Save file with new filename: append to existing filename

Question

Is there a simple way to (in VIM) do save the currently open file with it\'s current name plus an appended phrase?

IE, from /home/affert/ type vim /

Answer 1

:w %:p_BACKUP

For explanation see How can I expand the full path of the current file to pass to a command in Vim?.

Answer 2

Easy:

 :w %_BACKUP

If you need override:

 :w %_BACKUP!

The it gonna answer:

"filename_BACKUP!" [New] XL, XC written