多人协作

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

$ git remote
origin

或者,用git remote -v显示更详细的信息:

$ git remote -v
origin  [email protected]:michaelliao/learngit.git (fetch)
origin  [email protected]:michaelliao/learngit.git (push)

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:

$ git push origin dev

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!

http://michaelliao.gitcafe.io/video/git-push-origin.mp4

抓取分支

多人协作时,大家都会往masterdev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:

$ git clone [email protected]:michaelliao/learngit.git
Cloning into 'learngit'...
remote: Counting objects: 46, done.
remote: Compressing objects: 100% (26/26), done.
remote: Total 46 (delta 16), reused 45 (delta 15)
Receiving objects: 100% (46/46), 15.69 KiB | 6 KiB/s, done.
Resolving deltas: 100% (16/16), done.

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。不信可以用git branch命令看看:

$ git branch
* master

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

$ git checkout -b dev origin/dev

现在,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:

$ git commit -m "add /usr/bin/env"
[dev 291bea8] add /usr/bin/env
 1 file changed, 1 insertion(+)
$ git push origin dev
Counting objects: 5, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 349 bytes, done.
Total 3 (delta 0), reused 0 (delta 0)
To [email protected]:michaelliao/learngit.git
   fc38031..291bea8  dev -> dev

http://michaelliao.gitcafe.io/video/git-push-by-xiaohuoban.mp4

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:

$ git add hello.py
$ git commit -m "add coding: utf-8"
[dev bd6ae48] add coding: utf-8
 1 file changed, 1 insertion(+)
$ git push origin dev
To [email protected]:michaelliao/learngit.git
 ! [rejected]        dev -> dev (non-fast-forward)
error: failed to push some refs to '[email protected]:michaelliao/learngit.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Merge the remote changes (e.g. 'git pull')
hint: before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

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:

$ git pull
remote: Counting objects: 5, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 3 (delta 0)
Unpacking objects: 100% (3/3), done.
From github.com:michaelliao/learngit
   fc38031..291bea8  dev        -> origin/dev
There 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 <remote> <branch>

If you wish to set tracking information for this branch you can do so with:

    git branch --set-upstream dev origin/<branch>

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devorigin/dev的链接:

$ git branch --set-upstream dev origin/dev
Branch dev set up to track remote branch dev from origin.

再pull:

$ git pull
Auto-merging hello.py
CONFLICT (content): Merge conflict in hello.py
Automatic merge failed; fix conflicts and then commit the result.

这回git pull成功,但是合并有冲突,需要手动解决,解决的方法和分支管理中的解决冲突完全一样。解决后,提交,再push:

$ git commit -m "merge & fix hello.py"
[dev adca45d] merge & fix hello.py
$ git push origin dev
Counting objects: 10, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (5/5), done.
Writing objects: 100% (6/6), 747 bytes, done.
Total 6 (delta 0), reused 0 (delta 0)
To [email protected]:michaelliao/learngit.git
   291bea8..adca45d  dev -> dev

http://michaelliao.gitcafe.io/video/git-pull-push-fix.mp4

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 branch-name origin/branch-name

这就是多人协作的工作模式,一旦熟悉了,就非常简单。

小结

  • 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。