Rebase
The act of changing the base commit.
Example
Let's return to our example from Merge chapter.
There were master, feature1 and feature2 branches originally, then feature1 got modified and then merged to master, making the whole situation look like this::
o "New feature 1" [master] [feature1]
|
o "Initial commit" [feature2]
Imagine we now add some new functionality to feature2:
o "New feature 1" [master] [feature1]
|
| o "New feature 2" [feature2]
|/
o "Initial commit"
You can see the feature2 branch is no longer at the "Initial commit", but it created a true separate branch in the commit tree.
So far so good, but you might notice the feature2 no longer contains the changes from the updated master, which is now on the New feature 1 commit.
How to make feature2 contain the current master code + the changes in New feature 2 commit?
The answer is, to rebase the feature2 on the current master. That is the same as rebasing feature2 on the New feature1 commit, by the way.
After the rebase on master, the commit tree looks like this:
o "New feature 2" [feature2]
|
o "New feature 1" [master] [feature1]
|
o "Initial commit"
Looking at the commit tree, we can see it is linear sequence again, with "Initial commit" being first, "New feature 1" second and "New feature 2" the last commit.
The code at the "New feature 2" contains the cumulative contents of the two previous commits, and it is ready to be merged to master.
If we would try to merge
feature2without rebase, we would revert changes inmaster!