VIM

Create the /etc/vim/vimrc.local:

vi /etc/vim/vimrc.local

" This file loads the default vim options at the beginning and prevents
" that they are being loaded again later. All other options that will be set,
" are added, or overwrite the default settings. Add as many options as you
" wish at the end of this file. 

" Load the defaults
" source /usr/share/vim/vim80/defaults.vim

" Prevent the defaults from being loaded again later, if the user doesn't
" have a local vimrc (~/.vimrc)
let skip_defaults_vim = 1
 
" Set more options (overwrites settings from /usr/share/vim/vim80/defaults.vim)
" Add as many options as you wish

" Set the mouse mode to 'r'
if has('mouse')
 set mouse=r
endif

" Toggle paste/nopaste automatically when copy/paste with right click in insert mode:
let &t_SI .= "\<Esc>[?2004h"
let &t_EI .= "\<Esc>[?2004l"

inoremap <special> <expr> <Esc>[200~ XTermPasteBegin()

function! XTermPasteBegin()
 set pastetoggle=<Esc>[201~
 set paste
 return ""
endfunction

Commands:

Add string to the beginning of each line:

:%s/^/string/

Add string to the end of each line:

:%s/$/\string/g