08 分支管理 —— 多人协作

多人协作

本节内容：

查看远程库信息，使用git remote -v；本地新建的分支如果不推送到远程，对其他人就是不可见的；从本地推送分支，使用git push origin branch-name，如果推送失败，先用git pull抓取远程的新提交；在本地创建和远程分支对应的分支，使用git checkout -b branch-name origin/branch-name，本地和远程分支的名称最好一致；建立本地分支和远程分支的关联，使用git branch --set-upstream branch-name origin/branch-name；从远程抓取分支，使用git pull，如果有冲突，要先处理冲突。

当你从远程仓库克隆时，实际上Git自动把本地的master分支和远程的master分支对应起来了，并且，远程仓库的默认名称是origin。

要查看远程库的信息，用git remote：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git remoteoriginlwenhaodeMacBook-Pro:TestGit lwenhao$

或者用git remote -v显示更详细的信息：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git remote -vorigin	https://github.com/liuwenhaoCN/TestGit.git (fetch)origin	https://github.com/liuwenhaoCN/TestGit.git (push)lwenhaodeMacBook-Pro:TestGit lwenhao$

上面显示了可以抓取和推送的origin的地址。如果没有推送权限，就看不到push的地址。

推送分支

推送分支，就是把该分支上的所有本地提交推送到远程库。推送时，要指定本地分支，这样Git就会把该分支推送到远程库对应的远程分支上：

git push origin master

如果要推送其他分支，比如dev，就改成：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git push origin devTotal 0 (delta 0), reused 0 (delta 0)remote: This repository moved. Please use the new location:remote:   https://github.com/lwenhaoCN/TestGit.gitremote: remote: Create a pull request for 'dev' on GitHub by visiting:remote:      https://github.com/lwenhaoCN/TestGit/pull/new/devremote: To https://github.com/liuwenhaoCN/TestGit.git * [new branch]      dev -> devlwenhaodeMacBook-Pro:TestGit lwenhao$

但是，并不是一定要把本地分支往远程推送，那么，哪些分支需要推送，哪些不需要呢？

• master分支是主分支，因此要时刻与远程同步；
• dev分支是开发分支，团队所有成员都需要在上面工作，所以也需要与远程同步；
• bug分支只用于在本地修复bug，就没必要推到远程了，除非老板要看看你每周到底修复了几个bug；
• feature分支是否推到远程，取决于你是否和你的小伙伴合作在上面开发。

总之，就是在Git中，分支完全可以在本地自己藏着玩，是否推送，视你的心情而定！

抓取分支

多人协作时，大家都会往master和dev分支上推送各自的修改。

现在，模拟一个你的小伙伴，可以在另一台电脑（注意要把SSH Key添加到GitHub）或者同一台电脑的另一个目录下克隆：新建Test文件夹，把TestGit克隆到该文件夹（这个文件夹模拟你的小伙伴）。

lwenhaodeMacBook-Pro:Test lwenhao$ git clone 'https://github.com/lwenhaoCN/TestGit.git'Cloning into 'TestGit'...remote: Enumerating objects: 23, done.remote: Counting objects: 100% (23/23), done.remote: Compressing objects: 100% (10/10), done.remote: Total 23 (delta 3), reused 20 (delta 3), pack-reused 0Unpacking objects: 100% (23/23), done.lwenhaodeMacBook-Pro:Test lwenhao$

当你的小伙伴从远程库clone时，默认情况下，你的小伙伴只能看到本地的master分支。使用git branch命令查看：

lwenhaodeMacBook-Pro:Test lwenhao$ cd TestGit/lwenhaodeMacBook-Pro:TestGit lwenhao$ git branch* masterlwenhaodeMacBook-Pro:TestGit lwenhao$

现在，你的小伙伴要在dev分支上开发，就必须创建远程origin的dev分支到本地，于是他用这个命令创建本地dev分支：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git checkout -b dev origin/devBranch 'dev' set up to track remote branch 'dev' from 'origin'.Switched to a new branch 'dev'lwenhaodeMacBook-Pro:TestGit lwenhao$

并且你的小伙伴修改README.md文件内容：

lwenhaodeMacBook-Pro:TestGit lwenhao$ cat README.md # TestGit创建一个"dev"分支，我来操作。学习分支管理策略。dev、dev、devlwenhaodeMacBook-Pro:TestGit lwenhao$

他就可以在dev上继续修改，然后时不时地把dev分支push到远程：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git add README.md lwenhaodeMacBook-Pro:TestGit lwenhao$ git commit -m "add dev"[dev 0f59233] add dev 1 file changed, 2 insertions(+)lwenhaodeMacBook-Pro:TestGit lwenhao$ git push origin devCounting objects: 3, done.Delta compression using up to 12 threads.Compressing objects: 100% (2/2), done.Writing objects: 100% (3/3), 267 bytes | 267.00 KiB/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/lwenhaoCN/TestGit.git   8faa495..0f59233  dev -> devlwenhaodeMacBook-Pro:TestGit lwenhao$

