git merge

git merge [-n] [--stat] [--no-commit] [--squash] [--[no-]edit]
	[--no-verify] [-s <strategy>] [-X <strategy-option>] [-S[<keyid>]]
	[--[no-]allow-unrelated-histories]
	[--[no-]rerere-autoupdate] [-m <msg>] [-F <file>] [<commit>…​]
git merge (--continue | --abort | --quit)

	  A---B---C topic
	 /
    D---E---F---G master

git merge topic
 
	  A---B---C topic
	 /         \
    D---E---F---G---H master

# record the result in a new commit along with the names of the two parent commits

git merge --abort

	  A---B---C topic
	 /
    D---E---F---G master

# git merge --abort will abort the merge process and try to reconstruct the pre-merge state

branch master
branch topic 

# the file file.py both in branch master and topic
# where branch topic file.py changed and the other files changed either，
# i just want to keep file.py in branch master,so exec like this

git checktout master
git checkkout -p topic file.py

--ff  
# 快速合并，这个是默认的参数。如果合并过程出现冲突，Git会显示出冲突并等待手动解决

--ff-only  
# 只有能快速合并的情况才合并。如果合并过程出现冲突，Git会自动abort此次merge

--no-ff  
# 不使用快速合并。会生成一次新的提交记录，这个记录只是标识在这里进行了一次merge操作（目前还没想到应用场景）

--squash  
# 压缩合并。将待合并的分支的内容压缩成一个新的提交合并进来

	  A---B---C topic
	 /
    D---E---F---G master
git checkout master

git merge topic --ff 
# master D--E--F--G
          \
           A--B--C

git merge topic --ff-only
# master D--E--F--G
          \
           A--B--C

git merge topic --no-ff
# master D--E--F--G--H(new commit)
          \       /
           A--B--C

git merge squash
# master D--E--F--G--H(the new commit)