Git：git-pull的用法总结

本篇文章总结一下 git-pull 的用法，主要过程是基于对官网的完整阅读，记录关键笔记和样例，加上自己的理解。整个过程是这样：

git-pull

粗读了一遍 git-pull 的文档，内容很多，恐怕一篇笔记不足以总结到位，可能要分为多篇笔记来总结。

正文

语法

git pull的作用是从一个仓库或者本地的分支拉取并且整合代码。

git pull [<options>] [<repository> [<refspec>…​]]

描述

git pull 相当于 git fetch 跟着一个 git merge FETCH_HEAD 。 <repository> 是仓库的名字， <refspec> 是分支的名字。如果都不写，会有一个默认值。

一个例子：

     A---B---C master on origin
	/
D---E---F---G master
	^
    origin/master in your repository

远程的 master 分支到了 C ，本地的开发到了 G 。

	 A---B---C origin/master
	/         \
D---E---F---G---H master

git pull 之后会生成一个新的 H ，合并两个分支。

如果发生了冲突，可以使用 git reset --merge 进行回退。

options（选项）

下面摘录几个常用的选项。

–allow-unrelated-histories By default, git merge command refuses to merge histories that do not share a common ancestor. This option can be used to override this safety when merging histories of two projects that started their lives independently. As that is a very rare occasion, no configuration variable to enable this by default exists and will not be added.

允许无关的历史，这个选项，更多是在更改远程仓库的时候用到。

–ff When the merge resolves as a fast-forward, only update the branch pointer, without creating a merge commit. This is the default behavior.   –no-ff Create a merge commit even when the merge resolves as a fast-forward. This is the default behaviour when merging an annotated (and possibly signed) tag that is not stored in its natural place in refs/tags/ hierarchy.   –ff-only Refuse to merge and exit with a non-zero status unless the current HEAD is already up to date or the merge can be resolved as a fast-forward.

ff 选项，这几个选项是说合并时是否开启 fast-forward ，快速合并，这个有在另外一篇帖子中详细讲解，这里就不赘述了。

实例

实例：默认使用方式

git pull

按照 git branch 设置的默认跟踪的服务器和分支来拉取。

实例：拉取远程服务器 origin 的 master 分支

git pull origin master