git-merge(1)



GIT-MERGE(1)                      Git Manual                      GIT-MERGE(1)

NAME
       git-merge - Join two or more development histories together

SYNOPSIS
       git merge [-n] [--stat] [--no-commit] [--squash] [--[no-]edit]
               [-s <strategy>] [-X <strategy-option>] [-S[<keyid>]]
               [--[no-]allow-unrelated-histories]
               [--[no-]rerere-autoupdate] [-m <msg>] [<commit>...]
       git merge --abort
       git merge --continue

DESCRIPTION
       Incorporates changes from the named commits (since the time their
       histories diverged from the current branch) into the current branch.
       This command is used by git pull to incorporate changes from another
       repository and can be used by hand to merge changes from one branch
       into another.

       Assume the following history exists and the current branch is "master":

                     A---B---C topic
                    /
               D---E---F---G master

       Then "git merge topic" will replay the changes made on the topic branch
       since it diverged from master (i.e., E) until its current commit (C) on
       top of master, and record the result in a new commit along with the
       names of the two parent commits and a log message from the user
       describing the changes.

                     A---B---C topic
                    /         \
               D---E---F---G---H master

       The second syntax ("git merge --abort") can only be run after the merge
       has resulted in conflicts. git merge --abort will abort the merge
       process and try to reconstruct the pre-merge state. However, if there
       were uncommitted changes when the merge started (and especially if
       those changes were further modified after the merge was started), git
       merge --abort will in some cases be unable to reconstruct the original
       (pre-merge) changes. Therefore:

       Warning: Running git merge with non-trivial uncommitted changes is
       discouraged: while possible, it may leave you in a state that is hard
       to back out of in the case of a conflict.

       The fourth syntax ("git merge --continue") can only be run after the
       merge has resulted in conflicts.

OPTIONS
       --commit, --no-commit
           Perform the merge and commit the result. This option can be used to
           override --no-commit.

           With --no-commit perform the merge but pretend the merge failed and
           do not autocommit, to give the user a chance to inspect and further
           tweak the merge result before committing.

       --edit, -e, --no-edit
           Invoke an editor before committing successful mechanical merge to
           further edit the auto-generated merge message, so that the user can
           explain and justify the merge. The --no-edit option can be used to
           accept the auto-generated message (this is generally discouraged).
           The --edit (or -e) option is still useful if you are giving a draft
           message with the -m option from the command line and want to edit
           it in the editor.

           Older scripts may depend on the historical behaviour of not
           allowing the user to edit the merge log message. They will see an
           editor opened when they run git merge. To make it easier to adjust
           such scripts to the updated behaviour, the environment variable
           GIT_MERGE_AUTOEDIT can be set to no at the beginning of them.

       --ff
           When the merge resolves as a fast-forward, only update the branch
           pointer, without creating a merge commit. This is the default
           behavior.

       --no-ff
           Create a merge commit even when the merge resolves as a
           fast-forward. This is the default behaviour when merging an
           annotated (and possibly signed) tag.

       --ff-only
           Refuse to merge and exit with a non-zero status unless the current
           HEAD is already up to date or the merge can be resolved as a
           fast-forward.

       -S[<keyid>], --gpg-sign[=<keyid>]
           GPG-sign the resulting merge commit. The keyid argument is optional
           and defaults to the committer identity; if specified, it must be
           stuck to the option without a space.

       --log[=<n>], --no-log
           In addition to branch names, populate the log message with one-line
           descriptions from at most <n> actual commits that are being merged.
           See also git-fmt-merge-msg(1).

           With --no-log do not list one-line descriptions from the actual
           commits being merged.

       --stat, -n, --no-stat
           Show a diffstat at the end of the merge. The diffstat is also
           controlled by the configuration option merge.stat.

           With -n or --no-stat do not show a diffstat at the end of the
           merge.

