git - I need to pop up and trash away a "middle" commit in my master branch. How can I do it?

Question

For example, in the following master branch, I need to trash just the commit af5c7bf16e6f04321f966b4231371b21475bc4da, which is the second due to previous rebase:

commit 60b413512e616997c8b929012cf9ca56bf5c9113
Author: Luca G. Soave <luca.soave@gmail.com>
Date:   Tue Apr 12 23:50:15 2011 +0200

    add generic config/initializers/omniauth.example.rb

commit af5c7bf16e6f04321f966b4231371b21475bc4da
Author: Luca G. Soave <luca.soave@gmail.com>
Date:   Fri Apr 22 00:15:50 2011 +0200

    show github user info if logged

commit e6523efada4d75084e81971c4dc2aec621d45530
Author: Luca G. Soave <luca.soave@gmail.com>
Date:   Fri Apr 22 17:20:48 2011 +0200

    add multiple .container at blueprint layout

commit 414ceffc40ea4ac36ca68e6dd0a9ee97e73dee22
Author: Luca G. Soave <luca.soave@gmail.com>
Date:   Thu Apr 21 19:55:57 2011 +0200

    add %h1 Fantastic Logo + .right for 'Sign in with Github'

I need to mantain

• the First commit 60b413512e616997c8b929012cf9ca56bf5c9113,
• the Third commit e6523efada4d75084e81971c4dc2aec621d45530 and
• the Last commit 414ceffc40ea4ac36ca68e6dd0a9ee97e73dee22

"throwing away" just the Second commit af5c7bf16e6f04321f966b4231371b21475bc4da

How can I do that? Thanks in advance Luca

Answer 1

Rebase or revert are the options. Rebase will actually remove the commit from the history so it will look like that second commit never existed. This will be a problem if you've pushed the master branch out to any other repos. If you try to push after a rebase in this case, git will give you a reject non fast-forward merges error.

Revert is the correct solution when the branch has been shared with other repos. git revert af5c7bf16 will make a new commit that simply reverses the changes that af5c7bf16 introduced. This way the history is not rewritten, you maintain a clear record of the mistake, and other repos will accept the push.

Here's a good way to erase: git rebase -i <commit>^ That takes you to the commit just before the one you want to remove. The interactive editor will show you a list of all the commits back to that point. You can pick, squash, etc. In this case remove the line for the commit you want to erase and save the file. Rebase will finish its work.