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0f69be53 JH |
1 | git-merge(1) |
2 | ============ | |
0f69be53 JH |
3 | |
4 | NAME | |
5 | ---- | |
c3f0baac | 6 | git-merge - Join two or more development histories together |
0f69be53 JH |
7 | |
8 | ||
9 | SYNOPSIS | |
10 | -------- | |
17bcdad3 | 11 | [verse] |
f8246281 | 12 | 'git merge' [-n] [--stat] [--no-commit] [--squash] [--[no-]edit] |
340f2c5e | 13 | [-s <strategy>] [-X <strategy-option>] [-S[<keyid>]] |
09c2cb87 | 14 | [--[no-]allow-unrelated-histories] |
920f22e6 | 15 | [--[no-]rerere-autoupdate] [-m <msg>] [-F <file>] [<commit>...] |
35d2fffd | 16 | 'git merge' --abort |
367ff694 | 17 | 'git merge' --continue |
0f69be53 JH |
18 | |
19 | DESCRIPTION | |
20 | ----------- | |
b40bb374 JN |
21 | Incorporates changes from the named commits (since the time their |
22 | histories diverged from the current branch) into the current | |
23 | branch. This command is used by 'git pull' to incorporate changes | |
24 | from another repository and can be used by hand to merge changes | |
25 | from one branch into another. | |
26 | ||
27 | Assume the following history exists and the current branch is | |
28 | "`master`": | |
29 | ||
30 | ------------ | |
31 | A---B---C topic | |
32 | / | |
33 | D---E---F---G master | |
34 | ------------ | |
35 | ||
36 | Then "`git merge topic`" will replay the changes made on the | |
37 | `topic` branch since it diverged from `master` (i.e., `E`) until | |
38 | its current commit (`C`) on top of `master`, and record the result | |
39 | in a new commit along with the names of the two parent commits and | |
40 | a log message from the user describing the changes. | |
41 | ||
42 | ------------ | |
43 | A---B---C topic | |
44 | / \ | |
45 | D---E---F---G---H master | |
46 | ------------ | |
0f69be53 | 47 | |
b4391657 | 48 | The second syntax ("`git merge --abort`") can only be run after the |
35d2fffd JH |
49 | merge has resulted in conflicts. 'git merge --abort' will abort the |
50 | merge process and try to reconstruct the pre-merge state. However, | |
51 | if there were uncommitted changes when the merge started (and | |
52 | especially if those changes were further modified after the merge | |
53 | was started), 'git merge --abort' will in some cases be unable to | |
54 | reconstruct the original (pre-merge) changes. Therefore: | |
55 | ||
76b80cdf MM |
56 | *Warning*: Running 'git merge' with non-trivial uncommitted changes is |
57 | discouraged: while possible, it may leave you in a state that is hard to | |
e330d8ca | 58 | back out of in the case of a conflict. |
dee48c3c | 59 | |
28cb0602 | 60 | The third syntax ("`git merge --continue`") can only be run after the |
367ff694 | 61 | merge has resulted in conflicts. |
0f69be53 JH |
62 | |
63 | OPTIONS | |
64 | ------- | |
93d69d86 | 65 | include::merge-options.txt[] |
0f69be53 | 66 | |
dee48c3c | 67 | -m <msg>:: |
0f8a02c6 | 68 | Set the commit message to be used for the merge commit (in |
f0ecac2b | 69 | case one is created). |
af77aee9 NP |
70 | + |
71 | If `--log` is specified, a shortlog of the commits being merged | |
72 | will be appended to the specified message. | |
73 | + | |
74 | The 'git fmt-merge-msg' command can be | |
75 | used to give a good default for automated 'git merge' | |
561d2b79 | 76 | invocations. The automated message can include the branch description. |
3c64314c | 77 | |
920f22e6 JS |
78 | -F <file>:: |
79 | --file=<file>:: | |
80 | Read the commit message to be used for the merge commit (in | |
81 | case one is created). | |
82 | + | |
83 | If `--log` is specified, a shortlog of the commits being merged | |
84 | will be appended to the specified message. | |
85 | ||
0460ed2c | 86 | --[no-]rerere-autoupdate:: |
cb6020bb JH |
87 | Allow the rerere mechanism to update the index with the |
88 | result of auto-conflict resolution if possible. | |
89 | ||
35d2fffd JH |
90 | --abort:: |
91 | Abort the current conflict resolution process, and | |
92 | try to reconstruct the pre-merge state. | |
93 | + | |
94 | If there were uncommitted worktree changes present when the merge | |
95 | started, 'git merge --abort' will in some cases be unable to | |
96 | reconstruct these changes. It is therefore recommended to always | |
97 | commit or stash your changes before running 'git merge'. | |
98 | + | |
99 | 'git merge --abort' is equivalent to 'git reset --merge' when | |
