Let’s say you made a few commits and then realized that you did them to the wrong branch. Because git is awesome, it’s really easy to change the branch you committed to.
Let’s learn why!
Every commit stores the SHA-1 hash of its parent commit(s). Think of it as a directed acyclic graph with each node pointing to its parent(s).
A branch is just a pointer to a commit. Git only stores a single file with the filename being the name of the branch. Inside, there is only the SHA-1 of the top-most commit.
Or to quote the great book Git Internals:
Creating a branch is nothing more than just writing 40 characters to a file.
Go for it and have a look in the
.git directory of some git repository.
.git/refs/heads stores the branch reference files.
Let’s say you are on the master branch and create another branch named
The new branch
dev is pointing to the same commit as master. If we draw that, it would look like this:
With the knowledge of commits and branches you can probably come up with a solution yourself.
At this point you noticed that you want commits
E on a new branch called
To “remove” the commits from the master branch, you simply move the branch pointer two commits back. Please note the two carets (
Because commits are just referencing their parents,
E are now unreachable from
master. Now you can just switch to your new branch and keep working on it.
I hope you agree with me that this is really easy once you understood what these commands do internally. For further reading, I highly recommend reading the Think-like-a-git website and the mentioned Git Internals book by Peepcode.