Literate way of moving all files to a new subdirectory

Question

$ mkdir backup && mv * backup/
mv: cannot move `backup' to a subdirectory of itself, `backup/backup'

Works, but issues a warning. Also exit code is 1.

How to do it properly (but not [much] longer)?

Answer 1

bash:

shopt -s extglob
mkdir backup && mv !(backup) backup

Answer 2

Also bash, and sh (afaik):

$ mkdir .backup && mv * .backup/ && mv .backup backup