http://superuser.com/questions/414110/vim-save-a-file-as-a-different-filename-but-keep-w-as-the-current-filename
:w someOtherFile.c
it will write to that file, but stay editing someFile.c.
vim - save current file with a new name but keep editing current file
原文：http://www.cnblogs.com/cnblogist/p/6125306.html