Nonzero status codes take are never received

command.erl

-module(command).
-compile(export_all).

command(Cmd) ->
     Opt = [stream, exit_status, use_stdio,
            stderr_to_stdout, in, eof],
     P = open_port({spawn, Cmd}, Opt),
     get_data(P, []).

get_data(P, D) ->
    receive
        {P, eof} ->
            Status = receive
                       {P, {exit_status, N}} -> N
                     after 3000 -> timeout
                     end,
            port_close(P),
            {Status, lists:flatten(D)};
        {P, {data, D1}} ->
            get_data(P, [D|D1])
    end.