <<<<<<< yours:sample.txt Conflict resolution is hard; lets go shopping. ======= Git makes conflict resolution easy. >>>>>>> theirs:sample.txt And here is another line that is cleanly resolved or unmodified.
The area where a pair of conflicting changes happened is marked with markers <<<<<<<, =======, and >>>>>>>. The part before the ======= is typically your side, and the part afterwards is typically their side.
The default format does not show what the original said in the conflicting area. You cannot tell how many lines are deleted and replaced with Barbies remark on your side. The only thing you can tell is that your side wants to say it is hard and youd prefer to go shopping, while the other side wants to claim it is easy.
An alternative style can be used by setting the "merge.conflictStyle" configuration variable to "diff3". In "diff3" style, the above conflict may look like this:
Here are lines that are either unchanged from the common ancestor, or cleanly resolved because only one side changed. <<<<<<< yours:sample.txt Conflict resolution is hard; lets go shopping. ||||||| Conflict resolution is hard. ======= Git makes conflict resolution easy. >>>>>>> theirs:sample.txt And here is another line that is cleanly resolved or unmodified.
In addition to the <<<<<<<, =======, and >>>>>>> markers, it uses another ||||||| marker that is followed by the original text. You can tell that the original just stated a fact, and your side simply gave in to that statement and gave up, while the other side tried to have a more positive attitude. You can sometimes come up with a better resolution by viewing the original.
After seeing a conflict, you can do two things:
o Decide not to merge. The only clean-ups you need are to reset the index file to the HEAD commit to reverse 2. and to clean up working tree changes made by 2. and 3.; git merge --abort can be used for this.
o Resolve the conflicts. Git will mark the conflicts in the working tree. Edit the files into shape and git add them to the index. Use git commit to seal the deal.
You can work through the conflict with a number of tools:
o Use a mergetool. git mergetool to launch a graphical mergetool which will work you through the merge.
o Look at the diffs. git diff will show a three-way diff, highlighting changes from both the HEAD and MERGE_HEAD versions.
o Look at the diffs from each branch. git log --merge -p <path> will show diffs first for the HEAD version and then the MERGE_HEAD version.
o Look at the originals. git show :1:filename shows the common ancestor, git show :2:filename shows the HEAD version, and git show :3:filename shows the MERGE_HEAD version.
o Merge branches fixes and enhancements on top of the current branch, making an octopus merge:
$ git merge fixes enhancements
o Merge branch obsolete into the current branch, using ours merge strategy:
$ git merge -s ours obsolete
o Merge branch maint into the current branch, but do not make a new commit automatically:
$ git merge --no-commit maint
This can be used when you want to include further changes to the merge, or want to write your own merge commit message.
You should refrain from abusing this option to sneak substantial changes into a merge commit. Small fixups like bumping release/version name would be acceptable.
The merge mechanism (git merge and git pull commands) allows the backend merge strategies to be chosen with -s option. Some strategies can also take their own options, which can be passed by giving -X<option> arguments to git merge and/or git pull.
resolveThis can only resolve two heads (i.e. the current branch and another branch you pulled from) using a 3-way merge algorithm. It tries to carefully detect criss-cross merge ambiguities and is considered generally safe and fast.
recursiveThis can only resolve two heads using a 3-way merge algorithm. When there is more than one common ancestor that can be used for 3-way merge, it creates a merged tree of the common ancestors and uses that as the reference tree for the 3-way merge. This has been reported to result in fewer merge conflicts without causing mismerges by tests done on actual merge commits taken from Linux 2.6 kernel development history. Additionally this can detect and handle merges involving renames. This is the default merge strategy when pulling or merging one branch.
The recursive strategy can take the following options:
oursThis option forces conflicting hunks to be auto-resolved cleanly by favoring our version. Changes from the other tree that do not conflict with our side are reflected to the merge result. For a binary file, the entire contents are taken from our side.
This should not be confused with the ours merge strategy, which does not even look at what the other tree contains at all. It discards everything the other tree did, declaring our history contains all that happened in it.
theirsThis is the opposite of ours.
patienceWith this option, merge-recursive spends a little extra time to avoid mismerges that sometimes occur due to unimportant matching lines (e.g., braces from distinct functions). Use this when the branches to be merged have diverged wildly. See also git-diff(1)--patience.
diff-algorithm=[patience|minimal|histogram|myers]Tells merge-recursive to use a different diff algorithm, which can help avoid mismerges that occur due to unimportant matching lines (such as braces from distinct functions). See also git-diff(1)--diff-algorithm.
ignore-space-change, ignore-all-space, ignore-space-at-eolTreats lines with the indicated type of whitespace change as unchanged for the sake of a three-way merge. Whitespace changes mixed with other changes to a line are not ignored. See also git-diff(1)-b, -w, and --ignore-space-at-eol.
o If their version only introduces whitespace changes to a line, our version is used;
o If our version introduces whitespace changes but their version includes a substantial change, their version is used;
o Otherwise, the merge proceeds in the usual way.
