One of the more powerful features in Git is the command `git rebase

--interactive`, which allows recent commits to be reordered, squashed

together, or even revised completely. The command creates a todo list

and opens it in an editor. The original todo list might look like:

pick deadbee Implement feature XXX

pick c0ffeee The oneline of the next commit

pick 01a01a0 This change is questionable

pick f1a5c00 Fix to feature XXX

pick deadbab The oneline of the commit after

The user can edit the list to make changes to the history, for example

to

pick deadbee Implement feature XXX

squash f1a5c00 Fix to feature XXX

exec make

edit c0ffeee The oneline of the next commit

pick deadbab The oneline of the commit after

This would cause commits `deadbee` and `f1a5c00` to be squashed

together into one commit followed by running `make` to test-compile

the results, delete commit `01a01a0` altogether, and stop after

committing commit `c0ffeee` to allow the user to make changes.

It would be nice to support more flexibility in the todo-list commands

by allowing the commands to take options. Maybe

* Convert a commit into a merge commit:

pick -p c0ffeee -p e1ee712 deadbab The oneline of the commit after

* After squashing two commits, add a "Signed-off-by" line to the

commit log message:

pick deadbee Implement feature XXX

squash --signoff f1a5c00 Fix to feature XXX

or GPG-sign a commit:

pick --gpg-sign=<keyid> deadbee Implement feature XXX

* Reset the author of the commit to the current user or a specified

user:

pick --reset-author deadbee Implement feature XXX

pick --author="A U Thor <author@example.com>" deadbab The oneline of the commit after

The goal of this project would be (1) to add the infrastructure for

handling options on todo-list lines, and (2) implement some concrete

options. A big part of the difficulty of this project is that `git

rebase --interactive` is implemented via a sparsely-commented shell

script. Adding comments and cleaning up the script as you go would be

very welcome.

- Language: sh

- Difficulty: medium

- Possible mentors: Michael Haggerty