100 | `MERGE_HEAD` is present. | |
101 | ||
367ff694 CP |
102 | --continue:: |
103 | After a 'git merge' stops due to conflicts you can conclude the | |
104 | merge by running 'git merge --continue' (see "HOW TO RESOLVE | |
105 | CONFLICTS" section below). | |
106 | ||
57bddb11 TR |
107 | <commit>...:: |
108 | Commits, usually other branch heads, to merge into our branch. | |
93e535a5 JH |
109 | Specifying more than one commit will create a merge with |
110 | more than two parents (affectionately called an Octopus merge). | |
111 | + | |
a01f7f2b FC |
112 | If no commit is given from the command line, merge the remote-tracking |
113 | branches that the current branch is configured to use as its upstream. | |
93e535a5 | 114 | See also the configuration section of this manual page. |
74e8bc59 JH |
115 | + |
116 | When `FETCH_HEAD` (and no other commit) is specified, the branches | |
117 | recorded in the `.git/FETCH_HEAD` file by the previous invocation | |
118 | of `git fetch` for merging are merged to the current branch. | |
0f69be53 | 119 | |
bb73d73c | 120 | |
30f2bade JN |
121 | PRE-MERGE CHECKS |
122 | ---------------- | |
0f69be53 | 123 | |
30f2bade JN |
124 | Before applying outside changes, you should get your own work in |
125 | good shape and committed locally, so it will not be clobbered if | |
126 | there are conflicts. See also linkgit:git-stash[1]. | |
127 | 'git pull' and 'git merge' will stop without doing anything when | |
128 | local uncommitted changes overlap with files that 'git pull'/'git | |
129 | merge' may need to update. | |
3ae854c3 | 130 | |
30f2bade JN |
131 | To avoid recording unrelated changes in the merge commit, |
132 | 'git pull' and 'git merge' will also abort if there are any changes | |
55f39cf7 EN |
133 | registered in the index relative to the `HEAD` commit. (Special |
134 | narrow exceptions to this rule may exist depending on which merge | |
135 | strategy is in use, but generally, the index must match HEAD.) | |
dbddb714 | 136 | |
30f2bade | 137 | If all named commits are already ancestors of `HEAD`, 'git merge' |
7560f547 | 138 | will exit early with the message "Already up to date." |
3ae854c3 | 139 | |
29280311 JN |
140 | FAST-FORWARD MERGE |
141 | ------------------ | |
142 | ||
143 | Often the current branch head is an ancestor of the named commit. | |
144 | This is the most common case especially when invoked from 'git | |
145 | pull': you are tracking an upstream repository, you have committed | |
146 | no local changes, and now you want to update to a newer upstream | |
147 | revision. In this case, a new commit is not needed to store the | |
148 | combined history; instead, the `HEAD` (along with the index) is | |
149 | updated to point at the named commit, without creating an extra | |
150 | merge commit. | |
151 | ||
152 | This behavior can be suppressed with the `--no-ff` option. | |
ffb1a4be | 153 | |
ebef7e50 JN |
154 | TRUE MERGE |
155 | ---------- | |
c0be8aa0 | 156 | |
29280311 JN |
157 | Except in a fast-forward merge (see above), the branches to be |
158 | merged must be tied together by a merge commit that has both of them | |
159 | as its parents. | |
ffb1a4be | 160 | |
ebef7e50 JN |
161 | A merged version reconciling the changes from all branches to be |
162 | merged is committed, and your `HEAD`, index, and working tree are | |
163 | updated to it. It is possible to have modifications in the working | |
164 | tree as long as they do not overlap; the update will preserve them. | |
ffb1a4be | 165 | |
ebef7e50 JN |
166 | When it is not obvious how to reconcile the changes, the following |
167 | happens: | |
ffb1a4be | 168 | |
ebef7e50 JN |
169 | 1. The `HEAD` pointer stays the same. |
170 | 2. The `MERGE_HEAD` ref is set to point to the other branch head. | |
171 | 3. Paths that merged cleanly are updated both in the index file and | |
ffb1a4be | 172 | in your working tree. |
ebef7e50 JN |
173 | 4. For conflicting paths, the index file records up to three |
174 | versions: stage 1 stores the version from the common ancestor, | |
175 | stage 2 from `HEAD`, and stage 3 from `MERGE_HEAD` (you | |
b1889c36 | 176 | can inspect the stages with `git ls-files -u`). The working |
29b802aa | 177 | tree files contain the result of the "merge" program; i.e. 3-way |
ebef7e50 JN |
178 | merge results with familiar conflict markers `<<<` `===` `>>>`. |