你的小伙伴已经向origin/dev分支推送了他的提交，而碰巧你也对同样的文件作了修改，并试图推送：

现在返回到你原来的TestGit中，并且修改README.md内容：

lwenhaodeMacBook-Pro:TestGit lwenhao$ cat README.md # TestGit创建一个"dev"分支，我来操作。学习分支管理策略。我自己写的。lwenhaodeMacBook-Pro:TestGit lwenhao$

你自己提交dev分支下的README.md

lwenhaodeMacBook-Pro:TestGit lwenhao$ git add README.md lwenhaodeMacBook-Pro:TestGit lwenhao$ git commit -m "add my"[dev 29bc6cb] add my 1 file changed, 2 insertions(+)lwenhaodeMacBook-Pro:TestGit lwenhao$ git push origin devTo https://github.com/liuwenhaoCN/TestGit.git ! [rejected]        dev -> dev (fetch first)error: failed to push some refs to 'https://github.com/liuwenhaoCN/TestGit.git'hint: Updates were rejected because the remote contains work that you dohint: not have locally. This is usually caused by another repository pushinghint: to the same ref. You may want to first integrate the remote changeshint: (e.g., 'git pull ...') before pushing again.hint: See the 'Note about fast-forwards' in 'git push --help' for details.lwenhaodeMacBook-Pro:TestGit lwenhao$

推送失败，因为你的小伙伴的最新提交和你试图推送的提交有冲突，解决办法也很简单，Git已经提示我们，先用git pull把最新的提交从origin/dev抓下来，然后在本地合并，解决冲突，再推送：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git pullremote: Enumerating objects: 5, done.remote: Counting objects: 100% (5/5), done.remote: Compressing objects: 100% (1/1), done.remote: Total 3 (delta 1), reused 3 (delta 1), pack-reused 0Unpacking objects: 100% (3/3), done.From https://github.com/liuwenhaoCN/TestGit   8faa495..0f59233  dev        -> origin/devThere is no tracking information for the current branch.Please specify which branch you want to merge with.See git-pull(1) for details.    git pull 
     
     
      If you wish to set tracking information for this branch you can do so with:    git branch --set-upstream-to=origin/
      
        devlwenhaodeMacBook-Pro:TestGit lwenhao$
      
     
    

git pull也失败了，原因是没有指定本地dev分支与远程origin/dev分支的链接，根据提示，设置dev和origin/dev的链接：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git branch --set-upstream-to=origin/dev devBranch 'dev' set up to track remote branch 'dev' from 'origin'.lwenhaodeMacBook-Pro:TestGit lwenhao$

在使用git pull：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git pullAuto-merging README.mdCONFLICT (content): Merge conflict in README.mdAutomatic merge failed; fix conflicts and then commit the result.lwenhaodeMacBook-Pro:TestGit lwenhao$

这回git pull成功，但是合并有冲突，需要手动解决，解决的方法和的完全一样。解决后，提交，再push：

lwenhaodeMacBook-Pro:TestGit lwenhao$ git add README.md lwenhaodeMacBook-Pro:TestGit lwenhao$ git commit -m "fix README.md conflict"[dev cd4d07d] fix README.md conflictlwenhaodeMacBook-Pro:TestGit lwenhao$ git push origin devCounting objects: 6, done.Delta compression using up to 12 threads.Compressing objects: 100% (4/4), done.Writing objects: 100% (6/6), 524 bytes | 524.00 KiB/s, done.Total 6 (delta 2), reused 0 (delta 0)remote: Resolving deltas: 100% (2/2), completed with 1 local object.remote: This repository moved. Please use the new location:remote:   https://github.com/lwenhaoCN/TestGit.gitTo https://github.com/liuwenhaoCN/TestGit.git   0f59233..cd4d07d  dev -> devlwenhaodeMacBook-Pro:TestGit lwenhao$

因此，多人协作的工作模式通常是这样：

1. 首先，可以试图用git push origin <branch-name>推送自己的修改；
2. 如果推送失败，则因为远程分支比你的本地更新，需要先用git pull试图合并；
3. 如果合并有冲突，则解决冲突，并在本地提交；
4. 没有冲突或者解决掉冲突后，再用git push origin <branch-name>推送就能成功！

如果git pull提示no tracking information，则说明本地分支和远程分支的链接关系没有创建，用命令git branch --set-upstream-to <branch-name> origin/<branch-name>。