GitHub多人协作简明教程

本文面向已经了解/熟悉git基本命令但是并不熟悉如何使用GitHub进行多人协作开发项目的同学。

为了简单起见，这里假设只有两个开发人员，HuanianLi 和 DaxiangLi。他们在GitHub上的地址和角色为：

HuanianLi: https://github.com/huanianli # Maintainer
DaxiangLi: https://github.com/daxiangli # Contributor

HuanianLi将创建一个项目kaiba, 然后请DaxiangLi来帮忙做开发。为了真实地进行场景演绎，我们将首先创建两个GitHub帐号。

1. 在GitHub上创建两个帐号（HuanianLi and DaxiangLi，这里以HuanianLi为例)

1.1 打开GitHub的主页： https://github.com/

1.2 点击右上角的Sign up

1.3 跳转到注册页面后，开始Create your personal account，按照要求输入Username, Email Address, Password, 例如：

1.4 点击页面下方的"Create an account"按钮并按照后续提示完成注册。

2. 在Linux桌面上创建两个用户(huanianli and daxiangli)， (这里以huanianli为例)

2.1 创建用户huanianli

root@idorax:~# useradd -d /home/huanianli -m -s /bin/bash -c "Huanian Li" huanianli

2.2 对用户huanianli的git进行设置（这里直接编辑文件~/.gitconfig）

huanianli@ThinkCentre:~$ vim ~/.gitconfig
huanianli@ThinkCentre:~$ cat -n ~/.gitconfig 
     1    [user]
     2        email = huanian.li@gmail.com
     3        name = Huanian Li
     4    [core]
     5        editor = vim
     6    [push]
     7        default = matching
huanianli@ThinkCentre:~$ 
huanianli@ThinkCentre:~$ git config -l
user.email=huanian.li@gmail.com
user.name=Huanian Li
core.editor=vim
push.default=matching
huanianli@ThinkCentre:~$

2.3 在huanianli的HOME目录下创建一个工作空间workspace

huanianli@ThinkCentre:~$ cd ~
huanianli@ThinkCentre:~$ mkdir workspace
huanianli@ThinkCentre:~$ ls
workspace
huanianli@ThinkCentre:~$

3. (Maintainer) HuanianLi在GitHub上创建一个项目kaiba

3.1 登录HuanianLi的GitHub空间，打开页面Repositories, e.g.

https://github.com/HuanianLi?tab=repositories

点击页面右边的New按钮，进入创建一个新的代码仓库的页面。

点击"Create repository"完成创建。

3.2 进入HuanianLi的Linux桌面，clone在3.1创建的项目kaiba

huanianli@ThinkCentre:~$ cd workspace
huanianli@ThinkCentre:~/workspace$ git clone https://github.com/HuanianLi/kaiba.git
Cloning into 'kaiba'...
warning: You appear to have cloned an empty repository.
Checking connectivity... done.
huanianli@ThinkCentre:~/workspace$ ls
kaiba
huanianli@ThinkCentre:~/workspace$ cd kaiba
huanianli@ThinkCentre:~/workspace/kaiba$ vi README.md
huanianli@ThinkCentre:~/workspace/kaiba$ cat -n README.md
     1    kaiba: A sandbox project of Kaiba
huanianli@ThinkCentre:~/workspace/kaiba$
huanianli@ThinkCentre:~/workspace/kaiba$ git add README.md
huanianli@ThinkCentre:~/workspace/kaiba$
huanianli@ThinkCentre:~/workspace/kaiba$ git commit -m "Initialize the project by adding README.md"
[master (root-commit) c0bd2ed] Initialize the project by adding README.md
 1 file changed, 1 insertion(+)
 create mode 100644 README.md
huanianli@ThinkCentre:~/workspace/kaiba$
huanianli@ThinkCentre:~/workspace/kaiba$ git log
commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
huanianli@ThinkCentre:~/workspace/kaiba$
huanianli@ThinkCentre:~/workspace/kaiba$ git branch
* master
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ git push -u origin master
Username for 'https://github.com': HuanianLi
Password for 'https://HuanianLi@github.com':
Counting objects: 3, done.
Writing objects: 100% (3/3), 273 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To https://github.com/HuanianLi/kaiba.git
 * [new branch]      master -> master
Branch master set up to track remote branch master from origin.
huanianli@ThinkCentre:~/workspace/kaiba$

在上面的操作中，关键的步骤是：

clone

git clone https://github.com/HuanianLi/kaiba.git

push

git push -u origin master

注意：因为是第一次push, ‘-u’ 是必须的。

3.3 一旦完成git push之后，我们就可以浏览GitHub上的项目了

4. (Contributor) DaxiangLi登录他的GitHub, 然后进入(Maintainer) HuanianLi的GitHub空间，fork项目kaiba

4.1 DaxiangLi登录他的GitHub

4.2 进入(Maintainer) HuanianLi的GitHub空间, 点开项目kaiba

注意： 目前的 Fork 为0。

4.3 fork项目kaiba, 直接点Fork按钮

Fork 结束后， DaxiangLi的GitHub里就有了项目kaiba

5. （Contributor）DaxiangLi贡献代码给项目kaiba

5.1 DaxiangLi在他的Linux桌面上clone代码

daxiangli@ThinkPad:~/workspace$ git clone https://github.com/DaxiangLi/kaiba.git
Cloning into 'kaiba'...
remote: Counting objects: 3, done.
remote: Total 3 (delta 0), reused 3 (delta 0), pack-reused 0
Unpacking objects: 100% (3/3), done.
Checking connectivity... done.

