Short pulses down to a few femtoseconds to sub-femtosecond regime have opened up vast opportunities for ultrafast dynamics studies. At the LCLS, different modes have been developed in the past years for achieving shorter x-ray pulses, including low-charge mode, slotted-foil scheme etc. We will overview the present short-pulse  operational modes at the LCLS. A recent nonlinear compression mode for sub-femtosecond will also be discussed.