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<title>git-merge(1)</title>
</head>
<body>
<div id="header">
<h1>
git-merge(1) Manual Page
</h1>
<h2>NAME</h2>
<div class="sectionbody">
<p>git-merge -
Join two or more development histories together
</p>
</div>
</div>
<h2>SYNOPSIS</h2>
<div class="sectionbody">
<div class="verseblock">
<div class="content"><em>git merge</em> [-n] [--stat] [--no-commit] [--squash] [-s &lt;strategy&gt;]&#8230;
[-m &lt;msg&gt;] &lt;remote&gt; &lt;remote&gt;&#8230;
<em>git merge</em> &lt;msg&gt; HEAD &lt;remote&gt;&#8230;</div></div>
</div>
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="para"><p>This is the top-level interface to the merge machinery
which drives multiple merge strategy scripts.</p></div>
<div class="para"><p>The second syntax (&lt;msg&gt; <tt>HEAD</tt> &lt;remote&gt;) is supported for
historical reasons. Do not use it from the command line or in
new scripts. It is the same as <tt>git merge -m &lt;msg&gt; &lt;remote&gt;</tt>.</p></div>
</div>
<h2 id="_options">OPTIONS</h2>
<div class="sectionbody">
<div class="vlist"><dl>
<dt>
-q
</dt>
<dt>
--quiet
</dt>
<dd>
<p>
Operate quietly.
</p>
</dd>
<dt>
-v
</dt>
<dt>
--verbose
</dt>
<dd>
<p>
Be verbose.
</p>
</dd>
<dt>
--stat
</dt>
<dd>
<p>
Show a diffstat at the end of the merge. The diffstat is also
controlled by the configuration option merge.stat.
</p>
</dd>
<dt>
-n
</dt>
<dt>
--no-stat
</dt>
<dd>
<p>
Do not show a diffstat at the end of the merge.
</p>
</dd>
<dt>
--summary
</dt>
<dt>
--no-summary
</dt>
<dd>
<p>
Synonyms to --stat and --no-stat; these are deprecated and will be
removed in the future.
</p>
</dd>
<dt>
--log
</dt>
<dd>
<p>
In addition to branch names, populate the log message with
one-line descriptions from the actual commits that are being
merged.
</p>
</dd>
<dt>
--no-log
</dt>
<dd>
<p>
Do not list one-line descriptions from the actual commits being
merged.
</p>
</dd>
<dt>
--no-commit
</dt>
<dd>
<p>
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.
</p>
</dd>
<dt>
--commit
</dt>
<dd>
<p>
Perform the merge and commit the result. This option can
be used to override --no-commit.
</p>
</dd>
<dt>
--squash
</dt>
<dd>
<p>
Produce the working tree and index state as if a real
merge happened, but do not actually make a commit or
move the <tt>HEAD</tt>, nor record <tt>$GIT_DIR/MERGE_HEAD</tt> to
cause the next <tt>git commit</tt> 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).
</p>
</dd>
<dt>
--no-squash
</dt>
<dd>
<p>
Perform the merge and commit the result. This option can
be used to override --squash.
</p>
</dd>
<dt>
--no-ff
</dt>
<dd>
<p>
Generate a merge commit even if the merge resolved as a
fast-forward.
</p>
</dd>
<dt>
--ff
</dt>
<dd>
<p>
Do not generate a merge commit if the merge resolved as
a fast-forward, only update the branch pointer. This is
the default behavior of git-merge.
</p>
</dd>
<dt>
-s &lt;strategy&gt;
</dt>
<dt>
--strategy=&lt;strategy&gt;
</dt>
<dd>
<p>
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 <tt>-s</tt> option, a built-in list of strategies
is used instead (<em>git-merge-recursive</em> when merging a single
head, <em>git-merge-octopus</em> otherwise).
</p>
</dd>
<dt>
-m &lt;msg&gt;
</dt>
<dd>
<p>
The commit message to be used for the merge commit (in case
it is created). The <em>git-fmt-merge-msg</em> script can be used
to give a good default for automated <em>git-merge</em> invocations.
