Question

好。这让我很困惑。我刚刚初始化了一个运行命令git init的空git存储库。然后我将一个文件添加到git的对象库，即git add .我试图创建一个分支，即git branch {branchname}。我收到一个错误，因为根据我所读到的内容，我无法创建一个分支而没有至少提交过一次。好的。我会咬人的。然后我尝试git checkout -b {branchname}。它似乎有效，即我被运送到我刚创建的分支机构。哇？我尝试git checkout master并收到错误error: pathspec 'master' did not match any file(s) known to git.

为什么我能够创建新分支而不是结帐master branch？我忽略了什么或者没有理解？

Answer 1

与master或origin一样，{p> upstream是一项惯例，而非要求。由于您在master中没有提交，因此您也没有任何提交。 HEAD指向尚不存在的引用。当你运行git checkout -b branch时，你会问git：

将HEAD指向的引用复制到。
将您的HEAD指向新参考。

由于您的HEAD指向不存在的引用，因此您不会复制任何内容，最终仍然指向任何内容。只要您继续切换分支而不提交，情况就是这样。

一旦你做了第一次提交，一切都会改变。现在你已经提交了一个提交，你有一个参考，你当前的HEAD指向。下次创建分支时，会有一个重复的引用，因此下次切换时分支不会消失。

实施例（ISH）：

git init
touch test
git add test
# There are no refs at this point, but HEAD is pointing to the nonexistent refs/heads/master
git checkout -b new_branch
git checkout master # fails, no refs (for master)
git checkout -b new_branch2
git checkout new_branch # fails, no refs (for new_branch)
git commit -m "Initial commit." 
# Now you have a ref for new_branch2, but not yet for any other branches.
git checkout -b new_branch3 # new_branch2's ref is duplicated
git checkout new_branch2 # success, you made a commit in this branch so it has a ref
git checkout new_branch3 # success, you made a commit in new_branch2 which this branch's ref is also pointing to.
git checkout master # failure, until you run with '-b' master doesn't have any refs yet.

Answer 2

它最初对我不起作用......

durrantm.../play$ mkdir ggg
durrantm.../play$ cd ggg
durrantm.../ggg$ git init
Initialized empty Git repository in /home/durrantm/play/ggg/.git/
durrantm.../ggg$ git checkout -b newy
fatal: You are on a branch yet to be born

......直到是的，我对master做了初步提交：

durrantm.../ggg$ vi x.x
durrantm.../ggg$ git add .
durrantm.../ggg$ git commit -m"Initial Commit"
[master (root-commit) 75bcf19] Initial Commit
 0 files changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 x.x
durrantm.../ggg$ git checkout -b abc
Switched to a new branch 'abc'
durrantm.../ggg$

为什么git checkout -b {branchname}允许我在尚未提交时创建一个新分支？

2 个答案: