YJL

1.1   Inserting a commit

This shows how to insert one in the past:

% git checkout -b new-commit after-this-commit-in-master-branch
% # doing stuff for the new commit
% git commit
% git rebase new-commit master

1.2   hg revert

% git reset --hard

2.1   Extracting history

Using filter-branch, see Extracting directory or files with commits history from Git repository.

2.2   Moving a branch to another commit

% git checkout this-branch
% git reset --hard to-this-point