同步一个 fork

平时都是用 Hg（Mercurial），Git 用得不是很熟练，老是遗忘，特此记录一下。
其实都是根据 GitHub 官方 help 整理的（Syncing a fork、Configuring a remote for a fork）。

配置 remote

1. 使用git remote -v查看远程状态

   $ git remote -v
   origin  https://github.com/YOUR_USERNAME/YOUR_FORK.git (fetch)
   origin  https://github.com/YOUR_USERNAME/YOUR_FORK.git (push)

2. 添加一个上游仓库

   git remote add upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git

3. 再次确认

   $ git remote -v
   origin    https://github.com/YOUR_USERNAME/YOUR_FORK.git (fetch)
   origin    https://github.com/YOUR_USERNAME/YOUR_FORK.git (push)
   upstream  https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git (fetch)
   upstream  https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git (push)

同步

1. 从上游仓库 fetch 分支和提交点，传送到本地，并会被存储在一个本地分支 upstream/master

   $ git fetch upstream
   remote: Counting objects: 75, done.
   remote: Compressing objects: 100% (53/53), done.
   remote: Total 62 (delta 27), reused 44 (delta 9)
   Unpacking objects: 100% (62/62), done.
   From https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY
   \* [new branch]      master     -> upstream/master

2. 切换到本地主分支（如果不在的话）

   $ git checkout master
   Switched to branch 'master'

3. 把 upstream/master 分支合并到本地 master 上，这样就完成了同步，并且不会丢掉本地修改的内容。

   $ git merge upstream/master
   Updating a422352..5fdff0f
   Fast-forward
   README                    |    9 -------
   README.md                 |    7 ++++++
   2 files changed, 7 insertions(+), 9 deletions(-)
   delete mode 100644 README
   create mode 100644 README.md

4. 最后直接git push origin master，大功告成。