How to Install Neovim on Lubuntu 16.04
I'm using Lubuntu 16.04 and we're assuming that we're going to be using gnome-terminal. I couldn't figure out how to get HEX colors in Vim when using Lubuntu's default Terminal application, LXTerminal.
Thus I took some steps to make Gnome terminal the default Terminal application, and added an icon for it in my menu. These steps are described in another section of this document.
Note: If you're looking for info on installing plain Vim, see the end of this post.
Installation
First, we're going to want to install git in order to use vim-plug later: sudo apt install git
Next, I went over to the Ubuntu section of the Neovim installation page
Assuming I needed this dependency, I probably ran: sudo apt-get install software-properties-common
I then chose the unstable version: https://launchpad.net/%7Eneovim-ppa/+archive/ubuntu/unstable
To add the PPA to my system, I ran
sudo add-apt-repository ppa:neovim-ppa/unstable
sudo apt-get update
I then installed Neovim from this PPA by running sudo apt-get install neovim. I think the nvim command worked after that.
Critical changes to Vim config file
First, since on Lubuntu I'm likely only going to use Neovim and not Vim, I renamed my vimrc to init.vim and put it in ~/.config/nvim/ (which I may have had to create myself).
I then changed my vim-plug call to download my plugins to ~/.config/nvim/plugged: call plug#begin('~/.config/nvim/plugged')
I could have chosen to set vim-plug to download plugins to another directory somewhere in ~/.local/, which may have kept the ~/.config directory closer to what I assume is its intended purpose of just being configuration files, and not actual software.
Also, I had to redo this mappings that open my vim config file:
" Quickly open a vertical split of my VIMRC and source my VIMRC
nnoremap <silent> <leader>ev :vs $MYVIMRC<CR>
nnoremap <silent> <leader>sv :so $MYVIMRC<CR>
Syntax Highlighting Colors
I also made sure that set termguicolors was definitely being run in my init.vim file-- on my Mac I ran it only conditionally based on the terminal Vim detected. For now, let's just run it, as gnome-terminal is capable of running hex color vim themes.
System Clipboard
Within Neovim I ran :CheckHealth which kindly informed me that to get system clipboard support, I'd need to install a program called XSel. So back on the terminal I ran sudo apt install xsel and then restarted my terminal.
Then in my init.vim I figured out through trial and error that I needed to use the + register to access the system clipboard, rather than * that I used on MacOS:
" use leader to interact with the system clipboard
nnoremap <Leader>p "+]p
nnoremap <Leader>P "+]P
nnoremap <Leader>y :y+<cr>
nnoremap <Leader>c ^"+c$
nnoremap <Leader>d ^"+d$
vnoremap <Leader>y "+y
vnoremap <Leader>c "+c
vnoremap <Leader>d "+d
Though strangely, custom mappings that use the systemclipboard register still work with the * rather than the +:
" place enter file on system clipboard
nnoremap <Leader>a :%y*<cr>
" In markdown files, Control + a surrounds highlighted text with square
" brackets, then dumps system clipboard contents into parenthesis
autocmd FileType markdown vnoremap <c-a> <Esc>`<i[<Esc>`>la](<Esc>"*]pa)<Esc>
Other Things To Consider
I have Lubuntu installed on an old MacBook, whose track pad sometimes gets triggered when I'm typing. Thus in this Vim configuration I chose to disable my mouse
" disable mouse
autocmd BufEnter * set mouse=
Appendix: Some Notes on Vim (not Neovim)
As of this writing, you can install Vim 7.4.X with something like sudo apt-get vim. To install, Vim 8 currently you need to use a PPA.
But with both versions of Vim I was having trouble getting access to the system clipboard, so I went with Neovim. Though you can have both installed, with their own configurations, pretty easily.