Awesome (window manager) configuration opening terminal in focused client working directory

rc.lua

awful.key({ modkey, }, "Return",
  function ()
    pid = client.focus.pid
    cpid = string.gsub(awful.util.pread('pgrep -P ' .. pid), "[\r\n]+$", "")
    cwd = string.gsub(awful.util.pread('readlink /proc/' .. cpid .. '/cwd'), "[\r\n]+$", "")
    if string.len(cwd) > 0 then
      awful.util.spawn(terminal .. ' -cd ' .. cwd)
    else
      awful.util.spawn(terminal)
    end
  end)