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This article will discuss using the git rebase command effectively . The git rebase command allows us to change a range of commits and modify the commit history in our repository.

We can edit, reorder, or squash commits using the git rebase command.

Using git rebase from the command line

Here are some common usage options.

1. We can edit previous commit messages.
2. We can merge two or more commits into one.
3. We can revert or delete unnecessary commits in the repository.

When rebasing, we can rebase against a branch or a point in time in the repository.

To rebase against a branch, we run:

$ git rebase --interactive <branch_name>

To rebase to a point in time, we run:

$ git rebase --interacive HEAD~

We can add HEAD~7 to rebase to the seventh commit.

Let's look at the commands available when rebasing.

• pick - We use this to reorder our commit history.
• reword − It is used when we want to change the commit message. It does not affect the changes introduced by the commit.
• edit − It is used when we want to edit or modify a commit. We can split the commit into smaller commits or remove the errors introduced by the commit.
• squash - We use this to merge two commits into one and gives us the opportunity to provide a new message for the new commit.
• fixup - It is the same as squash, except that it discards the merge commit's message and uses the message above it.

We will now try to use the above options in an example. In this example, we will rebase against a point in time in the Delftscopetech repository.

We will rebase HEAD~7 . Run the following command:

$ git rebase --interactive HEAD~7

The text editor displays the following output.

Our commits are sorted from oldest to newest.

In our text editor we will:

1. Use squash to squash commit (fa39187) into commit (1fc6c95).
2. Move the last commit (7b36971) before commit (6b2481b) and keep it as pick.
3. Merge commit (c619268) into commit (6b2481b) with fix-drop commit message.
4. Use Edit Split (dd1475d).
5. Fix the commit message using reword (4ca2acc).

We will modify the command in the text editor as shown below.

We can save and close our text editor, and Git will start the rebase.

Git will skip picking 1fc6c95 and open an editor because squash needs some input from us. It should look something like this.

If you are happy with the changes, you can close the editor and continue with the rebase. The next three commands require no input from us, but the editor does and will print the following messages to the terminal.

At this point, we can make any changes and create a new commit using the git commit --amend command. Once we are done, we can continue by running the git rebase --continue command.

Always run git rebase --continue after making changes. If you forget to run the command and continue coding, you won't be able to rebase later.

However, you can remedy this by:

1. Run git reset --soft HEAD^the command to ref HEAD to the parent.
2. Run git rebase --continueto complete the rebase.

You can also abort the rebase and redo the process by running the git rebase --abort command. This will require you to resolve the merge conflicts again.

The rewrite section will require our input and Git will open the text editor with the following information.

We can change the text, save the file and complete the rebase.

In short, the git rebase command allows us to change the state of a repository based on commits. We can squash, rename, or reorder commits.

Be careful when rebasing and there are merge conflicts.