os_cmd.erl

-spec os_cmd(string()) ->
    {integer(), iolist()}.
os_cmd(Command) ->
    PortOptions = [stream, exit_status, use_stdio, stderr_to_stdout, in, eof],
    PortID = open_port({spawn, Command}, PortOptions),
    os_cmd_collect(PortID, []).

-spec os_cmd_collect(port(), iolist()) ->
    {integer(), iolist()}.
os_cmd_collect(PortID, Data) ->
    receive
        {PortID, {data, D}} ->
            os_cmd_collect(PortID, [D | Data]);
        {PortID, eof} ->
            port_close(PortID),
            receive
                {PortID, {exit_status, ExitCode}} ->
                    {ExitCode, lists:reverse(Data)}
            end
    end.