| blob | 092529c619e29cfa1c0959358d4671ff1cba1144 |
1 git-merge(1)
2 ============
4 NAME
5 ----
6 git-merge - Join two or more development histories together
9 SYNOPSIS
10 --------
11 [verse]
12 'git merge' [-n] [--stat] [--no-commit] [--squash] [--[no-]edit]
13 [--no-verify] [-s <strategy>] [-X <strategy-option>] [-S[<keyid>]]
14 [--[no-]allow-unrelated-histories]
15 [--[no-]rerere-autoupdate] [-m <msg>] [-F <file>] [<commit>...]
16 'git merge' (--continue | --abort | --quit)
18 DESCRIPTION
19 -----------
20 Incorporates changes from the named commits (since the time their
21 histories diverged from the current branch) into the current
22 branch. This command is used by 'git pull' to incorporate changes
23 from another repository and can be used by hand to merge changes
24 from one branch into another.
26 Assume the following history exists and the current branch is
27 "`master`":
29 ------------
30 A---B---C topic
31 /
32 D---E---F---G master
33 ------------
35 Then "`git merge topic`" will replay the changes made on the
36 `topic` branch since it diverged from `master` (i.e., `E`) until
37 its current commit (`C`) on top of `master`, and record the result
38 in a new commit along with the names of the two parent commits and
39 a log message from the user describing the changes.
41 ------------
42 A---B---C topic
43 / \
44 D---E---F---G---H master
45 ------------
47 The second syntax ("`git merge --abort`") can only be run after the
48 merge has resulted in conflicts. 'git merge --abort' will abort the
49 merge process and try to reconstruct the pre-merge state. However,
50 if there were uncommitted changes when the merge started (and
51 especially if those changes were further modified after the merge
52 was started), 'git merge --abort' will in some cases be unable to
53 reconstruct the original (pre-merge) changes. Therefore:
55 *Warning*: Running 'git merge' with non-trivial uncommitted changes is
56 discouraged: while possible, it may leave you in a state that is hard to
57 back out of in the case of a conflict.
59 The third syntax ("`git merge --continue`") can only be run after the
60 merge has resulted in conflicts.
62 OPTIONS
63 -------
64 include::merge-options.txt[]
66 -m <msg>::
67 Set the commit message to be used for the merge commit (in
68 case one is created).
69 +
70 If `--log` is specified, a shortlog of the commits being merged
71 will be appended to the specified message.
72 +
73 The 'git fmt-merge-msg' command can be
74 used to give a good default for automated 'git merge'
75 invocations. The automated message can include the branch description.
77 -F <file>::
78 --file=<file>::
79 Read the commit message to be used for the merge commit (in
80 case one is created).
81 +
82 If `--log` is specified, a shortlog of the commits being merged
83 will be appended to the specified message.
85 --rerere-autoupdate::
86 --no-rerere-autoupdate::
87 Allow the rerere mechanism to update the index with the
88 result of auto-conflict resolution if possible.
90 --overwrite-ignore::
91 --no-overwrite-ignore::
92 Silently overwrite ignored files from the merge result. This
93 is the default behavior. Use `--no-overwrite-ignore` to abort.
95 --abort::
96 Abort the current conflict resolution process, and
97 try to reconstruct the pre-merge state.
98 +
99 If there were uncommitted worktree changes present when the merge
100 started, 'git merge --abort' will in some cases be unable to
101 reconstruct these changes. It is therefore recommended to always
102 commit or stash your changes before running 'git merge'.
103 +
104 'git merge --abort' is equivalent to 'git reset --merge' when
105 `MERGE_HEAD` is present.
107 --quit::
108 Forget about the current merge in progress. Leave the index
109 and the working tree as-is.
111 --continue::
112 After a 'git merge' stops due to conflicts you can conclude the
113 merge by running 'git merge --continue' (see "HOW TO RESOLVE
114 CONFLICTS" section below).
116 <commit>...::
117 Commits, usually other branch heads, to merge into our branch.
118 Specifying more than one commit will create a merge with
119 more than two parents (affectionately called an Octopus merge).
120 +
121 If no commit is given from the command line, merge the remote-tracking
122 branches that the current branch is configured to use as its upstream.
123 See also the configuration section of this manual page.
124 +
125 When `FETCH_HEAD` (and no other commit) is specified, the branches
126 recorded in the `.git/FETCH_HEAD` file by the previous invocation
127 of `git fetch` for merging are merged to the current branch.