两个问题：

DaxiangLi 能直接clone HuanianLi的GitHub里的代码吗？ A: 能。
DaxiangLi 能直接clone HuanianLi的GitHub里的代码，然后做修改后push回去吗？ A: 不能。

5.2 DaxiangLi新建一个开发分支

daxiangli@ThinkPad:~/workspace/kaiba$ git checkout -b dev
Switched to a new branch 'dev'

其中， git checkout -b dev 等同于

1 git branch   dev
2 git checkout dev

5.3 把HuanianLi的项目添加到DaxiangLi的远程仓库

daxiangli@ThinkPad:~/workspace/kaiba$ git remote add upstream https://github.com/HuanianLi/kaiba.git

5.4 将HuanianLi的分支取下来并更新到本地

daxiangli@ThinkPad:~/workspace/kaiba$ git remote update
Fetching origin
Fetching upstream
From https://github.com/HuanianLi/kaiba
 * [new branch]      master     -> upstream/master

daxiangli@ThinkPad:~/workspace/kaiba$ git fetch upstream master
From https://github.com/HuanianLi/kaiba
 * branch            master     -> FETCH_HEAD

5.5 合并HuanianLi的分支到本地(注意：这一步在第一次其实不需要)

daxiangli@ThinkPad:~/workspace/kaiba$ git rebase upstream/master
Current branch dev is up to date.

5.6 DaxiangLi添加一个文件并提交commit

daxiangli@ThinkPad:~/workspace/kaiba$ git add foo.py
daxiangli@ThinkPad:~/workspace/kaiba$ git commit -m "DaxiangLi: Add foo.py"
daxiangli@ThinkPad:~/workspace/kaiba$ git push -u origin dev

5.7 进入DaxiangLi的GitHub, 提交一个PR

Q: 什么是PR? （参考资料来源点这里）

A: PR是Pull Request的缩写，是开发者使用GitHub进行协作的利器。简单来说，Pull Request是一种机制，让开发者告诉项目成员一个功能已经完成。一旦feature分支开发完毕，开发者使用GitHub账号提交一个Pull Request。它告诉所有参与者，他们需要审查代码，并将代码并入master分支。Pull Request不只是一个通知，还是一个专注于某个提议功能的讨论版面。Pull Request 需要两个不同的分支或是两个不同的仓库, 其工作原理大概是：

开发者在他们的本地仓库中为某个功能创建一个专门的分支；
开发者将分支推送到公共的GitHub仓库；
开发者用GitHub发起一个Pull Request；
其余的团队成员审查代码，讨论并且做出修改；
项目维护者将这个功能并入官方的仓库，然后关闭这个Pull Request。

现在点击Compare & pull request按钮，就创建一个PR,

点页面下方的Create pull request按钮即可。生成的PR看起来是这样的：

6. (Maintainer) HuanianLi 查看PR并Merge

6.1 HuanianLi查看PR

HuanianLi可能在PR中加入comment, 要求DaxiangLi做相应的修改。这里为简单起见，直接Review通过。

6.2 HuanianLi点Merge pull request

到此为止，DaxiangLi成功地给HuanianLi贡献了一次代码！！当然，这次贡献过程异常简单，因为未涉及到冲突解决。接下来将介绍更复杂的情况，这才是重点:-)

6.3 HuanianLi 查看kaiba并删除无用的commit

6.3.1 使用git pull更新本地空间

huanianli@ThinkCentre:~/workspace/kaiba$ git pull
remote: Counting objects: 4, done.
remote: Compressing objects: 100% (4/4), done.
remote: Total 4 (delta 0), reused 3 (delta 0), pack-reused 0
Unpacking objects: 100% (4/4), done.
From https://github.com/HuanianLi/kaiba
   c0bd2ed..b8a0b63  master     -> origin/master
Updating c0bd2ed..b8a0b63
Fast-forward
 foo.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 foo.py

注意：在顶端的commit不是我们想要的，需要把它移除掉。

commit b8a0b63d8b18f8466e79284ed6022340ca5a43a8
Merge: c0bd2ed 640f6f6
Author: Huanian Li <41667254+HuanianLi@users.noreply.github.com>
Date:   Wed Jul 25 18:55:02 2018 +0800

    Merge pull request #1 from DaxiangLi/dev
    
    DaxiangLi: Add foo.py

6.3.2 使用git rebase -i移除不需要的commit

huanianli@ThinkCentre:~/workspace/kaiba$ git rebase -i c0bd2ed35e10180209726199af422a63a007355f
Successfully rebased and updated refs/heads/master.

在弹出的交互界面中不做任何修改，直接保存退出即可。

6.3.3 使用git push --force强制更新远端的master分支

huanianli@ThinkCentre:~/workspace/kaiba$ git push --force
Username for 'https://github.com': HuanianLi
Password for 'https://HuanianLi@github.com': 
Total 0 (delta 0), reused 0 (delta 0)
To https://github.com/HuanianLi/kaiba.git
 + b8a0b63...640f6f6 master -> master (forced update)

这下清爽啦！！

下面将重点讨论这两种比较复杂的场景：

场景一： PR Review过程中upstream有更新, 但没有冲突需要解决。例如： DaxiangLi继续修改foo.py, 提交一个PR, 在Review的过程中， HuanianLi增加了一个Makefile并提交了代码。
场景二： PR Review过程中upstream有更新, 而且需要解决冲突。例如： DaxiangLi继续修改foo.py, 提交一个PR, 在Review的过程中， HuanianLi也修改了foo.py并提交了代码。

这两种场景是常有的事情，因为PR提交后，在review的过程中可能改动多次。那么，在改动的过程中，别的合作伙伴给upstream里贡献了代码并导致commit增加是常有的事情。而且，别的合作伙伴很可能跟你改动了同一个文件，那么你就需要做冲突解决。

