git undo last commit

$ git commit -m "Something terribly misguided"              (1)
$ git reset --soft HEAD~                                    (2)
<< edit files as necessary >>                               (3)
$ git add ...                                               (4)
$ git commit -c ORIG_HEAD                                   (5)

转自： http://stackoverflow.com/questions/927358/how-do-you-undo-the-last-commit