</p>
</dd>
<dt>
&lt;remote&gt;&#8230;
</dt>
<dd>
<p>
Other branch heads to merge into our branch. You need at
least one &lt;remote&gt;. Specifying more than one &lt;remote&gt;
obviously means you are trying an Octopus.
</p>
</dd>
</dl></div>
</div>
<h2 id="_merge_strategies">MERGE STRATEGIES</h2>
<div class="sectionbody">
<div class="vlist"><dl>
<dt>
resolve
</dt>
<dd>
<p>
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.
</p>
</dd>
<dt>
recursive
</dt>
<dd>
<p>
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 mis-merges 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.
</p>
</dd>
<dt>
octopus
</dt>
<dd>
<p>
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.
</p>
</dd>
<dt>
ours
</dt>
<dd>
<p>
This resolves any number of heads, but the result of the
merge is always the current branch head. It is meant to
be used to supersede old development history of side
branches.
</p>
</dd>
<dt>
subtree
</dt>
<dd>
<p>
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.
</p>
</dd>
</dl></div>
<div class="para"><p>If you tried a merge which resulted in complex conflicts and
want to start over, you can recover with <em>git-reset</em>.</p></div>
</div>
<h2 id="_configuration">CONFIGURATION</h2>
<div class="sectionbody">
<div class="vlist"><dl>
<dt>
merge.conflictstyle
</dt>
<dd>
<p>
Specify the style in which conflicted hunks are written out to
working tree files upon merge. The default is "merge", which
shows a <tt>&lt;&lt;&lt;&lt;&lt;&lt;&lt;</tt> conflict marker, changes made by one side,
a <tt>=======</tt> marker, changes made by the other side, and then
a <tt>&gt;&gt;&gt;&gt;&gt;&gt;&gt;</tt> marker. An alternate style, "diff3", adds a <tt>|||||||</tt>
marker and the original text before the <tt>=======</tt> marker.
</p>
</dd>
<dt>
merge.log
</dt>
<dd>
<p>
Whether to include summaries of merged commits in newly created
merge commit messages. False by default.
</p>
</dd>
<dt>
merge.renameLimit
</dt>
<dd>
<p>
The number of files to consider when performing rename detection
during a merge; if not specified, defaults to the value of
diff.renameLimit.
</p>
</dd>
<dt>
merge.stat
</dt>
<dd>
<p>
Whether to print the diffstat between ORIG_HEAD and the merge result
at the end of the merge. True by default.
</p>
</dd>
<dt>
merge.tool
</dt>
<dd>
<p>
Controls which merge resolution program is used by
<a href="git-mergetool.html">git-mergetool(1)</a>. Valid built-in values are: "kdiff3",
"tkdiff", "meld", "xxdiff", "emerge", "vimdiff", "gvimdiff",
"diffuse", "ecmerge", "tortoisemerge", and
"opendiff". Any other value is treated is custom merge tool
and there must be a corresponding mergetool.&lt;tool&gt;.cmd option.
</p>
</dd>
<dt>
merge.verbosity
</dt>
<dd>
<p>
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 <em>GIT_MERGE_VERBOSITY</em> environment variable.
</p>
</dd>
<dt>
merge.&lt;driver&gt;.name
</dt>
<dd>
<p>
Defines a human-readable name for a custom low-level
merge driver. See <a href="gitattributes.html">gitattributes(5)</a> for details.
</p>
</dd>
<dt>
merge.&lt;driver&gt;.driver
</dt>
<dd>
<p>
Defines the command that implements a custom low-level
merge driver. See <a href="gitattributes.html">gitattributes(5)</a> for details.
</p>
</dd>
<dt>
merge.&lt;driver&gt;.recursive
</dt>
<dd>
<p>
Names a low-level merge driver to be used when
performing an internal merge between common ancestors.
See <a href="gitattributes.html">gitattributes(5)</a> for details.
</p>
</dd>
<dt>
branch.&lt;name&gt;.mergeoptions
</dt>
<dd>
<p>
Sets default options for merging into branch &lt;name&gt;. The syntax and
supported options are equal to that of <em>git-merge</em>, but option values
containing whitespace characters are currently not supported.
