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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] |
adda3c3b MB |
12 | 'git merge' [-n] [--stat] [--no-commit] [--squash] |
13 | [-s <strategy>] [-X <strategy-option>] | |
93e535a5 | 14 | [--[no-]rerere-autoupdate] [-m <msg>] [<commit>...] |
57bddb11 | 15 | 'git merge' <msg> HEAD <commit>... |
35d2fffd | 16 | 'git merge' --abort |
0f69be53 JH |
17 | |
18 | DESCRIPTION | |
19 | ----------- | |
b40bb374 JN |
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. | |
25 | ||
26 | Assume the following history exists and the current branch is | |
27 | "`master`": | |
28 | ||
29 | ------------ | |
30 | A---B---C topic | |
31 | / | |
32 | D---E---F---G master | |
33 | ------------ | |
34 | ||
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. | |
40 | ||
41 | ------------ | |
42 | A---B---C topic | |
43 | / \ | |
44 | D---E---F---G---H master | |
45 | ------------ | |
0f69be53 | 46 | |
57bddb11 | 47 | The second syntax (<msg> `HEAD` <commit>...) is supported for |
dee48c3c | 48 | historical reasons. Do not use it from the command line or in |
57bddb11 | 49 | new scripts. It is the same as `git merge -m <msg> <commit>...`. |
dee48c3c | 50 | |
35d2fffd JH |
51 | The third syntax ("`git merge --abort`") can only be run after the |
52 | merge has resulted in conflicts. 'git merge --abort' will abort the | |
53 | merge process and try to reconstruct the pre-merge state. However, | |
54 | if there were uncommitted changes when the merge started (and | |
55 | especially if those changes were further modified after the merge | |
56 | was started), 'git merge --abort' will in some cases be unable to | |
57 | reconstruct the original (pre-merge) changes. Therefore: | |
58 | ||
0b444cdb | 59 | *Warning*: Running 'git merge' with uncommitted changes is |
e330d8ca TR |
60 | discouraged: while possible, it leaves you in a state that is hard to |
61 | back out of in the case of a conflict. | |
dee48c3c | 62 | |
0f69be53 JH |
63 | |
64 | OPTIONS | |
65 | ------- | |
93d69d86 | 66 | include::merge-options.txt[] |
0f69be53 | 67 | |
dee48c3c | 68 | -m <msg>:: |
0f8a02c6 | 69 | Set the commit message to be used for the merge commit (in |
f0ecac2b | 70 | case one is created). |
af77aee9 NP |
71 | + |
72 | If `--log` is specified, a shortlog of the commits being merged | |
73 | will be appended to the specified message. | |
74 | + | |
75 | The 'git fmt-merge-msg' command can be | |
76 | used to give a good default for automated 'git merge' | |
77 | invocations. | |
3c64314c | 78 | |
cb6020bb JH |
79 | --rerere-autoupdate:: |
80 | --no-rerere-autoupdate:: | |
81 | Allow the rerere mechanism to update the index with the | |
82 | result of auto-conflict resolution if possible. | |
83 | ||
35d2fffd JH |
84 | --abort:: |
85 | Abort the current conflict resolution process, and | |
86 | try to reconstruct the pre-merge state. | |
87 | + | |
88 | If there were uncommitted worktree changes present when the merge | |
89 | started, 'git merge --abort' will in some cases be unable to | |
90 | reconstruct these changes. It is therefore recommended to always | |
91 | commit or stash your changes before running 'git merge'. | |
92 | + | |
93 | 'git merge --abort' is equivalent to 'git reset --merge' when | |
94 | `MERGE_HEAD` is present. | |
95 | ||
57bddb11 TR |
96 | <commit>...:: |
97 | Commits, usually other branch heads, to merge into our branch. | |
93e535a5 JH |
98 | Specifying more than one commit will create a merge with |
99 | more than two parents (affectionately called an Octopus merge). | |
100 | + | |
101 | If no commit is given from the command line, and if `merge.defaultToUpstream` | |
102 | configuration variable is set, merge the remote tracking branches | |
103 | that the current branch is configured to use as its upstream. | |
104 | See also the configuration section of this manual page. | |
0f69be53 | 105 | |
bb73d73c | 106 | |
30f2bade JN |
107 | PRE-MERGE CHECKS |
108 | ---------------- | |
0f69be53 | 109 | |
30f2bade JN |
110 | Before applying outside changes, you should get your own work in |
111 | good shape and committed locally, so it will not be clobbered if | |
112 | there are conflicts. See also linkgit:git-stash[1]. | |
113 | 'git pull' and 'git merge' will stop without doing anything when | |
114 | local uncommitted changes overlap with files that 'git pull'/'git | |
115 | merge' may need to update. | |
3ae854c3 | 116 | |
30f2bade JN |
117 | To avoid recording unrelated changes in the merge commit, |
118 | 'git pull' and 'git merge' will also abort if there are any changes | |
119 | registered in the index relative to the `HEAD` commit. (One | |
120 | exception is when the changed index entries are in the state that | |
121 | would result from the merge already.) | |
dbddb714 | 122 | |
30f2bade JN |
123 | If all named commits are already ancestors of `HEAD`, 'git merge' |
