Undo

Looking for the starting files?

The ideal way to follow this walkthrough is to go over the previous topics first. If you want to skip to this topic, you can download the starting files here.

Be aware that you will have to initialize a git repository first via git init in the unzipped folder.

Whoops, we messed up, what now?

Undo changes after staging

Change the text again to “hello devine”, stage these changes via the add command, but don’t commit it yet:

$ echo "hello devine" > hello.txt
$ git add hello.txt
$ git status
On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)

  modified:   hello.txt

You get a hint on how to unstage these changes: via git restore —staged:

git restore --staged hello.txt

The file is still changed, but the changes are not staged anymore.

$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)

  modified:   hello.txt

no changes added to commit (use "git add" and/or "git commit -a")

You can now definitively undo this, by using —just like in the previous topic— git restore:

git restore hello.txt

Undo commits

Let’s say you’ve committed some changes, but for some reason you want to undo them.

echo "hello devine" > hello.txt
git add hello.txt
git commit -m "changed, but not sure about it"

You can do 2 things: either create a new commit that undoes the changes from the previous commit (git revert HEAD), or completely clear the commit from history (git reset --hard _reference-to-commit_).

git revert HEAD

Your terminal will now display a vim or nano editor, into which you can type a commit message. Edit the default message if you want, and type in vim :quit when you’re done. For nano, use Ctrl + X, followed by Yes.

[master 2bc740f] Revert "changed, but not sure about it"
  1 file changed, 1 insertion(+), 1 deletion(-)

The file will now contain the contents from before the last commit.

You can also set a different editor for the merge message edits. Instead of vim, nano is a more user-friendly alternative:

git config --global core.editor "nano"

By the way, you can view a repository’s commit history with the git log command:

$ git log
commit 2bc740f2af93348267c6b3558e1037c5db540600 (HEAD -> master)
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:57:33 2025 +0200

    Revert "changed, but not sure about it"

    This reverts commit 8d977cb2d4855a782e261015645e017c1e128000.

commit 8d977cb2d4855a782e261015645e017c1e128000
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:56:55 2025 +0200

    changed, but not sure about it

commit 5aa411822d8546ef1cd73addc20a022a74deae91
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:54:26 2025 +0200

    changed, but not sure about it

commit 9720321677e0798b540b287398edeaadcb630b17
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:35:21 2025 +0200

    welcome + new world file

commit 7f65053ee86593fb29a3102e03f7ae3f44b112d7
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:32:22 2025 +0200

    changed world to devine

commit 5588c399cd15bc841c89158d72cc4d3938581196
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:30:22 2025 +0200

    first commit

You can see that the “wrong” commit is still in the git history, and the changes were undone via a new commit. Also note that each commit has a unique SHA1 hash ID. You can use these IDs to specify commits on certain commands.

A more drastic way to undo commits is with the git reset command. With git reset you are going to reset your working tree to a particular commit and delete all commits after that commit from the repository.

We want to go back to the state of our commit “welcome + new world file”. Through git log, we find out that the SHA1 ID is 9720321677e0798b540b287398edeaadcb630b17. Specify the SHA1 ID of the commit to where you want to reset after the command. You don’t have to specify the entire ID: the first 4 characters are often sufficient (at least if they are unique):

$ git reset --hard 9720
HEAD is now at 9720321 welcome + new world file

Now when you run git log again, you will see that the commits after 9720 are gone:

$ git log
commit 9720321677e0798b540b287398edeaadcb630b17 (HEAD -> master)
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:35:21 2025 +0200

    welcome + new world file

commit 7f65053ee86593fb29a3102e03f7ae3f44b112d7
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:32:22 2025 +0200

    changed world to devine

commit 5588c399cd15bc841c89158d72cc4d3938581196
Author: Demo user <demo.user@howest.be>
Date:   Wed Sep 1 09:30:22 2025 +0200

    first commit

You will only use such a git reset command to undo local commits. Once you’re collaborating with others, and commits have already been distributed to other users, you use the git revert command to create a new commit that undoes a previous commit.

Resources

https://ohshitgit.com/