git fetch upstream
git branch --list -a

git merge upstream/master
git push origin

git rebase -i HEAD~3  # edit last 3 commits

git merge-base master upstream/master   find common ancestor.
git reset <commit>    # Move current branch head to this commit
git reset --hard   # discard all local changes.

# rebase branch xyz with master
git co xyz
git rebase master

# pretty graph output
# git log --graph --all --decorate --oneline
# git log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit --date=relative

# deleting a branch
git branch -D <branch>   # local remove
git push origin --delete <branch>  # remote remove

git fetch -p  # in case you have origin/<branch> locally, but remote is already gone
# this fetches stale stuff as well, thus deleting the origin/<branch>