       --squash, --no-squash
           Produce the working tree and index state as if a real merge
           happened (except for the merge information), but do not actually
           make a commit, move the HEAD, or record $GIT_DIR/MERGE_HEAD (to
           cause the next git commit command to create a merge commit). This
           allows you to create a single commit on top of the current branch
           whose effect is the same as merging another branch (or more in case
           of an octopus).

           With --no-squash perform the merge and commit the result. This
           option can be used to override --squash.

       -s <strategy>, --strategy=<strategy>
           Use the given merge strategy; can be supplied more than once to
           specify them in the order they should be tried. If there is no -s
           option, a built-in list of strategies is used instead (git
           merge-recursive when merging a single head, git merge-octopus
           otherwise).

       -X <option>, --strategy-option=<option>
           Pass merge strategy specific option through to the merge strategy.

       --verify-signatures, --no-verify-signatures
           Verify that the tip commit of the side branch being merged is
           signed with a valid key, i.e. a key that has a valid uid: in the
           default trust model, this means the signing key has been signed by
           a trusted key. If the tip commit of the side branch is not signed
           with a valid key, the merge is aborted.

       --summary, --no-summary
           Synonyms to --stat and --no-stat; these are deprecated and will be
           removed in the future.

       -q, --quiet
           Operate quietly. Implies --no-progress.

       -v, --verbose
           Be verbose.

       --progress, --no-progress
           Turn progress on/off explicitly. If neither is specified, progress
           is shown if standard error is connected to a terminal. Note that
           not all merge strategies may support progress reporting.

       --allow-unrelated-histories
           By default, git merge command refuses to merge histories that do
           not share a common ancestor. This option can be used to override
           this safety when merging histories of two projects that started
           their lives independently. As that is a very rare occasion, no
           configuration variable to enable this by default exists and will
           not be added.

       --signoff
           Add Signed-off-by line by the committer at the end of the commit
           log message. The meaning of a signoff depends on the project, but
           it typically certifies that committer has the rights to submit this
           work under the same license and agrees to a Developer Certificate
           of Origin (see http://developercertificate.org/ for more
           information).

       -m <msg>
           Set the commit message to be used for the merge commit (in case one
           is created).

           If --log is specified, a shortlog of the commits being merged will
           be appended to the specified message.

           The git fmt-merge-msg command can be used to give a good default
           for automated git merge invocations. The automated message can
           include the branch description.

       --[no-]rerere-autoupdate
           Allow the rerere mechanism to update the index with the result of
           auto-conflict resolution if possible.

       --abort
           Abort the current conflict resolution process, and try to
           reconstruct the pre-merge state.

           If there were uncommitted worktree changes present when the merge
           started, git merge --abort will in some cases be unable to
           reconstruct these changes. It is therefore recommended to always
           commit or stash your changes before running git merge.

           git merge --abort is equivalent to git reset --merge when
           MERGE_HEAD is present.

       --continue
           After a git merge stops due to conflicts you can conclude the merge
           by running git merge --continue (see "HOW TO RESOLVE CONFLICTS"
           section below).

       <commit>...
           Commits, usually other branch heads, to merge into our branch.
           Specifying more than one commit will create a merge with more than
           two parents (affectionately called an Octopus merge).

           If no commit is given from the command line, merge the
           remote-tracking branches that the current branch is configured to
           use as its upstream. See also the configuration section of this
           manual page.

           When FETCH_HEAD (and no other commit) is specified, the branches
           recorded in the .git/FETCH_HEAD file by the previous invocation of
           git fetch for merging are merged to the current branch.

PRE-MERGE CHECKS
       Before applying outside changes, you should get your own work in good
       shape and committed locally, so it will not be clobbered if there are
       conflicts. See also git-stash(1). git pull and git merge will stop
       without doing anything when local uncommitted changes overlap with
       files that git pull/git merge may need to update.

       To avoid recording unrelated changes in the merge commit, git pull and
       git merge will also abort if there are any changes registered in the
       index relative to the HEAD commit. (One exception is when the changed
       index entries are in the state that would result from the merge
       already.)

       If all named commits are already ancestors of HEAD, git merge will exit
       early with the message "Already up to date."