179 | 5. No other changes are made. In particular, the local | |
ffb1a4be JH |
180 | modifications you had before you started merge will stay the |
181 | same and the index entries for them stay as they were, | |
182 | i.e. matching `HEAD`. | |
183 | ||
ed4a6baa | 184 | If you tried a merge which resulted in complex conflicts and |
35d2fffd | 185 | want to start over, you can recover with `git merge --abort`. |
ed4a6baa | 186 | |
77c72780 JH |
187 | MERGING TAG |
188 | ----------- | |
189 | ||
190 | When merging an annotated (and possibly signed) tag, Git always | |
191 | creates a merge commit even if a fast-forward merge is possible, and | |
192 | the commit message template is prepared with the tag message. | |
193 | Additionally, if the tag is signed, the signature check is reported | |
194 | as a comment in the message template. See also linkgit:git-tag[1]. | |
195 | ||
196 | When you want to just integrate with the work leading to the commit | |
197 | that happens to be tagged, e.g. synchronizing with an upstream | |
198 | release point, you may not want to make an unnecessary merge commit. | |
199 | ||
200 | In such a case, you can "unwrap" the tag yourself before feeding it | |
201 | to `git merge`, or pass `--ff-only` when you do not have any work on | |
202 | your own. e.g. | |
203 | ||
e45bda87 | 204 | ---- |
77c72780 JH |
205 | git fetch origin |
206 | git merge v1.2.3^0 | |
207 | git merge --ff-only v1.2.3 | |
e45bda87 | 208 | ---- |
77c72780 JH |
209 | |
210 | ||
70a3f897 JH |
211 | HOW CONFLICTS ARE PRESENTED |
212 | --------------------------- | |
213 | ||
214 | During a merge, the working tree files are updated to reflect the result | |
215 | of the merge. Among the changes made to the common ancestor's version, | |
216 | non-overlapping ones (that is, you changed an area of the file while the | |
217 | other side left that area intact, or vice versa) are incorporated in the | |
218 | final result verbatim. When both sides made changes to the same area, | |
2de9b711 | 219 | however, Git cannot randomly pick one side over the other, and asks you to |
70a3f897 JH |
220 | resolve it by leaving what both sides did to that area. |
221 | ||
2de9b711 | 222 | By default, Git uses the same style as the one used by the "merge" program |
70a3f897 JH |
223 | from the RCS suite to present such a conflicted hunk, like this: |
224 | ||
225 | ------------ | |
226 | Here are lines that are either unchanged from the common | |
227 | ancestor, or cleanly resolved because only one side changed. | |
228 | <<<<<<< yours:sample.txt | |
229 | Conflict resolution is hard; | |
230 | let's go shopping. | |
231 | ======= | |
232 | Git makes conflict resolution easy. | |
233 | >>>>>>> theirs:sample.txt | |
234 | And here is another line that is cleanly resolved or unmodified. | |
235 | ------------ | |
236 | ||
29b802aa | 237 | The area where a pair of conflicting changes happened is marked with markers |
dcb11263 | 238 | `<<<<<<<`, `=======`, and `>>>>>>>`. The part before the `=======` |
29b802aa | 239 | is typically your side, and the part afterwards is typically their side. |
70a3f897 | 240 | |
29b802aa RW |
241 | The default format does not show what the original said in the conflicting |
242 | area. You cannot tell how many lines are deleted and replaced with | |
243 | Barbie's remark on your side. The only thing you can tell is that your | |
70a3f897 JH |
244 | side wants to say it is hard and you'd prefer to go shopping, while the |
245 | other side wants to claim it is easy. | |
246 | ||
da0005b8 | 247 | An alternative style can be used by setting the "merge.conflictStyle" |
70a3f897 JH |
248 | configuration variable to "diff3". In "diff3" style, the above conflict |
249 | may look like this: | |
250 | ||
251 | ------------ | |
252 | Here are lines that are either unchanged from the common | |
253 | ancestor, or cleanly resolved because only one side changed. | |
254 | <<<<<<< yours:sample.txt | |
255 | Conflict resolution is hard; | |
256 | let's go shopping. | |
257 | ||||||| | |
258 | Conflict resolution is hard. | |
259 | ======= | |
260 | Git makes conflict resolution easy. | |
261 | >>>>>>> theirs:sample.txt | |
262 | And here is another line that is cleanly resolved or unmodified. | |
263 | ------------ | |
264 | ||
dcb11263 CJ |
265 | In addition to the `<<<<<<<`, `=======`, and `>>>>>>>` markers, it uses |
