Change last commit

Oh no ! I just committed, providing a wrong message.
No problemo, you can just edit the log of the last commit:

git commit --amend -m "A better description"

Oh no! I forgot that file.

git add file
git commit --amend -m "blah"

Oh no! I forgot that file... but the message's good.

git add file
git commit --amend -C HEAD

Oh no! I forgot to git add ....

vim file
git commit --amend -aC HEAD

Thanks passcod for the update ! ;)