-- start applications only once
function run_once(prg, args)
    if not prg then
        do return nil end
    end
    if not args then
        args = ""
    end

    awful.util.spawn_with_shell('pgrep '..prg..' || ('..prg..' '..args..')')
end

-- start application only once (with path to detect original app started by a script with the same name)
function run_once_p(path, prg, args)
    if not prg or not path then
        do return nil end
    end
    if not args then
        args = ""
    end

    awful.util.spawn_with_shell('pgrep '..prg..' || ('..path..prg..' '..args..')')
end

-- start applications via starter which differs from applicationname when running
function run_once_spec(prg, prgs, args)
  if not prg or not prgs then
    do return nil end
  end
  if not args then
    args=""
  end

  awful.util.spawn_with_shell('pgrep '..prgs..' || ('..prg..' '..args..')')
end