266 | another `|||||||` marker that is followed by the original text. You can | |
70a3f897 JH |
267 | tell that the original just stated a fact, and your side simply gave in to |
268 | that statement and gave up, while the other side tried to have a more | |
269 | positive attitude. You can sometimes come up with a better resolution by | |
270 | viewing the original. | |
271 | ||
272 | ||
273 | HOW TO RESOLVE CONFLICTS | |
274 | ------------------------ | |
275 | ||
ffb1a4be JH |
276 | After seeing a conflict, you can do two things: |
277 | ||
29b802aa | 278 | * Decide not to merge. The only clean-ups you need are to reset |
ffb1a4be | 279 | the index file to the `HEAD` commit to reverse 2. and to clean |
35d2fffd JH |
280 | up working tree changes made by 2. and 3.; `git merge --abort` |
281 | can be used for this. | |
ffb1a4be | 282 | |
34ad1afa DH |
283 | * Resolve the conflicts. Git will mark the conflicts in |
284 | the working tree. Edit the files into shape and | |
e2de82f2 MG |
285 | 'git add' them to the index. Use 'git commit' or |
286 | 'git merge --continue' to seal the deal. The latter command | |
287 | checks whether there is a (interrupted) merge in progress | |
288 | before calling 'git commit'. | |
ffb1a4be | 289 | |
34ad1afa DH |
290 | You can work through the conflict with a number of tools: |
291 | ||
ca768288 | 292 | * Use a mergetool. `git mergetool` to launch a graphical |
34ad1afa DH |
293 | mergetool which will work you through the merge. |
294 | ||
ca768288 | 295 | * Look at the diffs. `git diff` will show a three-way diff, |
3588cf94 JN |
296 | highlighting changes from both the `HEAD` and `MERGE_HEAD` |
297 | versions. | |
34ad1afa | 298 | |
3588cf94 JN |
299 | * Look at the diffs from each branch. `git log --merge -p <path>` |
300 | will show diffs first for the `HEAD` version and then the | |
301 | `MERGE_HEAD` version. | |
34ad1afa | 302 | |
ca768288 | 303 | * Look at the originals. `git show :1:filename` shows the |
3588cf94 JN |
304 | common ancestor, `git show :2:filename` shows the `HEAD` |
305 | version, and `git show :3:filename` shows the `MERGE_HEAD` | |
306 | version. | |
ffb1a4be | 307 | |
d504f697 CB |
308 | |
309 | EXAMPLES | |
310 | -------- | |
311 | ||
312 | * Merge branches `fixes` and `enhancements` on top of | |
313 | the current branch, making an octopus merge: | |
314 | + | |
315 | ------------------------------------------------ | |
316 | $ git merge fixes enhancements | |
317 | ------------------------------------------------ | |
318 | ||
319 | * Merge branch `obsolete` into the current branch, using `ours` | |
320 | merge strategy: | |
321 | + | |
322 | ------------------------------------------------ | |
323 | $ git merge -s ours obsolete | |
324 | ------------------------------------------------ | |
325 | ||
326 | * Merge branch `maint` into the current branch, but do not make | |
327 | a new commit automatically: | |
328 | + | |
329 | ------------------------------------------------ | |
330 | $ git merge --no-commit maint | |
331 | ------------------------------------------------ | |
332 | + | |
333 | This can be used when you want to include further changes to the | |
334 | merge, or want to write your own merge commit message. | |
335 | + | |
336 | You should refrain from abusing this option to sneak substantial | |
337 | changes into a merge commit. Small fixups like bumping | |
338 | release/version name would be acceptable. | |
339 | ||
340 | ||
a4081bac JN |
341 | include::merge-strategies.txt[] |
342 | ||
35e9d630 JN |
343 | CONFIGURATION |
344 | ------------- | |
7fb5ab4a | 345 | include::config/merge.txt[] |
35e9d630 | 346 | |
da0005b8 | 347 | branch.<name>.mergeOptions:: |
35e9d630 JN |
348 | Sets default options for merging into branch <name>. The syntax and |
349 | supported options are the same as those of 'git merge', but option | |
350 | values containing whitespace characters are currently not supported. | |
351 | ||
3c64314c PB |
352 | SEE ALSO |
353 | -------- | |
5162e697 | 354 | linkgit:git-fmt-merge-msg[1], linkgit:git-pull[1], |
483bc4f0 JN |
355 | linkgit:gitattributes[5], |
356 | linkgit:git-reset[1], | |
357 | linkgit:git-diff[1], linkgit:git-ls-files[1], | |
358 | linkgit:git-add[1], linkgit:git-rm[1], | |
359 | linkgit:git-mergetool[1] | |
3c64314c | 360 | |
0f69be53 JH |
361 | GIT |
362 | --- | |
9e1f0a85 | 363 | Part of the linkgit:git[1] suite |