Change old commit messages in Git

Question

I have to replace a text with another one in all the git repo commit messages. It seems to be possible with git rebase -i ... that opens a text editor but I have to do it automatically. Is it doable with some of the git commands or maybe with a Java library?

• Lasse V. Karlsen: I think you can do that with git filter-branch as you essentially get to execute a script per commit, and can change all the metadata in there. Think is the operative word, so I'm leaving this as just a comment.
• mnestorov: If you want to use rebase you can do something like git rebase -i -x "git commit --amend --message yourmessage" refspec. This will allow you to execute arbitrary commands and change any messages.
• ka3ak: @LasseV.Karlsen Yeah. I've used it already. There seems to be a tool that can achieve it by using filter-branch behind the coulisses github.com/da-x/git-search-replace But I've not used it yet.
• torek: Note that in all cases—whether using git rebase or git filter-branch or any other tool—what you're doing is not changing an old commit, but rather, copying that old commit to a new (but different and improved) one. To use the new and improved commit easily, you also then copy any and all subsequent commits.

Answer 1

git filter-branch is the tool to use for automatic bulk history rewriting.

Specifically --msg-filter:

--msg-filter This is the filter for rewriting the commit messages. The argument is evaluated in the shell with the original commit message on standard input; its standard output is used as the new commit message.

In your case, a simple sed as the command might suffice.

Answer 2

git filter-branch is not recommended.

• https://git-scm.com/docs/git-filter-branch#_warning

Use an alternative history filtering tool such as git filter-repo.

• https://github.com/newren/git-filter-repo

git filter-repo --message-callback 'return re.sub(b"#", b"GH-", message)' --force --replace-refs delete-no-add