FAST-FORWARD MERGE
       Often the current branch head is an ancestor of the named commit. This
       is the most common case especially when invoked from git pull: you are
       tracking an upstream repository, you have committed no local changes,
       and now you want to update to a newer upstream revision. In this case,
       a new commit is not needed to store the combined history; instead, the
       HEAD (along with the index) is updated to point at the named commit,
       without creating an extra merge commit.

       This behavior can be suppressed with the --no-ff option.

TRUE MERGE
       Except in a fast-forward merge (see above), the branches to be merged
       must be tied together by a merge commit that has both of them as its
       parents.

       A merged version reconciling the changes from all branches to be merged
       is committed, and your HEAD, index, and working tree are updated to it.
       It is possible to have modifications in the working tree as long as
       they do not overlap; the update will preserve them.

       When it is not obvious how to reconcile the changes, the following
       happens:

        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.

MERGING TAG
       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

HOW CONFLICTS ARE PRESENTED
       During a merge, the working tree files are updated to reflect the
       result of the merge. Among the changes made to the common ancestor's
       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;
           let's 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 Barbie's remark on your side. The only thing you can tell
       is that your side wants to say it is hard and you'd 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;
           let's 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.

HOW TO RESOLVE CONFLICTS
       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 or git merge --continue to seal the deal. The latter
           command checks whether there is a (interrupted) merge in progress
           before calling git commit.

       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.

EXAMPLES
       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.

MERGE STRATEGIES
       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.

       resolve
           This 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.

       recursive
           This 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:

           ours
               This 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.

           theirs
               This is the opposite of ours; note that, unlike ours, there is
               no theirs merge stragegy to confuse this merge option with.

           patience
               With 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-eol
               Treats 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.

           renormalize
               This 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-renormalize
               Disables the renormalize option. This overrides the
               merge.renormalize configuration variable.

           no-renames
               Turn off rename detection. See also git-diff(1) --no-renames.

           find-renames[=<n>]
               Turn on rename detection, optionally setting the similarity
               threshold. This is the default. See also git-diff(1)
               --find-renames.

           rename-threshold=<n>
               Deprecated synonym for find-renames=<n>.

           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.

       octopus
           This 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.

       ours
           This 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.

       subtree
           This 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.

CONFIGURATION
       merge.conflictStyle
           Specify 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.defaultToUpstream
           If 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.ff
           By 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.branchdesc
           In addition to branch names, populate the log message with the
           branch description text associated with them. Defaults to false.

       merge.log
           In 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.renameLimit
           The number of files to consider when performing rename detection
           during a merge; if not specified, defaults to the value of
           diff.renameLimit.

       merge.renormalize
           Tell 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.stat
           Whether to print the diffstat between ORIG_HEAD and the merge
           result at the end of the merge. True by default.

       merge.tool
           Controls 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.

           o   araxis

           o   bc

           o   bc3

           o   codecompare

           o   deltawalker

           o   diffmerge

           o   diffuse

           o   ecmerge

           o   emerge

           o   examdiff

           o   gvimdiff

           o   gvimdiff2

           o   gvimdiff3

           o   kdiff3

           o   meld

           o   opendiff

           o   p4merge

           o   tkdiff

           o   tortoisemerge

           o   vimdiff

           o   vimdiff2

           o   vimdiff3

           o   winmerge

           o   xxdiff

       merge.verbosity
           Controls 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>.name
           Defines a human-readable name for a custom low-level merge driver.
           See gitattributes(5) for details.

       merge.<driver>.driver
           Defines the command that implements a custom low-level merge
           driver. See gitattributes(5) for details.

       merge.<driver>.recursive
           Names a low-level merge driver to be used when performing an
           internal merge between common ancestors. See gitattributes(5) for
           details.

       branch.<name>.mergeOptions
           Sets 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.

SEE ALSO
       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)

GIT
       Part of the git(1) suite

Git 2.15.0                        10/30/2017                      GIT-MERGE(1)

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