neovim/runtime/ftplugin/systemd.vim

" Vim filetype plugin file
" Language:			systemd.unit(5)
" Keyword Lookup Support:	Enno Nagel <enno.nagel+vim@gmail.com>

if !exists('b:did_ftplugin')
  " Looks a lot like dosini files.
  runtime! ftplugin/dosini.vim
endif

if !has('unix')
  finish
endif

if !has('gui_running')
  command! -buffer -nargs=1 Sman silent exe '!' . KeywordLookup_systemd(<q-args>) | redraw!
elseif has('terminal')
  command! -buffer -nargs=1 Sman silent exe 'term ' . KeywordLookup_systemd(<q-args>)
else
  finish
endif

if !exists('*KeywordLookup_systemd')
  function KeywordLookup_systemd(keyword) abort
    let matches = matchlist(getline(search('\v^\s*\[\s*.+\s*\]\s*$', 'nbWz')), '\v^\s*\[\s*(\k+).*\]\s*$')
    if len(matches) > 1
      let section = matches[1]
      return 'LESS= MANPAGER="less --pattern=''(^|,)\s+' . a:keyword . '=$'' --hilite-search" man ' . 'systemd.' . section
    else
      return 'LESS= MANPAGER="less --pattern=''(^|,)\s+' . a:keyword . '=$'' --hilite-search" man ' . 'systemd'
    endif
  endfunction
endif

setlocal iskeyword+=-
setlocal keywordprg=:Sman

if !exists('b:undo_ftplugin') || empty(b:undo_ftplugin)
  let b:undo_ftplugin = 'setlocal keywordprg< iskeyword<'
else
  let b:undo_ftplugin .= '| setlocal keywordprg< iskeyword<'
endif