场景一： PR Review过程中upstream有更新, 但没有冲突需要解决

101 - 在开发之前，DaxiangLi先同步upstream，保证remotes/origin/master与remotes/upstream/master一致

daxiangli@ThinkPad:~/workspace$ 
daxiangli@ThinkPad:~/workspace$ git clone https://github.com/DaxiangLi/kaiba.git
Cloning into 'kaiba'...
remote: Counting objects: 6, done.
remote: Compressing objects: 100% (4/4), done.
remote: Total 6 (delta 0), reused 6 (delta 0), pack-reused 0
Unpacking objects: 100% (6/6), done.
Checking connectivity... done.
daxiangli@ThinkPad:~/workspace$ cd kaiba
daxiangli@ThinkPad:~/workspace/kaiba$ ls
README.md
daxiangli@ThinkPad:~/workspace/kaiba$
daxiangli@ThinkPad:~/workspace/kaiba$ git remote add upstream https://github.com/HuanianLi/kaiba.git
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git remote update
Fetching origin
Fetching upstream
From https://github.com/HuanianLi/kaiba
 * [new branch]      master     -> upstream/master
daxiangli@ThinkPad:~/workspace/kaiba$ ls
README.md
daxiangli@ThinkPad:~/workspace/kaiba$
daxiangli@ThinkPad:~/workspace/kaiba$ git fetch upstream master
From https://github.com/HuanianLi/kaiba
 * branch            master     -> FETCH_HEAD
daxiangli@ThinkPad:~/workspace/kaiba$
daxiangli@ThinkPad:~/workspace/kaiba$ git rebase upstream/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to upstream/master.
daxiangli@ThinkPad:~/workspace/kaiba$ ls
foo.py  README.md
daxiangli@ThinkPad:~/workspace/kaiba$
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch -a
* master
  remotes/origin/HEAD -> origin/master
  remotes/origin/dev
  remotes/origin/master
  remotes/upstream/master
daxiangli@ThinkPad:~/workspace/kaiba$
daxiangli@ThinkPad:~/workspace/kaiba$ git push origin master
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Total 0 (delta 0), reused 0 (delta 0)
To https://github.com/DaxiangLi/kaiba.git
   c0bd2ed..640f6f6  master -> master
daxiangli@ThinkPad:~/workspace/kaiba$

102 - DaxiangLi 切换到dev分支

daxiangli@ThinkPad:~/workspace/kaiba$ git branch -a
* master
  remotes/origin/HEAD -> origin/master
  remotes/origin/dev
  remotes/origin/master
  remotes/upstream/master
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git checkout dev
Branch dev set up to track remote branch dev from origin.
Switched to a new branch 'dev'
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch -a
* dev
  master
  remotes/origin/HEAD -> origin/master
  remotes/origin/dev
  remotes/origin/master
  remotes/upstream/master
daxiangli@ThinkPad:~/workspace/kaiba$

103 - DaxiangLi修改foo.py并commit，然后push到remotes/origin/dev

daxiangli@ThinkPad:~/workspace/kaiba$ ls
foo.py  README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ vi foo.py 
daxiangli@ThinkPad:~/workspace/kaiba$ git diff
diff --git a/foo.py b/foo.py
index 55568dd..4ca134c 100644
--- a/foo.py
+++ b/foo.py
@@ -3,6 +3,10 @@
 import sys
 
 def main(argc, argv):
+    if argc != 2:
+        sys.stderr.write("Usage: %s <num>
" % argv[0])
+        return 1
+
     i = 0
     while i < int(argv[1]):
         print "%02d: Hello World." % i
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git status
On branch dev
Your branch is up-to-date with 'origin/dev'.
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

    modified:   foo.py

no changes added to commit (use "git add" and/or "git commit -a")
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git commit -a -m "DaxiangLi: add checking to foo.py"
[dev e1bb21e] DaxiangLi: add checking to foo.py
 1 file changed, 4 insertions(+)
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit e1bb21ee432a56fe83d8b3d79048d1623dde0b4d
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: add checking to foo.py

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git show
commit e1bb21ee432a56fe83d8b3d79048d1623dde0b4d
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: add checking to foo.py

diff --git a/foo.py b/foo.py
index 55568dd..4ca134c 100644
--- a/foo.py
+++ b/foo.py
@@ -3,6 +3,10 @@
 import sys
 
 def main(argc, argv):
+    if argc != 2:
+        sys.stderr.write("Usage: %s <num>
" % argv[0])
+        return 1
+
     i = 0
     while i < int(argv[1]):
         print "%02d: Hello World." % i
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push origin dev
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 388 bytes | 0 bytes/s, done.
Total 3 (delta 1), reused 0 (delta 0)
remote: Resolving deltas: 100% (1/1), completed with 1 local object.
To https://github.com/DaxiangLi/kaiba.git
   640f6f6..e1bb21e  dev -> dev
daxiangli@ThinkPad:~/workspace/kaiba$

现在，从DaxiangLi的GitHub空间里可以看到新增加到dev分支的commit e1bb21e。

104 - DaxiangLi为dev分支的commit e1bb21e创建一个PR

105 - HuanianLi开始review DaxiangLi的PR

105.1 在HuanianLi的GitHub空间里看到的PR

105.2 HuanianLi 给PR#2做review, 要求Daxiang Li做修改，于是Daxiang Li看到的PR是

105.3 - DaxiangLi根据HuanianLi的comments做修改

daxiangli@ThinkPad:~/workspace/kaiba$ vi foo.py
daxiangli@ThinkPad:~/workspace/kaiba$ git diff
diff --git a/foo.py b/foo.py
index 4ca134c..84b0787 100644
--- a/foo.py
+++ b/foo.py
@@ -5,14 +5,14 @@ import sys
 def main(argc, argv):
     if argc != 2:
         sys.stderr.write("Usage: %s <num>
" % argv[0])
-        return 1
+        return (-1)
 
     i = 0
     while i < int(argv[1]):
         print "%02d: Hello World." % i
         i += 1
 