130 PRE-MERGE CHECKS
131 ----------------
133 Before applying outside changes, you should get your own work in
134 good shape and committed locally, so it will not be clobbered if
135 there are conflicts. See also linkgit:git-stash[1].
136 'git pull' and 'git merge' will stop without doing anything when
137 local uncommitted changes overlap with files that 'git pull'/'git
138 merge' may need to update.
140 To avoid recording unrelated changes in the merge commit,
141 'git pull' and 'git merge' will also abort if there are any changes
142 registered in the index relative to the `HEAD` commit. (Special
143 narrow exceptions to this rule may exist depending on which merge
144 strategy is in use, but generally, the index must match HEAD.)
146 If all named commits are already ancestors of `HEAD`, 'git merge'
147 will exit early with the message "Already up to date."
149 FAST-FORWARD MERGE
150 ------------------
152 Often the current branch head is an ancestor of the named commit.
153 This is the most common case especially when invoked from 'git
154 pull': you are tracking an upstream repository, you have committed
155 no local changes, and now you want to update to a newer upstream
156 revision. In this case, a new commit is not needed to store the
157 combined history; instead, the `HEAD` (along with the index) is
158 updated to point at the named commit, without creating an extra
159 merge commit.
161 This behavior can be suppressed with the `--no-ff` option.
163 TRUE MERGE
164 ----------
166 Except in a fast-forward merge (see above), the branches to be
167 merged must be tied together by a merge commit that has both of them
168 as its parents.
170 A merged version reconciling the changes from all branches to be
171 merged is committed, and your `HEAD`, index, and working tree are
172 updated to it. It is possible to have modifications in the working
173 tree as long as they do not overlap; the update will preserve them.
175 When it is not obvious how to reconcile the changes, the following
176 happens:
178 1. The `HEAD` pointer stays the same.
179 2. The `MERGE_HEAD` ref is set to point to the other branch head.
180 3. Paths that merged cleanly are updated both in the index file and
181 in your working tree.
182 4. For conflicting paths, the index file records up to three
183 versions: stage 1 stores the version from the common ancestor,
184 stage 2 from `HEAD`, and stage 3 from `MERGE_HEAD` (you
185 can inspect the stages with `git ls-files -u`). The working
186 tree files contain the result of the "merge" program; i.e. 3-way
187 merge results with familiar conflict markers `<<<` `===` `>>>`.
188 5. No other changes are made. In particular, the local
189 modifications you had before you started merge will stay the
190 same and the index entries for them stay as they were,
191 i.e. matching `HEAD`.
193 If you tried a merge which resulted in complex conflicts and
194 want to start over, you can recover with `git merge --abort`.
196 MERGING TAG
197 -----------
199 When merging an annotated (and possibly signed) tag, Git always
200 creates a merge commit even if a fast-forward merge is possible, and
201 the commit message template is prepared with the tag message.
202 Additionally, if the tag is signed, the signature check is reported
203 as a comment in the message template. See also linkgit:git-tag[1].
205 When you want to just integrate with the work leading to the commit
206 that happens to be tagged, e.g. synchronizing with an upstream
207 release point, you may not want to make an unnecessary merge commit.
209 In such a case, you can "unwrap" the tag yourself before feeding it
210 to `git merge`, or pass `--ff-only` when you do not have any work on
211 your own. e.g.
213 ----
214 git fetch origin
215 git merge v1.2.3^0
216 git merge --ff-only v1.2.3
217 ----
220 HOW CONFLICTS ARE PRESENTED
221 ---------------------------
223 During a merge, the working tree files are updated to reflect the result
224 of the merge. Among the changes made to the common ancestor's version,
225 non-overlapping ones (that is, you changed an area of the file while the
226 other side left that area intact, or vice versa) are incorporated in the
227 final result verbatim. When both sides made changes to the same area,
228 however, Git cannot randomly pick one side over the other, and asks you to
229 resolve it by leaving what both sides did to that area.
231 By default, Git uses the same style as the one used by the "merge" program
232 from the RCS suite to present such a conflicted hunk, like this:
234 ------------
235 Here are lines that are either unchanged from the common
236 ancestor, or cleanly resolved because only one side changed.
237 <<<<<<< yours:sample.txt
238 Conflict resolution is hard;
239 let's go shopping.