renormalizeThis runs a virtual check-out and check-in of all three stages of a file when resolving a three-way merge. This option is meant to be used when merging branches with different clean filters or end-of-line normalization rules. See "Merging branches with differing checkin/checkout attributes" in gitattributes(5) for details.
no-renormalizeDisables the renormalize option. This overrides the merge.renormalize configuration variable.
rename-threshold=<n>Controls the similarity threshold used for rename detection. See also git-diff(1)-M.
subtree[=<path>]This option is a more advanced form of subtree strategy, where the strategy makes a guess on how two trees must be shifted to match with each other when merging. Instead, the specified path is prefixed (or stripped from the beginning) to make the shape of two trees to match.
octopusThis resolves cases with more than two heads, but refuses to do a complex merge that needs manual resolution. It is primarily meant to be used for bundling topic branch heads together. This is the default merge strategy when pulling or merging more than one branch.
oursThis resolves any number of heads, but the resulting tree of the merge is always that of the current branch head, effectively ignoring all changes from all other branches. It is meant to be used to supersede old development history of side branches. Note that this is different from the -Xours option to the recursive merge strategy.
subtreeThis is a modified recursive strategy. When merging trees A and B, if B corresponds to a subtree of A, B is first adjusted to match the tree structure of A, instead of reading the trees at the same level. This adjustment is also done to the common ancestor tree.
With the strategies that use 3-way merge (including the default, recursive), if a change is made on both branches, but later reverted on one of the branches, that change will be present in the merged result; some people find this behavior confusing. It occurs because only the heads and the merge base are considered when performing a merge, not the individual commits. The merge algorithm therefore considers the reverted change as no change at all, and substitutes the changed version instead.
merge.conflictStyleSpecify the style in which conflicted hunks are written out to working tree files upon merge. The default is "merge", which shows a <<<<<<< conflict marker, changes made by one side, a ======= marker, changes made by the other side, and then a >>>>>>> marker. An alternate style, "diff3", adds a ||||||| marker and the original text before the ======= marker.
merge.defaultToUpstreamIf merge is called without any commit argument, merge the upstream branches configured for the current branch by using their last observed values stored in their remote-tracking branches. The values of the branch.<current branch>.merge that name the branches at the remote named by branch.<current branch>.remote are consulted, and then they are mapped via remote.<remote>.fetch to their corresponding remote-tracking branches, and the tips of these tracking branches are merged.
merge.ffBy default, Git does not create an extra merge commit when merging a commit that is a descendant of the current commit. Instead, the tip of the current branch is fast-forwarded. When set to false, this variable tells Git to create an extra merge commit in such a case (equivalent to giving the --no-ff option from the command line). When set to only, only such fast-forward merges are allowed (equivalent to giving the --ff-only option from the command line).
merge.branchdescIn addition to branch names, populate the log message with the branch description text associated with them. Defaults to false.
merge.logIn addition to branch names, populate the log message with at most the specified number of one-line descriptions from the actual commits that are being merged. Defaults to false, and true is a synonym for 20.
merge.renameLimitThe number of files to consider when performing rename detection during a merge; if not specified, defaults to the value of diff.renameLimit.
merge.renormalizeTell Git that canonical representation of files in the repository has changed over time (e.g. earlier commits record text files with CRLF line endings, but recent ones use LF line endings). In such a repository, Git can convert the data recorded in commits to a canonical form before performing a merge to reduce unnecessary conflicts. For more information, see section "Merging branches with differing checkin/checkout attributes" in gitattributes(5).
merge.statWhether to print the diffstat between ORIG_HEAD and the merge result at the end of the merge. True by default.
merge.toolControls which merge tool is used by git-mergetool(1). The list below shows the valid built-in values. Any other value is treated as a custom merge tool and requires that a corresponding mergetool.<tool>.cmd variable is defined.
merge.verbosityControls the amount of output shown by the recursive merge strategy. Level 0 outputs nothing except a final error message if conflicts were detected. Level 1 outputs only conflicts, 2 outputs conflicts and file changes. Level 5 and above outputs debugging information. The default is level 2. Can be overridden by the GIT_MERGE_VERBOSITY environment variable.
merge.<driver>.nameDefines a human-readable name for a custom low-level merge driver. See gitattributes(5) for details.
merge.<driver>.driverDefines the command that implements a custom low-level merge driver. See gitattributes(5) for details.
merge.<driver>.recursiveNames a low-level merge driver to be used when performing an internal merge between common ancestors. See gitattributes(5) for details.
branch.<name>.mergeOptionsSets default options for merging into branch <name>. The syntax and supported options are the same as those of git merge, but option values containing whitespace characters are currently not supported.
git-fmt-merge-msg(1), git-pull(1), gitattributes(5), git-reset(1), git-diff(1), git-ls-files(1), git-add(1), git-rm(1), git-mergetool(1)
Part of the git(1) suite
|Git 2&.7&.4||GIT-MERGE (1)||03/17/2016|