</p>
</dd>
</dl></div>
</div>
<h2 id="_how_merge_works">HOW MERGE WORKS</h2>
<div class="sectionbody">
<div class="para"><p>A merge is always between the current <tt>HEAD</tt> and one or more
commits (usually, branch head or tag), and the index file must
match the tree of <tt>HEAD</tt> commit (i.e. the contents of the last commit)
when it starts out. In other words, <tt>git diff --cached HEAD</tt> must
report no changes. (One exception is when the changed index
entries are already in the same state that would result from
the merge anyway.)</p></div>
<div class="para"><p>Three kinds of merge can happen:</p></div>
<div class="ilist"><ul>
<li>
<p>
The merged commit is already contained in <tt>HEAD</tt>. This is the
simplest case, called "Already up-to-date."
</p>
</li>
<li>
<p>
<tt>HEAD</tt> is already contained in the merged commit. This is the
most common case especially when invoked from <em>git pull</em>:
you are tracking an upstream repository, have committed no local
changes and now you want to update to a newer upstream revision.
Your <tt>HEAD</tt> (and the index) is updated to point at the merged
commit, without creating an extra merge commit. This is
called "Fast-forward".
</p>
</li>
<li>
<p>
Both the merged commit and <tt>HEAD</tt> are independent and must be
tied together by a merge commit that has both of them as its parents.
The rest of this section describes this "True merge" case.
</p>
</li>
</ul></div>
<div class="para"><p>The chosen merge strategy merges the two commits into a single
new source tree.
When things merge cleanly, this is what happens:</p></div>
<div class="olist"><ol>
<li>
<p>
The results are updated both in the index file and in your
working tree;
</p>
</li>
<li>
<p>
Index file is written out as a tree;
</p>
</li>
<li>
<p>
The tree gets committed; and
</p>
</li>
<li>
<p>
The <tt>HEAD</tt> pointer gets advanced.
</p>
</li>
</ol></div>
<div class="para"><p>Because of 2., we require that the original state of the index
file matches exactly the current <tt>HEAD</tt> commit; otherwise we
will write out your local changes already registered in your
index file along with the merge result, which is not good.
Because 1. involves only those paths differing between your
branch and the remote branch you are pulling from during the
merge (which is typically a fraction of the whole tree), you can
have local modifications in your working tree as long as they do
not overlap with what the merge updates.</p></div>
<div class="para"><p>When there are conflicts, the following happens:</p></div>
<div class="olist"><ol>
<li>
<p>
<tt>HEAD</tt> stays the same.
</p>
</li>
<li>
<p>
Cleanly merged paths are updated both in the index file and
in your working tree.
</p>
</li>
<li>
<p>
For conflicting paths, the index file records up to three
versions; stage1 stores the version from the common ancestor,
stage2 from <tt>HEAD</tt>, and stage3 from the remote branch (you
can inspect the stages with <tt>git ls-files -u</tt>). The working
tree files contain the result of the "merge" program; i.e. 3-way
merge results with familiar conflict markers <tt>&lt;&lt;&lt; === &gt;&gt;&gt;</tt>.
</p>
</li>
<li>
<p>
No other changes are done. 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 <tt>HEAD</tt>.
</p>
</li>
</ol></div>
</div>
<h2 id="_how_conflicts_are_presented">HOW CONFLICTS ARE PRESENTED</h2>
<div class="sectionbody">
<div class="para"><p>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.</p></div>
<div class="para"><p>By default, git uses the same style as that is used by "merge" program
from the RCS suite to present such a conflicted hunk, like this:</p></div>
<div class="listingblock">
<div class="content">
<pre><tt>Here are lines that are either unchanged from the common
ancestor, or cleanly resolved because only one side changed.
&lt;&lt;&lt;&lt;&lt;&lt;&lt; yours:sample.txt
Conflict resolution is hard;
let's go shopping.
=======
Git makes conflict resolution easy.