124 | will exit early with the message "Already up-to-date." | |
3ae854c3 | 125 | |
29280311 JN |
126 | FAST-FORWARD MERGE |
127 | ------------------ | |
128 | ||
129 | Often the current branch head is an ancestor of the named commit. | |
130 | This is the most common case especially when invoked from 'git | |
131 | pull': you are tracking an upstream repository, you have committed | |
132 | no local changes, and now you want to update to a newer upstream | |
133 | revision. In this case, a new commit is not needed to store the | |
134 | combined history; instead, the `HEAD` (along with the index) is | |
135 | updated to point at the named commit, without creating an extra | |
136 | merge commit. | |
137 | ||
138 | This behavior can be suppressed with the `--no-ff` option. | |
ffb1a4be | 139 | |
ebef7e50 JN |
140 | TRUE MERGE |
141 | ---------- | |
c0be8aa0 | 142 | |
29280311 JN |
143 | Except in a fast-forward merge (see above), the branches to be |
144 | merged must be tied together by a merge commit that has both of them | |
145 | as its parents. | |
ffb1a4be | 146 | |
ebef7e50 JN |
147 | A merged version reconciling the changes from all branches to be |
148 | merged is committed, and your `HEAD`, index, and working tree are | |
149 | updated to it. It is possible to have modifications in the working | |
150 | tree as long as they do not overlap; the update will preserve them. | |
ffb1a4be | 151 | |
ebef7e50 JN |
152 | When it is not obvious how to reconcile the changes, the following |
153 | happens: | |
ffb1a4be | 154 | |
ebef7e50 JN |
155 | 1. The `HEAD` pointer stays the same. |
156 | 2. The `MERGE_HEAD` ref is set to point to the other branch head. | |
157 | 3. Paths that merged cleanly are updated both in the index file and | |
ffb1a4be | 158 | in your working tree. |
ebef7e50 JN |
159 | 4. For conflicting paths, the index file records up to three |
160 | versions: stage 1 stores the version from the common ancestor, | |
161 | stage 2 from `HEAD`, and stage 3 from `MERGE_HEAD` (you | |
b1889c36 | 162 | can inspect the stages with `git ls-files -u`). The working |
29b802aa | 163 | tree files contain the result of the "merge" program; i.e. 3-way |
ebef7e50 JN |
164 | merge results with familiar conflict markers `<<<` `===` `>>>`. |
165 | 5. No other changes are made. In particular, the local | |
ffb1a4be JH |
166 | modifications you had before you started merge will stay the |
167 | same and the index entries for them stay as they were, | |
168 | i.e. matching `HEAD`. | |
169 | ||
ed4a6baa | 170 | If you tried a merge which resulted in complex conflicts and |
35d2fffd | 171 | want to start over, you can recover with `git merge --abort`. |
ed4a6baa | 172 | |
70a3f897 JH |
173 | HOW CONFLICTS ARE PRESENTED |
174 | --------------------------- | |
175 | ||
176 | During a merge, the working tree files are updated to reflect the result | |
177 | of the merge. Among the changes made to the common ancestor's version, | |
178 | non-overlapping ones (that is, you changed an area of the file while the | |
179 | other side left that area intact, or vice versa) are incorporated in the | |
180 | final result verbatim. When both sides made changes to the same area, | |
181 | however, git cannot randomly pick one side over the other, and asks you to | |
182 | resolve it by leaving what both sides did to that area. | |
183 | ||
184 | By default, git uses the same style as that is used by "merge" program | |
185 | from the RCS suite to present such a conflicted hunk, like this: | |
186 | ||
187 | ------------ | |
188 | Here are lines that are either unchanged from the common | |
189 | ancestor, or cleanly resolved because only one side changed. | |
190 | <<<<<<< yours:sample.txt | |
191 | Conflict resolution is hard; | |
192 | let's go shopping. | |
193 | ======= | |
194 | Git makes conflict resolution easy. | |
195 | >>>>>>> theirs:sample.txt | |
196 | And here is another line that is cleanly resolved or unmodified. | |
197 | ------------ | |
198 | ||
29b802aa | 199 | The area where a pair of conflicting changes happened is marked with markers |
dcb11263 | 200 | `<<<<<<<`, `=======`, and `>>>>>>>`. The part before the `=======` |
29b802aa | 201 | is typically your side, and the part afterwards is typically their side. |
70a3f897 | 202 | |
29b802aa RW |
203 | The default format does not show what the original said in the conflicting |
204 | area. You cannot tell how many lines are deleted and replaced with | |
205 | Barbie's remark on your side. The only thing you can tell is that your | |
70a3f897 JH |
206 | side wants to say it is hard and you'd prefer to go shopping, while the |
207 | other side wants to claim it is easy. | |
208 | ||
209 | An alternative style can be used by setting the "merge.conflictstyle" | |
210 | configuration variable to "diff3". In "diff3" style, the above conflict | |