-    return 0
+    return (0)
 
 if __name__ == '__main__':
     argv = sys.argv

daxiangli@ThinkPad:~/workspace/kaiba$
daxiangli@ThinkPad:~/workspace/kaiba$ git add foo.py
daxiangli@ThinkPad:~/workspace/kaiba$ git commit -m "DaxiangLi: add checking to foo.py (2)"
[dev d266d6b] DaxiangLi: add checking to foo.py (2)
 1 file changed, 2 insertions(+), 2 deletions(-)
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit d266d6b3f4b6569e82dcd479c020a53f2d5ef556
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 12:54:48 2018 +0800

    DaxiangLi: add checking to foo.py (2)

commit e1bb21ee432a56fe83d8b3d79048d1623dde0b4d
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: add checking to foo.py

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 331 bytes | 0 bytes/s, done.
Total 3 (delta 1), reused 0 (delta 0)
remote: Resolving deltas: 100% (1/1), completed with 1 local object.
To https://github.com/DaxiangLi/kaiba.git
   e1bb21e..d266d6b  dev -> dev
daxiangli@ThinkPad:~/workspace/kaiba$

105.4 DaxiangLi在PR上做comment, 告诉HuanianLi已经改好了。（注意： PR上出现了两个commit)

commit 1: e1bb21e
commit 2: d266d6b

105.5 HuanianLi 重新检查DaxiangLi的PR

HuanianLi一看DaxiangLi的PR包含了多个commit, 这哪成啊。。。立即给DaxiangLi写comment, 要求合并多个commits为一个commit。

105.6 DaxiangLi着手合并多个commits

daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit d266d6b3f4b6569e82dcd479c020a53f2d5ef556
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 12:54:48 2018 +0800

    DaxiangLi: add checking to foo.py (2)

commit e1bb21ee432a56fe83d8b3d79048d1623dde0b4d
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: add checking to foo.py

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git rebase -i 640f6f6                                                 
[detached HEAD 7bab5c2] DaxiangLi: add checking to foo.py
 Date: Thu Jul 26 11:39:22 2018 +0800
 1 file changed, 5 insertions(+), 1 deletion(-)
Successfully rebased and updated refs/heads/dev.
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 7bab5c2d12389b6a5bf5cd602dff684ea336a52e
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: add checking to foo.py

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ git diff
daxiangli@ThinkPad:~/workspace/kaiba$ git show
commit 7bab5c2d12389b6a5bf5cd602dff684ea336a52e
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: add checking to foo.py

diff --git a/foo.py b/foo.py
index 55568dd..84b0787 100644
--- a/foo.py
+++ b/foo.py
@@ -3,12 +3,16 @@
 import sys
 
 def main(argc, argv):
+    if argc != 2:
+        sys.stderr.write("Usage: %s <num>
" % argv[0])
+        return (-1)
+
     i = 0
     while i < int(argv[1]):
         print "%02d: Hello World." % i
         i += 1
 
-    return 0
+    return (0)
 
 if __name__ == '__main__':
     argv = sys.argv
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push --force
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 404 bytes | 0 bytes/s, done.
Total 3 (delta 1), reused 0 (delta 0)
remote: Resolving deltas: 100% (1/1), completed with 1 local object.
To https://github.com/DaxiangLi/kaiba.git
 + d266d6b...7bab5c2 dev -> dev (forced update)
daxiangli@ThinkPad:~/workspace/kaiba$

注意：

做git push的时候必须使用 'git push --force'
做git rebase -i <commit id>的时候， <commit id>是上一次官方merge的commit id.

关于git rebase -i <commit id>的过程，图解如下：

01 - 开始做rebase

02 - 进入rebase交互界面，注意阅读各个command的含义

03 - 将commit d266d6b应用squash

04 - 在vim里按:wq （保存退出）

05 - 切换到commit交互界面

06 ：删除L6-9, 然后保存退出vim

105.7 DaxiangLi更改一下commit的comment, 重新push

daxiangli@ThinkPad:~/workspace/kaiba$ git commit --amend 
[dev 254347c] DaxiangLi: Add checking to foo.py
 Date: Thu Jul 26 11:39:22 2018 +0800
 1 file changed, 5 insertions(+), 1 deletion(-)
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 254347cbe57fa043ffcc774e26eabdcd63ea8b30
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ git push --force
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 405 bytes | 0 bytes/s, done.
Total 3 (delta 1), reused 0 (delta 0)
remote: Resolving deltas: 100% (1/1), completed with 1 local object.
To https://github.com/DaxiangLi/kaiba.git
 + db73315...254347c dev -> dev (forced update)

105.8 DaxiangLi重新在PR上加comment, 请HuanianLi再次review (注意: PR上现在只有一个commit了)

105.9 HuanianLi 给kaiba.git里添加一个Makefile, 在检查DaxiangLi的PR最近改动之前

huanianli@ThinkCentre:~/workspace/kaiba$ ls
foo.py  README.md
huanianli@ThinkCentre:~/workspace/kaiba$ git log
commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ vi Makefile
huanianli@ThinkCentre:~/workspace/kaiba$ make 
cp foo.py foo && chmod +x foo
huanianli@ThinkCentre:~/workspace/kaiba$ ls
foo  foo.py  Makefile  README.md
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ git add Makefile 
huanianli@ThinkCentre:~/workspace/kaiba$ git commit -m "HuanianLi: Add Makefile"
[master 3609dff] HuanianLi: Add Makefile
 1 file changed, 9 insertions(+)
 create mode 100644 Makefile
huanianli@ThinkCentre:~/workspace/kaiba$ git log
commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
huanianli@ThinkCentre:~/workspace/kaiba$ git branch -a
* master
  remotes/origin/master
huanianli@ThinkCentre:~/workspace/kaiba$ git push 
Username for 'https://github.com': HuanianLi
Password for 'https://HuanianLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 382 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To https://github.com/HuanianLi/kaiba.git
   640f6f6..3609dff  master -> master
huanianli@ThinkCentre:~/workspace/kaiba$