&gt;&gt;&gt;&gt;&gt;&gt;&gt; theirs:sample.txt
And here is another line that is cleanly resolved or unmodified.</tt></pre>
</div></div>
<div class="para"><p>The area where a pair of conflicting changes happened is marked with markers
<tt>&lt;&lt;&lt;&lt;&lt;&lt;&lt;</tt>, <tt>=======</tt>, and <tt>&gt;&gt;&gt;&gt;&gt;&gt;&gt;</tt>. The part before the <tt>=======</tt>
is typically your side, and the part afterwards is typically their side.</p></div>
<div class="para"><p>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.</p></div>
<div class="para"><p>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:</p></div>
<div class="listingblock">
<div class="content">
<pre><tt>Here are lines that are either unchanged from the common
ancestor, or cleanly resolved because only one side changed.
&lt;&lt;&lt;&lt;&lt;&lt;&lt; yours:sample.txt
Conflict resolution is hard;
let's go shopping.
|||||||
Conflict resolution is hard.
=======
Git makes conflict resolution easy.
&gt;&gt;&gt;&gt;&gt;&gt;&gt; theirs:sample.txt
And here is another line that is cleanly resolved or unmodified.</tt></pre>
</div></div>
<div class="para"><p>In addition to the <tt>&lt;&lt;&lt;&lt;&lt;&lt;&lt;</tt>, <tt>=======</tt>, and <tt>&gt;&gt;&gt;&gt;&gt;&gt;&gt;</tt> markers, it uses
another <tt>|||||||</tt> 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.</p></div>
</div>
<h2 id="_how_to_resolve_conflicts">HOW TO RESOLVE CONFLICTS</h2>
<div class="sectionbody">
<div class="para"><p>After seeing a conflict, you can do two things:</p></div>
<div class="ilist"><ul>
<li>
<p>
Decide not to merge. The only clean-ups you need are to reset
the index file to the <tt>HEAD</tt> commit to reverse 2. and to clean
up working tree changes made by 2. and 3.; <em>git-reset --hard</em> can
be used for this.
</p>
</li>
<li>
<p>
Resolve the conflicts. Git will mark the conflicts in
the working tree. Edit the files into shape and
<em>git-add</em> them to the index. Use <em>git-commit</em> to seal the deal.
</p>
</li>
</ul></div>
<div class="para"><p>You can work through the conflict with a number of tools:</p></div>
<div class="ilist"><ul>
<li>
<p>
Use a mergetool. <em>git mergetool</em> to launch a graphical
mergetool which will work you through the merge.
</p>
</li>
<li>
<p>
Look at the diffs. <em>git diff</em> will show a three-way diff,
highlighting changes from both the HEAD and remote versions.
</p>
</li>
<li>
<p>
Look at the diffs on their own. <em>git log --merge -p &lt;path&gt;</em>
will show diffs first for the HEAD version and then the
remote version.
</p>
</li>
<li>
<p>
Look at the originals. <em>git show :1:filename</em> shows the
common ancestor, <em>git show :2:filename</em> shows the HEAD
version and <em>git show :3:filename</em> shows the remote version.
</p>
</li>
</ul></div>
</div>
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="para"><p><a href="git-fmt-merge-msg.html">git-fmt-merge-msg(1)</a>, <a href="git-pull.html">git-pull(1)</a>,
<a href="gitattributes.html">gitattributes(5)</a>,
<a href="git-reset.html">git-reset(1)</a>,
<a href="git-diff.html">git-diff(1)</a>, <a href="git-ls-files.html">git-ls-files(1)</a>,
<a href="git-add.html">git-add(1)</a>, <a href="git-rm.html">git-rm(1)</a>,
<a href="git-mergetool.html">git-mergetool(1)</a></p></div>
</div>
<h2 id="_author">Author</h2>
<div class="sectionbody">
<div class="para"><p>Written by Junio C Hamano &lt;gitster@pobox.com&gt;</p></div>
</div>
<h2 id="_documentation">Documentation</h2>
<div class="sectionbody">
<div class="para"><p>Documentation by Junio C Hamano and the git-list &lt;git@vger.kernel.org&gt;.</p></div>
</div>
<h2 id="_git">GIT</h2>
<div class="sectionbody">
<div class="para"><p>Part of the <a href="git.html">git(1)</a> suite</p></div>
</div>
<div id="footer">
<div id="footer-text">
Last updated 2009-04-18 06:17:32 UTC
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