211 | may look like this: | |
212 | ||
213 | ------------ | |
214 | Here are lines that are either unchanged from the common | |
215 | ancestor, or cleanly resolved because only one side changed. | |
216 | <<<<<<< yours:sample.txt | |
217 | Conflict resolution is hard; | |
218 | let's go shopping. | |
219 | ||||||| | |
220 | Conflict resolution is hard. | |
221 | ======= | |
222 | Git makes conflict resolution easy. | |
223 | >>>>>>> theirs:sample.txt | |
224 | And here is another line that is cleanly resolved or unmodified. | |
225 | ------------ | |
226 | ||
dcb11263 CJ |
227 | In addition to the `<<<<<<<`, `=======`, and `>>>>>>>` markers, it uses |
228 | another `|||||||` marker that is followed by the original text. You can | |
70a3f897 JH |
229 | tell that the original just stated a fact, and your side simply gave in to |
230 | that statement and gave up, while the other side tried to have a more | |
231 | positive attitude. You can sometimes come up with a better resolution by | |
232 | viewing the original. | |
233 | ||
234 | ||
235 | HOW TO RESOLVE CONFLICTS | |
236 | ------------------------ | |
237 | ||
ffb1a4be JH |
238 | After seeing a conflict, you can do two things: |
239 | ||
29b802aa | 240 | * Decide not to merge. The only clean-ups you need are to reset |
ffb1a4be | 241 | the index file to the `HEAD` commit to reverse 2. and to clean |
35d2fffd JH |
242 | up working tree changes made by 2. and 3.; `git merge --abort` |
243 | can be used for this. | |
ffb1a4be | 244 | |
34ad1afa DH |
245 | * Resolve the conflicts. Git will mark the conflicts in |
246 | the working tree. Edit the files into shape and | |
0b444cdb | 247 | 'git add' them to the index. Use 'git commit' to seal the deal. |
ffb1a4be | 248 | |
34ad1afa DH |
249 | You can work through the conflict with a number of tools: |
250 | ||
ca768288 | 251 | * Use a mergetool. `git mergetool` to launch a graphical |
34ad1afa DH |
252 | mergetool which will work you through the merge. |
253 | ||
ca768288 | 254 | * Look at the diffs. `git diff` will show a three-way diff, |
3588cf94 JN |
255 | highlighting changes from both the `HEAD` and `MERGE_HEAD` |
256 | versions. | |
34ad1afa | 257 | |
3588cf94 JN |
258 | * Look at the diffs from each branch. `git log --merge -p <path>` |
259 | will show diffs first for the `HEAD` version and then the | |
260 | `MERGE_HEAD` version. | |
34ad1afa | 261 | |
ca768288 | 262 | * Look at the originals. `git show :1:filename` shows the |
3588cf94 JN |
263 | common ancestor, `git show :2:filename` shows the `HEAD` |
264 | version, and `git show :3:filename` shows the `MERGE_HEAD` | |
265 | version. | |
ffb1a4be | 266 | |
d504f697 CB |
267 | |
268 | EXAMPLES | |
269 | -------- | |
270 | ||
271 | * Merge branches `fixes` and `enhancements` on top of | |
272 | the current branch, making an octopus merge: | |
273 | + | |
274 | ------------------------------------------------ | |
275 | $ git merge fixes enhancements | |
276 | ------------------------------------------------ | |
277 | ||
278 | * Merge branch `obsolete` into the current branch, using `ours` | |
279 | merge strategy: | |
280 | + | |
281 | ------------------------------------------------ | |
282 | $ git merge -s ours obsolete | |
283 | ------------------------------------------------ | |
284 | ||
285 | * Merge branch `maint` into the current branch, but do not make | |
286 | a new commit automatically: | |
287 | + | |
288 | ------------------------------------------------ | |
289 | $ git merge --no-commit maint | |
290 | ------------------------------------------------ | |
291 | + | |
292 | This can be used when you want to include further changes to the | |
293 | merge, or want to write your own merge commit message. | |
294 | + | |
295 | You should refrain from abusing this option to sneak substantial | |
296 | changes into a merge commit. Small fixups like bumping | |
297 | release/version name would be acceptable. | |
298 | ||
299 | ||
a4081bac JN |
300 | include::merge-strategies.txt[] |
301 | ||
35e9d630 JN |
302 | CONFIGURATION |
303 | ------------- | |
304 | include::merge-config.txt[] | |
305 | ||
306 | branch.<name>.mergeoptions:: | |
307 | Sets default options for merging into branch <name>. The syntax and | |
308 | supported options are the same as those of 'git merge', but option | |
309 | values containing whitespace characters are currently not supported. | |
310 | ||
3c64314c PB |
311 | SEE ALSO |
312 | -------- | |
5162e697 | 313 | linkgit:git-fmt-merge-msg[1], linkgit:git-pull[1], |
483bc4f0 JN |
314 | linkgit:gitattributes[5], |
315 | linkgit:git-reset[1], | |
316 | linkgit:git-diff[1], linkgit:git-ls-files[1], | |
317 | linkgit:git-add[1], linkgit:git-rm[1], | |
318 | linkgit:git-mergetool[1] | |
3c64314c | 319 | |
0f69be53 JH |
320 | GIT |
321 | --- | |
9e1f0a85 | 322 | Part of the linkgit:git[1] suite |