How to delete previous versions in git

Git is one of the most popular version control tools today. Its power and flexibility are preferred by developers and teams, and Git can track all changes and history of a project. However, as development progresses, some older versions may need to be removed. This article will tell you how to delete old versions and clean up your Git history.

1. Git Reset

You can easily delete old versions using the Git Reset command, which will point the HEAD (current branch) to the old version you want to delete. Note that since Git Reset actually points HEAD to the old version, it loses all changes made after that version.

The command to point HEAD to the old version is as follows:

git reset <commit>

where bc59094fbd619487e70ee0dbb7ee2c82 is the old version number you want to delete. For example, if you want to delete the two latest commits, the command is as follows:

git reset HEAD~2

This will point HEAD to the third to last commit.

The simple command will reset HEAD but will not delete the commit. If you really want to delete the commit, you need to use the "--hard" option:

git reset --hard <commit>

Remember, this is a no-return operation. If you have switched to this commit and need to restore, please create a backup.

2. Git Revert

Using Git Revert creates a new commit that undoes the changes made to the older version. This is a safer approach as it does not delete the commit but creates a new commit to undo the changes in the old version.

The command to undo a commit is as follows:

git revert <commit>

where bc59094fbd619487e70ee0dbb7ee2c82 is the old version number you want to undo. For example, to undo the two most recent commits, type the following:

git revert HEAD~2..HEAD

This creates a new commit that undoes all changes from the third to last commit to the latest commit.

3. Git Rebase

The above two methods are one way to change the history. If you use Git Reset or Git Revert in a shared branch, you may cause history errors for others. This is where Git Rebasing comes in.

Git Rebase is a method of organizing commits to form a new history. By integrating commits from one branch into commits from another branch, you clean up your branch history and remove old versions.

The command is as follows:

git rebase -i <commit>

where the -i flag turns on an interactive reflow where you can select commits to delete. For example, to remove the two most recent commits, type:

git rebase -i HEAD~2

Then change the list of commits in the editor to:

pick abcdefg commit message
d eeeeee commit message
d fffffff commit message

Set the first two items to "Pick" and the others Both items are set to "d" (delete). Save and close the editor, and Git will recreate a new history record.

Summary

The above are three ways to delete old versions using Git. Each method is suitable for different scenarios and has its own advantages and disadvantages. Please choose the method that works best for you based on your specific situation. Whichever way you choose, always remember to make a backup before deleting a commit so you can restore your code if you need to restore it.

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