这时候, HuanianLi的master里包含了3个commits, 而DaxiangLi的master里包含了2个commits, dev分支里包含了3个commits。那么，如果DaxiangLi的dev分支里的top commit (254347c) 被合并到HuanianLi的master分支的时候，这一commit可能成为top commit, 也就是第4个commit，当然也可能成为第3个commit。

 1 --- HuanianLi's master branch ---
 2 commit 3609dff HuanianLi: Add Makefile
 3 commit 640f6f6 DaxiangLi: Add foo.py
 4 commit c0bd2ed Initialize the project by adding README.md
 5 
 6 --- DaxiangLi's master branch ---
 7 commit 640f6f6 DaxiangLi: Add foo.py
 8 commit c0bd2ed Initialize the project by adding README.md
 9 
10 --- DaxiangLi's dev    branch ---
11 commit 254347c DaxiangLi: Add checking to foo.py
12 commit 640f6f6 DaxiangLi: Add foo.py
13 commit c0bd2ed Initialize the project by adding README.md
14 
15 #
16 # After commit 7bab5c2 from DaxiangLi's dev    branch
17 # is merged into            HuanianLi's master branch
18 #
19 --- HuanianLi's master branch looks like ---
20 commit 254347c DaxiangLi: Add checking to foo.py
21 commit 3609dff HuanianLi: Add Makefile
22 commit 640f6f6 DaxiangLi: Add foo.py
23 commit c0bd2ed Initialize the project by adding README.md
24 
25 # OR
26 commit 3609dff HuanianLi: Add Makefile
27 commit 254347c DaxiangLi: Add checking to foo.py
28 commit 640f6f6 DaxiangLi: Add foo.py
29 commit c0bd2ed Initialize the project by adding README.md

105.10 HuanianLi再次检查DaxiangLi的PR, 发现只有一个commit了，而且与他的master分支没有冲突，决定merge！！

点击Merge pull request按钮右边的向下箭头，我们可看到有三种Merge方式，这一次，我们将采用Rebase and merge。

105.11 HuanianLi采用Rebase and merge选项处理DaxiangLi的PR

Merge 完毕后，在HuanianLi的GitHub空间可以看到

HuanianLi重新clone一下kaiba.git，通过git检查Merge:

huanianli@ThinkCentre:~/workspace$ git clone https://github.com/HuanianLi/kaiba.git
Cloning into 'kaiba'...
remote: Counting objects: 12, done.
remote: Compressing objects: 100% (9/9), done.
remote: Total 12 (delta 2), reused 9 (delta 1), pack-reused 0
Unpacking objects: 100% (12/12), done.
Checking connectivity... done.
huanianli@ThinkCentre:~/workspace$ cd kaiba
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ git log
commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
huanianli@ThinkCentre:~/workspace/kaiba$

106 - DaxiangLi 需要重新sync一下master (这一过程我们在前面介绍过，按照基本套路执行即可)

daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch 
* dev
  master
daxiangli@ThinkPad:~/workspace/kaiba$ git checkout master
Switched to branch 'master'
Your branch is up-to-date with 'origin/master'.
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch
  dev
* master
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git remote -v
origin    https://github.com/DaxiangLi/kaiba.git (fetch)
origin    https://github.com/DaxiangLi/kaiba.git (push)
upstream    https://github.com/HuanianLi/kaiba.git (fetch)
upstream    https://github.com/HuanianLi/kaiba.git (push)
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git remote update
Fetching origin
Fetching upstream
remote: Counting objects: 6, done.
remote: Compressing objects: 100% (5/5), done.
remote: Total 6 (delta 2), reused 3 (delta 1), pack-reused 0
Unpacking objects: 100% (6/6), done.
From https://github.com/HuanianLi/kaiba
   640f6f6..27aca2b  master     -> upstream/master
daxiangli@ThinkPad:~/workspace/kaiba$

daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git fetch upstream master
From https://github.com/HuanianLi/kaiba
 * branch            master     -> FETCH_HEAD
daxiangli@ThinkPad:~/workspace/kaiba$
daxiangli@ThinkPad:~/workspace/kaiba$ git rebase upstream/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to upstream/master.
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push origin master
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 6, done.
Compressing objects: 100% (6/6), done.
Writing objects: 100% (6/6), 747 bytes | 0 bytes/s, done.
Total 6 (delta 2), reused 0 (delta 0)
remote: Resolving deltas: 100% (2/2), completed with 1 local object.
To https://github.com/DaxiangLi/kaiba.git
   640f6f6..27aca2b  master -> master
daxiangli@ThinkPad:~/workspace/kaiba$

注意： 这里用到的关键命令是：

1 $  git checkout master
2 $[ git remote add upstream https://github.com/HuanianLi/kaiba.git ]
3 $  git remote -v
4 $  git remote update
5 $  git fetch upstream master
6 $  git rebase upstream/master
7 $  git push origin master