240 =======
241 Git makes conflict resolution easy.
242 >>>>>>> theirs:sample.txt
243 And here is another line that is cleanly resolved or unmodified.
244 ------------
246 The area where a pair of conflicting changes happened is marked with markers
247 `<<<<<<<`, `=======`, and `>>>>>>>`. The part before the `=======`
248 is typically your side, and the part afterwards is typically their side.
250 The default format does not show what the original said in the conflicting
251 area. You cannot tell how many lines are deleted and replaced with
252 Barbie's remark on your side. The only thing you can tell is that your
253 side wants to say it is hard and you'd prefer to go shopping, while the
254 other side wants to claim it is easy.
256 An alternative style can be used by setting the "merge.conflictStyle"
257 configuration variable to "diff3". In "diff3" style, the above conflict
258 may look like this:
260 ------------
261 Here are lines that are either unchanged from the common
262 ancestor, or cleanly resolved because only one side changed.
263 <<<<<<< yours:sample.txt
264 Conflict resolution is hard;
265 let's go shopping.
266 |||||||
267 Conflict resolution is hard.
268 =======
269 Git makes conflict resolution easy.
270 >>>>>>> theirs:sample.txt
271 And here is another line that is cleanly resolved or unmodified.
272 ------------
274 In addition to the `<<<<<<<`, `=======`, and `>>>>>>>` markers, it uses
275 another `|||||||` marker that is followed by the original text. You can
276 tell that the original just stated a fact, and your side simply gave in to
277 that statement and gave up, while the other side tried to have a more
278 positive attitude. You can sometimes come up with a better resolution by
279 viewing the original.
282 HOW TO RESOLVE CONFLICTS
283 ------------------------
285 After seeing a conflict, you can do two things:
287 * Decide not to merge. The only clean-ups you need are to reset
288 the index file to the `HEAD` commit to reverse 2. and to clean
289 up working tree changes made by 2. and 3.; `git merge --abort`
290 can be used for this.
292 * Resolve the conflicts. Git will mark the conflicts in
293 the working tree. Edit the files into shape and
294 'git add' them to the index. Use 'git commit' or
295 'git merge --continue' to seal the deal. The latter command
296 checks whether there is a (interrupted) merge in progress
297 before calling 'git commit'.
299 You can work through the conflict with a number of tools:
301 * Use a mergetool. `git mergetool` to launch a graphical
302 mergetool which will work you through the merge.
304 * Look at the diffs. `git diff` will show a three-way diff,
305 highlighting changes from both the `HEAD` and `MERGE_HEAD`
306 versions.
308 * Look at the diffs from each branch. `git log --merge -p <path>`
309 will show diffs first for the `HEAD` version and then the
310 `MERGE_HEAD` version.
312 * Look at the originals. `git show :1:filename` shows the
313 common ancestor, `git show :2:filename` shows the `HEAD`
314 version, and `git show :3:filename` shows the `MERGE_HEAD`
315 version.
318 EXAMPLES
319 --------
321 * Merge branches `fixes` and `enhancements` on top of
322 the current branch, making an octopus merge:
323 +
324 ------------------------------------------------
325 $ git merge fixes enhancements
326 ------------------------------------------------
328 * Merge branch `obsolete` into the current branch, using `ours`
329 merge strategy:
330 +
331 ------------------------------------------------
332 $ git merge -s ours obsolete
333 ------------------------------------------------
335 * Merge branch `maint` into the current branch, but do not make
336 a new commit automatically:
337 +
338 ------------------------------------------------
339 $ git merge --no-commit maint
340 ------------------------------------------------
341 +
342 This can be used when you want to include further changes to the
343 merge, or want to write your own merge commit message.
344 +
345 You should refrain from abusing this option to sneak substantial
346 changes into a merge commit. Small fixups like bumping
347 release/version name would be acceptable.
350 include::merge-strategies.txt[]
352 CONFIGURATION
353 -------------
354 include::config/merge.txt[]
356 branch.<name>.mergeOptions::
357 Sets default options for merging into branch <name>. The syntax and
358 supported options are the same as those of 'git merge', but option
359 values containing whitespace characters are currently not supported.
361 SEE ALSO
362 --------
363 linkgit:git-fmt-merge-msg[1], linkgit:git-pull[1],
364 linkgit:gitattributes[5],
365 linkgit:git-reset[1],
366 linkgit:git-diff[1], linkgit:git-ls-files[1],
367 linkgit:git-add[1], linkgit:git-rm[1],
368 linkgit:git-mergetool[1]
370 GIT
371 ---
372 Part of the linkgit:git[1] suite