You can both move and rename files using the same command, mv (move). In this example, use the mv command to rename tempfile to emptyfile:
$ mv tempfile emptyfile $ |
Now list both files again to verify the change:
$ ls *file copyfile emptyfile |
As you can see, tempfile is replaced by emptyfile.
For more information on the mv(1) command, refer to the man Pages(1): User Commands.