107 - DaxiangLi将dev分支也sync一下（跟origin master同步即可），以便下一次做开发

daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch
  dev
* master
daxiangli@ThinkPad:~/workspace/kaiba$ git checkout dev
Switched to branch 'dev'
Your branch is up-to-date with 'origin/dev'.
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch
* dev
  master
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 254347cbe57fa043ffcc774e26eabdcd63ea8b30
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git fetch origin master
From https://github.com/DaxiangLi/kaiba
 * branch            master     -> FETCH_HEAD
daxiangli@ThinkPad:~/workspace/kaiba$ git rebase origin/master
First, rewinding head to replay your work on top of it...
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push origin dev
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
To https://github.com/DaxiangLi/kaiba.git
 ! [rejected]        dev -> dev (non-fast-forward)
error: failed to push some refs to 'https://github.com/DaxiangLi/kaiba.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes (e.g.
hint: 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push origin dev --force
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Total 0 (delta 0), reused 0 (delta 0)
To https://github.com/DaxiangLi/kaiba.git
 + 254347c...27aca2b dev -> dev (forced update)
daxiangli@ThinkPad:~/workspace/kaiba$

注意： 这里用到的关键命令是：

1 $ git checkout dev
2 $ git fetch origin master
3 $ git rebase origin/master
4 $ git push origin dev --force

到这里，场景一我们就介绍完毕了, 接下来介绍场景二。

场景二： PR Review过程中upstream有更新, 而且需要解决冲突

201 - DaxiangLi第一次更改foo.py

daxiangli@ThinkPad:~$ 
daxiangli@ThinkPad:~$ rm -rf workspace/kaiba
daxiangli@ThinkPad:~$ cd workspace
daxiangli@ThinkPad:~/workspace$ 
daxiangli@ThinkPad:~/workspace$ git clone https://github.com/DaxiangLi/kaiba.git
Cloning into 'kaiba'...
remote: Counting objects: 12, done.
remote: Compressing objects: 100% (8/8), done.
remote: Total 12 (delta 2), reused 12 (delta 2), pack-reused 0
Unpacking objects: 100% (12/12), done.
Checking connectivity... done.
daxiangli@ThinkPad:~/workspace$ cd kaiba
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git remote -v
origin    https://github.com/DaxiangLi/kaiba.git (fetch)
origin    https://github.com/DaxiangLi/kaiba.git (push)
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git remote add upstream https://github.com/HuanianLi/kaiba.git
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git remote -v
origin    https://github.com/DaxiangLi/kaiba.git (fetch)
origin    https://github.com/DaxiangLi/kaiba.git (push)
upstream    https://github.com/HuanianLi/kaiba.git (fetch)
upstream    https://github.com/HuanianLi/kaiba.git (push)
daxiangli@ThinkPad:~/workspace/kaiba$

daxiangli@ThinkPad:~/workspace/kaiba$ git branch 
* master
daxiangli@ThinkPad:~/workspace/kaiba$ git branch -a
* master
  remotes/origin/HEAD -> origin/master
  remotes/origin/dev
  remotes/origin/master
daxiangli@ThinkPad:~/workspace/kaiba$ git checkout dev
Branch dev set up to track remote branch dev from origin.
Switched to a new branch 'dev'
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch
* dev
  master
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ vi foo.py
daxiangli@ThinkPad:~/workspace/kaiba$ git diff foo.py
diff --git a/foo.py b/foo.py
index 84b0787..44635b7 100644
--- a/foo.py
+++ b/foo.py
@@ -7,10 +7,8 @@ def main(argc, argv):
         sys.stderr.write("Usage: %s <num>
" % argv[0])
         return (-1)
 
-    i = 0
-    while i < int(argv[1]):
+    for i in range(int(argv[1])):
         print "%02d: Hello World." % i
-        i += 1
 
     return (0)
 
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git add foo.py 
daxiangli@ThinkPad:~/workspace/kaiba$ git commit -m "DaxiangLi: Update foo.py to use for instead of while"
[dev 099cfc7] DaxiangLi: Update foo.py to use for instead of while
 1 file changed, 1 insertion(+), 3 deletions(-)
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 099cfc7de963a4cbe8ceb7088a710bdb4815dd9d
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 16:57:09 2018 +0800

    DaxiangLi: Update foo.py to use for instead of while

commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push origin dev
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 340 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
To https://github.com/DaxiangLi/kaiba.git
   27aca2b..099cfc7  dev -> dev
daxiangli@ThinkPad:~/workspace/kaiba$

202 - DaxiangLi第二次更改foo.py

提交更新到remotes/origin/dev分支后不满意，于是做第二次修改再提交，这里为了保持只有一个commit, 将会用到

$ git commit -a -m "comments" --amend

全部修改过程如下：

daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 099cfc7de963a4cbe8ceb7088a710bdb4815dd9d
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 16:57:09 2018 +0800

    DaxiangLi: Update foo.py to use for instead of while

commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git diff
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ vi foo.py 
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git add foo.py
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git commit -m "DaxiangLi: Update foo.py to use 'for' instead of 'while'" --amend
[dev 3b9d809] DaxiangLi: Update foo.py to use 'for' instead of 'while'
 Date: Thu Jul 26 16:57:09 2018 +0800
 1 file changed, 2 insertions(+), 4 deletions(-)
daxiangli@ThinkPad:~/workspace/kaiba$ git log
commit 3b9d809f249abfd4d5a53d35006d63f341efbacf
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 16:57:09 2018 +0800

    DaxiangLi: Update foo.py to use 'for' instead of 'while'

commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push origin dev --force
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 357 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
To https://github.com/DaxiangLi/kaiba.git
 + 099cfc7...3b9d809 dev -> dev (forced update)
daxiangli@ThinkPad:~/workspace/kaiba$

