merge相關的操作的命令

git checkout master
git merge alternate
# 解決沖突 .....
git add file_1
git commit -m "Add slternate line 5, 6"
git reset --hard HEAD     # before merge commit將工作目錄和索引還原到git merge命令前狀態
git reset --hard ORIG_HEAD # after merge commit 將工作目錄和索引還原到git merge命令前狀態
git checkout -m            # 把沖突解決方案搞砸了，想要返回到沖突的原始狀態

合并操作：檢出目標分支->確保工作區干凈->執行合并操作。執行合并操作后，另一個分支不受影響。

1. 無沖突合并

合并不涉及相同文件的相同部分

chenyingying01@cyy merge % git checkout master
Switched to branch 'master'
chenyingying01@cyy merge % git status
On branch master
nothing to commit, working tree clean
chenyingying01@cyy merge % git merge alternate
Merge made by the 'recursive' strategy.file | 1 +1 file changed, 1 insertion(+)
chenyingying01@cyy merge % git log --graph --pretty=oneline --abbrev-commit
*   50fc402 (HEAD -> master) Merge branch 'alternate'
|\
| * 4fb8628 (alternate) Add alternate's line 4
* | 608c235 Another file
|/
* 61570a2 Initial 3 line file
chenyingying01@cyy merge %

2. 有沖突合并-手動解決

合并涉及相同文件的相同部分， merge時會產生沖突。需要手動的去修改沖突，然后在add, commmit。 代碼分支合并時必須保證合入后不會影響原有的功能。

chenyingying01@cyy merge % git branchalternate
* master
chenyingying01@cyy merge % cat >> file
Line 5 stuff
Line 6 stuff
chenyingying01@cyy merge % git add file
chenyingying01@cyy merge % git commit -m "Add line 5 and line 6"
[master f0adb70] Add line 5 and line 61 file changed, 2 insertions(+)chenyingying01@cyy merge % git checkout alternate
Switched to branch 'alternate'
chenyingying01@cyy merge % cat >> file
Line 5 alternate stuff
Line 6 alternate stuff
chenyingying01@cyy merge % git diff
diff --git a/file b/file
index 3754bb3..260d21c 100644
--- a/file
+++ b/file
@@ -2,3 +2,5 @@ line 1 stuffline 2 stuffline 3 stuffline 4 alternate stuff
+Line 5 alternate stuff
+Line 6 alternate stuff
chenyingying01@cyy merge % git add file
chenyingying01@cyy merge % git commit -m "Add slternate line 5, 6"
line 1 stuff
[alternate 8de3d40] Add slternate line 5, 61 file changed, 2 insertions(+)chenyingying01@cyy merge % git checkout master
Switched to branch 'master'
chenyingying01@cyy merge % git merge alternate
Auto-merging file
CONFLICT (content): Merge conflict in file
Automatic merge failed; fix conflicts and then commit the result.
chenyingying01@cyy merge % git diff
diff --cc file
index f1209a9,260d21c..0000000
--- a/file
+++ b/file
@@@ -2,5 -2,5 +2,10 @@@ line 1 stufline 2 stuffline 3 stuffline 4 alternate stuff
++<<<<<<< HEAD+Line 5 stuff+Line 6 stuff
++=======
+ Line 5 alternate stuff
+ Line 6 alternate stuff
++>>>>>>> alternate
chenyingying01@cyy merge % vim file              # 手動解決沖突
chenyingying01@cyy merge % git add file
chenyingying01@cyy merge % git commit
[master b80e372] Create commit 7015896: Merge branch "alternate"
chenyingying01@cyy merge % git log --graph --pretty=oneline --abbrev-commit
*   b80e372 (HEAD -> master) Create commit 7015896: Merge branch "alternate"
|\
| * 8de3d40 (alternate) Add slternate line 5, 6
* | f0adb70 Add line 5 and line 6
* | 50fc402 Merge branch 'alternate'
|\|
| * 4fb8628 Add alternate's line 4
* | 608c235 Another file
|/
* 61570a2 Initial 3 line file
chenyingying01@cyy merge %

3. git diff in merge

在編程的過程中，提倡使用幾個單獨概念的，定義良好的提交進行merge，而不是等到最后一個大的龐大提交時再merge.
針對有沖突文件，git diff 命令的輸出是 git diff HEAD 和git diff MERGE_HEAD 命令的結果的組合。

chenyingying01@cyy conflict % git diff
diff --cc hello
index e63164d,562080a..0000000
--- a/hello
+++ b/hello
@@@ -1,3 -1,3 +1,7 @@@hello
++<<<<<<< HEAD+worlds
++=======
+ world
++>>>>>>> altYay!
chenyingying01@cyy conflict % git diff HEAD
diff --git a/hello b/hello
index e63164d..1f2f61c 100644
--- a/hello
+++ b/hello
@@ -1,3 +1,7 @@hello
+<<<<<<< HEADworlds
+=======
+world
+>>>>>>> altYay!
chenyingying01@cyy conflict % git diff MERGE_HEAD
diff --git a/hello b/hello
index 562080a..1f2f61c 100644
--- a/hello
+++ b/hello
@@ -1,3 +1,7 @@hello
+<<<<<<< HEAD
+worlds
+=======world
+>>>>>>> altYay!

4. 廢棄合并

# 1.before merge commit 將工作目錄和索引還原到git merge命令前狀態
git reset --hard HEAD
# 2.after merge commit 將工作目錄和索引還原到git merge命令前狀態
# ORIG_HEAD git 把原始分支的HEAD放在ORIG_HEAD中
git reset --hard ORIG_HEAD  
# 3.把沖突解決方案搞砸了，想要返回到沖突的原始狀態
git checkout -m

5. 合并策略

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