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