203 - DaxiangLi创建一个PR

204 - HuanianLi更新foo.py并提交到upstream/master分支

huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ git log
commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ vi foo.py 
huanianli@ThinkCentre:~/workspace/kaiba$ git diff foo.py
diff --git a/foo.py b/foo.py
index 84b0787..a9aa6fe 100644
--- a/foo.py
+++ b/foo.py
@@ -5,14 +5,14 @@ import sys
 def main(argc, argv):
     if argc != 2:
         sys.stderr.write("Usage: %s <num>
" % argv[0])
-        return (-1)
+        return -1
 
     i = 0
     while i < int(argv[1]):
         print "%02d: Hello World." % i
         i += 1
 
-    return (0)
+    return 0
 
 if __name__ == '__main__':
     argv = sys.argv
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ git commit -a -m "HuanianLi: Update foo.py to use return N instead of return (N)"
[master c5221d8] HuanianLi: Update foo.py to use return N instead of return (N)
 1 file changed, 2 insertions(+), 2 deletions(-)
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ git log
commit c5221d81c91d45cda15e33c3bf0e82874d7fcc97
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 17:29:22 2018 +0800

    HuanianLi: Update foo.py to use return N instead of return (N)

commit 27aca2bcc0fcffb26828cac1eebe517439ef49c9
Author: Daxiang Li <bjlhn@126.com>
Date:   Thu Jul 26 11:39:22 2018 +0800

    DaxiangLi: Add checking to foo.py

commit 3609dff98de5a17a09484738328a0e9db1784e0d
Author: Huanian Li <huanian.li@gmail.com>
Date:   Thu Jul 26 13:54:01 2018 +0800

    HuanianLi: Add Makefile

commit 640f6f63f4634915b4e4ed195e9a48d31cabb893
Author: Daxiang Li <bjlhn@126.com>
Date:   Wed Jul 25 18:15:38 2018 +0800

    DaxiangLi: Add foo.py

commit c0bd2ed35e10180209726199af422a63a007355f
Author: Huanian Li <huanian.li@gmail.com>
Date:   Wed Jul 25 16:21:43 2018 +0800

    Initialize the project by adding README.md
huanianli@ThinkCentre:~/workspace/kaiba$ 
huanianli@ThinkCentre:~/workspace/kaiba$ git push origin master
Username for 'https://github.com': HuanianLi
Password for 'https://HuanianLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 325 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
To https://github.com/HuanianLi/kaiba.git
   27aca2b..c5221d8  master -> master
huanianli@ThinkCentre:~/workspace/kaiba$

205 - DaxiangLi再次更新foo.py，故意制造一个冲突

daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git remote update
Fetching origin
Fetching upstream
remote: Counting objects: 3, done.
remote: Compressing objects: 100% (1/1), done.
remote: Total 3 (delta 2), reused 3 (delta 2), pack-reused 0
Unpacking objects: 100% (3/3), done.
From https://github.com/HuanianLi/kaiba
 * [new branch]      master     -> upstream/master
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git branch -a
* dev
  master
  remotes/origin/HEAD -> origin/master
  remotes/origin/dev
  remotes/origin/master
  remotes/upstream/master

daxiangli@ThinkPad:~/workspace/kaiba$ vi foo.py
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git commit -a --amend 
[dev 924729d] DaxiangLi: Update foo.py to use 'for' instead of 'while'
 Date: Thu Jul 26 16:57:09 2018 +0800
 1 file changed, 3 insertions(+), 5 deletions(-)

daxiangli@ThinkPad:~/workspace/kaiba$ git diff remotes/origin/master..
diff --git a/foo.py b/foo.py
index 84b0787..b1070a5 100644
--- a/foo.py
+++ b/foo.py
@@ -5,12 +5,10 @@ import sys
 def main(argc, argv):
     if argc != 2:
         sys.stderr.write("Usage: %s <num>
" % argv[0])
-        return (-1)
+        return (-11)
 
-    i = 0
-    while i < int(argv[1]):
-        print "%02d: Hello World." % i
-        i += 1
+    for i in range(int(argv[1])):
+        print "%02d: Hello World." % (i + 1)
 
     return (0)
 
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git diff remotes/upstream/master..
diff --git a/foo.py b/foo.py
index a9aa6fe..b1070a5 100644
--- a/foo.py
+++ b/foo.py
@@ -5,14 +5,12 @@ import sys
 def main(argc, argv):
     if argc != 2:
         sys.stderr.write("Usage: %s <num>
" % argv[0])
-        return -1
+        return (-11)
 
-    i = 0
-    while i < int(argv[1]):
-        print "%02d: Hello World." % i
-        i += 1
+    for i in range(int(argv[1])):
+        print "%02d: Hello World." % (i + 1)
 
-    return 0
+    return (0)
 
 if __name__ == '__main__':
     argv = sys.argv
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git push --force
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 362 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
To https://github.com/DaxiangLi/kaiba.git
 + 671404d...924729d dev -> dev (forced update)
daxiangli@ThinkPad:~/workspace/kaiba$

制造的冲突是故意将return (-1)改成return (-11)

接下来我们发现，PR上就会显示有冲突了！！

冲突的细节在于foo.py的第8行

好吧，接下来DaxiangLi就需要去解决冲突了！

206 - DaxiangLi解决冲突 (P.S. 解决冲突不是很容易，请仔细看)

206.1 创建一个临时分支dev-scratch （为了演示得更清晰，这里故意删除旧的空间，重新clone一遍，然后从头开始）

daxiangli@ThinkPad:~/workspace/kaiba$ git checkout -b dev-scratch dev
Switched to a new branch 'dev-scratch'

206.2 给临时分支dev-scratch添加upstream的repo

daxiangli@ThinkPad:~/workspace/kaiba$ git remote add upstream https://github.com/HuanianLi/kaiba.git

206.3 让临时分支dev-scratch与upstream/master同步

daxiangli@ThinkPad:~/workspace/kaiba$ git remote update
Fetching origin
Fetching upstream
remote: Counting objects: 3, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 2), reused 2 (delta 1), pack-reused 0
Unpacking objects: 100% (3/3), done.
From https://github.com/HuanianLi/kaiba
 * [new branch]      master     -> upstream/master

daxiangli@ThinkPad:~/workspace/kaiba$ git fetch upstream master
From https://github.com/HuanianLi/kaiba
 * branch            master     -> FETCH_HEAD

daxiangli@ThinkPad:~/workspace/kaiba$ git merge upstream/master
Auto-merging foo.py
CONFLICT (content): Merge conflict in foo.py
Automatic merge failed; fix conflicts and then commit the result.

