In this article we will learn what is git rebase ? How we can use git rebase ? and how we can undo git rebase using command.

What is git rebase?

git rebase is a command used to reapply commits on top of another base commit. It is used to synchronize a branch with its upstream branch, or to modify the commits in a branch. It can also be used to combine multiple commits into a single commit. It is important to note that rebasing changes the commit history and can cause conflicts if the upstream branch has been updated since the last time the branch was synchronized. It is generally recommended to use git pull --rebase instead of git pull to avoid creating unnecessary merge commits.
 

Use of git rebase

git rebase can be used in several ways there are following possible ways that how we can use git rebase 

1. Synchronizing a branch with its upstream branch: This can be done by running git rebase upstream/branch where "upstream" is the remote and "branch" is the branch you want to synchronize with. Here is the example of Synchronizing a branch with its upstream branch.

git fetch upstream
git rebase upstream/master

This will fetch the latest changes from the "upstream" remote, and then reapplies the commits in the current branch on top of the "master" branch of the "upstream" remote.

2. Modifying commits in a branch: git rebase -i HEAD~n where n is the number of commits from the head you want to modify. This will open a text editor where you can choose to edit, squash, or delete the commits. Here is an example of modifying commits in a branch

git rebase -i HEAD~3

This will open a text editor, where you can edit the last 3 commits, you can choose to edit, squash or delete the commits.
 

3. Combining multiple commits into a single commit: git rebase -i HEAD~n where n is the number of commits you want to combine. This will open a text editor where you can choose to squash the commits into one. Here is the example of combining multiple commits into a single commit

git rebase -i HEAD~5

4. Interactively rebase a branch to another one : git rebase -i otherBranch where otherBranch is the branch you want to rebase to.

5. It's important to note that git rebase can cause conflicts if the upstream branch has been updated since the last time the branch was synchronized. It is generally recommended to use git pull --rebase instead of git pull to avoid creating unnecessary merge commits.
 

How to undo a git rebase?

To undo a git rebase, you can use the command git reflog to find the commit hash of the state before the rebase, and then use git reset command to go back to that state.

following is an example of how to undo a rebase:

git reflog

This command will show a list of all the commits and actions that were made in your repository, find the commit hash of the state before the rebase, and then use

git reset commitSHA

This command will reset your repository to the state of the commit hash you found.

You can also use git rebase --abort to undo a rebase that is currently in progress and has not been completed yet.

It's important to note that undoing a git rebase will discard any changes made during the rebase and restore the repository to its previous state. It's also important to be sure that you have a backup of any important changes that you made before undoing the rebase.