What is the line to add to vimrc for storing .swp files in /tmp on Ubuntu

Question

I feel like I've literally tried everything, but no matter what I add to vimrc, I can't get it to store its annoying .swp files in /tmp. I'm using Ubuntu 16.04. I've obviously looked up this issue extensively, but again, no command I enter seems to work. I always end up with:

E510: Can't make backup file
(add ! to override)

Things I've tried:

set backupdir=$~/tmp//
set directory=$~/tmp//
set backupdir=~/tmp//
set backupdir=$HOME~/tmp//
set backupdir=/tmp//

I mean you name it, I've tried it. So, explicitly, what is the exact code I need to type in vimrc to make it so vim saves it's .swp files in my temporary folder, instead of cluttering my workspace?

Thank you.

Answer 1

Adding the following line to my ~/.vimrc puts .swp files for currently open buffers under /tmp

set directory=/tmp

If you've tried this without issues are you able to verify that vim is reading your vimrc at all?

Answer 2

It appears the issue was I didn't really understand what ~ means. I created a folder called 'tmp' in my home directory, and from there used:

set backupdir=~/tmp//