206.4 在临时分支dev-scratch里合并冲突

daxiangli@ThinkPad:~/workspace/kaiba$ git add foo.py
daxiangli@ThinkPad:~/workspace/kaiba$ git commit -m "DaxiangLi: Merge confilict in foo.py"
[dev-scratch c9af088] DaxiangLi: Merge confilict in foo.py

206.5 将本地的临时分支dev-scratch与本地开发分支dev做比较

daxiangli@ThinkPad:~/workspace/kaiba$ git diff dev..dev-scratch

206.6 切换到本地开发分支dev

daxiangli@ThinkPad:~/workspace/kaiba$ git checkout dev
Switched to branch 'dev'
Your branch is up-to-date with 'origin/dev'.

206.7 将临时分支dev-scratch合并到开发分支dev

daxiangli@ThinkPad:~/workspace/kaiba$ git merge --squash dev-scratch
Updating 924729d..c9af088
Fast-forward
Squash commit -- not updating HEAD
 foo.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

daxiangli@ThinkPad:~/workspace/kaiba$ git commit -a --amend 
[dev 5055a77] DaxiangLi: Update foo.py to use 'for' instead of 'while'
 Date: Thu Jul 26 16:57:09 2018 +0800
 1 file changed, 4 insertions(+), 6 deletions(-)
daxiangli@ThinkPad:~/workspace/kaiba$ 
daxiangli@ThinkPad:~/workspace/kaiba$ git diff dev..dev-scratch
daxiangli@ThinkPad:~/workspace/kaiba$

206.8 把本地的开发dev强制推送到远端的开发dev

daxiangli@ThinkPad:~/workspace/kaiba$ git push origin dev --force
Username for 'https://github.com': DaxiangLi
Password for 'https://DaxiangLi@github.com': 
Counting objects: 3, done.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 373 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
To https://github.com/DaxiangLi/kaiba.git
 + 924729d...5055a77 dev -> dev (forced update)

206.9 删除本地的临时分支dev-scratch

daxiangli@ThinkPad:~/workspace/kaiba$ git branch dev-scratch -D
Deleted branch dev-scratch (was c9af088).

OKAY, 冲突解决完成！重新刷新PR, 发现冲突已经不存在啦。。。

207 - HuanianLi再次检查PR，发现没有冲突，将代码Rebase and merge

208 - DaxiangLi重新sync远端的master分支

使用下面一组命令即可 (其中， [*]为关键命令)

 1 [ ] $ git branch
 2 [*] $ git checkout master
 3 [ ] $ git branch
 4 [ ] $ git log
 5 [*] $ git remote add upstream https://github.com/HuanianLi/kaiba.git
 6 [ ] $ git remote -v
 7 [ ] $ git remote update
 8 [*] $ git fetch  upstream master
 9 [*] $ git rebase upstream/master
10 [ ] $ git log
11 [ ] $ git diff remotes/origin/master..
12 [*] $ git push origin master

209 - DaxiangLi重新sync远端的dev分支 (前面其实已经介绍过)

使用下面的命令即可 (其中， [*]为关键命令)

 1 [*] $ git clone https://github.com/DaxiangLi/kaiba.git
 2 [*] $ git checkout dev
 3 [ ] $ git remote -v
 4 [*] $ git remote add upstream https://github.com/HuanianLi/kaiba.git
 5 [ ] $ git remote -v
 6 [ ] $ git log
 7 [ ] $ git remote update
 8 [*] $ git fetch  upstream master
 9 [*] $ git rebase upstream/master
10 [ ] $ git log --graph
11 [*] $ git push origin dev --force

说明： git remote update可以不做，直接使用git fetch upstream master也okay.

总结：

从upstream fork出代码空间后，总是创建一个dev分支并保存到远端比较好，这样master分支用来与upstream保持同步，dev分支用来做开发
提交PR的时候请在dev分支中总是保存一个用来被合作伙伴review的commit，如不小心提交了多个commit, 需要进行合并，合并的方法是使用git rebase -i
保持PR中只有一个commit的秘诀是使用git commit -a --amend，然后使用git push origin dev --force
养成总是让origin/master与upstream同步的好习惯
不用总是让origin/dev与upstream保持同步，如果PR中显示有冲突就解决冲突，没有就不用管，即使origin/dev与upstream不同步（P.S. git没有recommit功能，所以你无法总是把你的commit放置到top位置）
当一个PR被合并后，不妨也让origin/dev分支与upstream同步，同步的秘诀还是git push origin dev --force
可以认为origin/dev分支是一个沙箱，可以用来随便玩, 玩坏了大不了删除远端的origin/dev分支再重新创建一个；但是请认真对待origin/master
尽可能地使用git rebase upstream/master, 不使用git merge upstream/master, 在做同步的时候
解决冲突请创建一个本地临时分支dev-scratch, 然后将临时分支合并到本地开发分支dev，合并的秘诀是使用 git merge --squash dev-scratch
不需要的临时分支dev-scratch用git branch dev-scratch -D删除，养成不留垃圾分支的好习惯
不小心关掉一个PR可以Re-open, 但是尽量不要在review的过程中删除被review的commit，那样会导致PR被自动关闭

参考资料：