Set your commit email address in Git (source):
$ git config --global "[email protected]"
Undo your most recent commit (source):
$ git commit -m "Something terribly misguided"
$ git reset HEAD~
<< edit files as necessary >>
$ git add ...
$ git commit -c ORIG_HEAD
Move an existing submodule within the same git repository (source):
git mv old/submod new/submod
Resolve a detached head (source):
git branch temp # base new branch on detached head
git checkout master
git merge temp
git branch -d temp
Make an empty commit (good for debugging CI):
git commit --allow-empty -m "Empty commit to trigger post_receive hooks"
Initialize all submodules recursively (source):
git submodule update --init --recursive