Prevent Vim from clearing the clipboard on exit

Synthesizing answers from superuser, just add the following to your .vimrc

autocmd VimLeave * call system("xsel -ib", getreg('+'))

Install Parcellite, or glipper for Gnome and klipper for KDE.

Restart your computer or run it manually.

see: https://wiki.ubuntu.com/ClipboardPersistence